1Please see the [Release Notes for 3.3](https://github.com/mikebrady/shairport-sync/releases/tag/3.3). 2 3Version 3.3.8 4==== 5**Enhancements** 6* Documentation for the MQTT interface. Many thanks to [minix1234](https://github.com/minix1234)! 7 8**Bug Fixes** 9* Fix a bug in the `alsa` back end. In the interval between checking that the alsa device handle was non-`NULL` and actually using it, the handle could be set to `NULL`. The interval between check and usage is now protected. 10* Fix a bug in the `alsa` precision timing code. Thanks to [durwin99](https://github.com/durwin99), [Nicolas Da Mutten](https://github.com/cleverer), [mistakenideas](https://github.com/mistakenideas), [Ben Willmore](https://github.com/ben-willmore) and [giggywithit](https://github.com/giggywithit) for the [report](https://github.com/mikebrady/shairport-sync/issues/1158). 11* Fix a bug that caused Shairport Sync to hang, but not actually crash, if an `on-...` script failed. 12* Fix a crash that occurred if metadata support is enabled during compilation but turned off in the configuration file. Thanks to [Tim Curtis](https://github.com/moodeaudio) for the report. 13* Fix a crash that occurred playing from AirPower on Android. Thanks to [Ircama](https://github.com/Ircama) for the report. 14* Fix the configure.ac file so that `--without-<feature>` configuration options are not interpreted as `--with-<feature>` options instead! Thanks to [David Racine](https://github.com/bassdr) for the report. 15 16Version 3.3.7 17==== 18**Docker Integration** 19* Docker Hub integration. From now on, prebuilt Docker images should be available on the Docker Hub at https://hub.docker.com/r/mikebrady/shairport-sync. 20 21**New Feature** 22* For the PulseAudio backend `pa`, added a new `server` entry to the `pa` section of the configuration file, allowing you to specify a connection to a remote or a local system PulseAudio instance instead of letting PulseAudio choose. Thanks to [Guillaume Revaillot](https://github.com/grevaillot) for this new feature. 23 24**Pesky Changes** 25* The underlying timing system has been moved from 64-bit fixed-point time representation (like NTP) to a 64-bit unsigned nanoseconds representation. This should make precisely no difference to the functionality of Shairport Sync but the transition might inadvertently have introduced bugs. Problem reports gratefully received. 26 27**Bug Fixes** 28* Fixed a number of bugs that prevented Shairport Sync from terminating cleanly in response to the `MPRIS` interface's `Quit()` command. Thanks to [João Gabriel](https://github.com/jgabriel98) for reporting this issue. 29* Related to the above, the code used to terminate the application after a fatal error has been cleaned up. It now uses the correct `exit()` call rather than the rather hacky `abort()` call, returning the value of the constant `EXIT_FAILURE` (typically `1`) to the caller . 30* Fixed a bug whereby the start and end of active mode tokens `abeg` and `aend` where not generated or published -- `pend` tokens were being generated instead. Thanks to [minix1234](https://github.com/minix1234) for the bug report and [fix](https://github.com/mikebrady/shairport-sync/pull/1023). 31* Fixed a bug calculating the instantaneous synchronisation error. This bug could occasionally cause Shairport Sync to lose synchronisation and maybe even to mute for a few seconds before resynchronising. It was caused doing modulo arithmetic incorrectly and it's been there for a while. 32* Removed a bug which would affect initial synchronisation if a `FLUSH` command was received from the player at an inopportune time. 33* Added code to do calculations involving the `audio_backend_latency_offset_in_seconds` and `audio_backend_silent_lead_in_time` settings correctly. Many thanks to [Tucker Kern](https://github.com/mill1000) for discovering a number of bugs associated with this and for [proposing a solution](https://github.com/mikebrady/shairport-sync/pull/1001). This prompted a closer investigation and a number of further improvements were made, and a few "hostages to fortune" removed. 34* The DACP ID looks like a 64-bit number expressed in hexadecimal. It is normally quoted with leading zeroes removed, but in the `_dacp._tcp` service string, leading zeros are not removed from the DACP ID. The bug fix removes those leading zeroes. Thanks to [julianc1969](https://github.com/juliandc1969) for tracking down this bug so tenaciously! 35* Make the first output backend in the list of backends the default and make its name the default `output_name`. 36* Fix a flaw in resyncing -- a flush is set up but not triggered. 37* Ensure metadata and cover art are enabled if metadata support is included at compilation. 38* Set convolution defaults even if no configuration file is found. 39* Handle the `active_remote_id` token as a string rather than an unsigned 32-bit number -- it seems ROON uses a longer character sequence. 40 41**Enhancements** 42* Added the strings `-alac` and `-jack` to the the version string returned by the `-V` command line option if Apple ALAC decoder support and Jack Audio support are included respectively. 43* Cleaned up and simplified the code that handles `FLUSH` requests coming from the player. (Debug messages are still a little verbose.) 44* Improved timing estimation. Shairport Sync has been using linear least-squares regression to estimate timing drift between the (remote) source clock and the local clock. This technique is now extended to provide an estimate of the remote-to-local clock difference itself. (The remote-to-local clock difference is used to remap the timing of audio frames from the remote device's clock to the local clock.) 45 46 Timing drift estimates are now saved when a sessions ends, keyed to the client IP number. When a new session starts from that IP number, the stored estimate is used until a new estimate can be generated from the new session. 47 48 In practice, the timing techniques in use up to now have been very accurate, but this should result in slightly smoother rates of correction. 49* Tidied up the creation and initial opening of pipes. Suppress repeated pipe-opening error messages. 50* Tidied up warnings and fatal error messages when log verbosity is zero. 51* Cleaned up the code that provides a silent lead-in to play on a back end without synchronisation, e.g. a pipe or `stdout`. 52* Added in commented-out code to check the timeliness of the release of audio to a back end without synchronisation, e.g. a pipe or `stdout`. TL;DR – so long as the back end does not block, frames will be released to it not more than one packet (352 frames) late. 53* Logs and statistics can now be directed to the system log (default), `stdout`, `stderr` or to a file or pipe of your choice using a new setting, `log_output_to` in the `diagnostics` section of the configuration file. This is very useful when the system log is disabled or diverted. 54* Audio data from the `pipe` back end and metadata from the metadata pipe are now written using standard blocking `write` commands rather than a slightly complex non-blocking write function. Pipes are now opened in non-blocking mode and changed to blocking mode when successfully opened. 55* Add a default name for the pipe backend: `/tmp/shairport-sync-audio`. 56* Separate threads are now used for each metadata subsystem. Until now, all metadata was processed on a single thread. This included writing to the metadata pipe and the multicast stream and supplying metadata for the `mqtt` interface and for the `dbus` and `MPRIS` interfaces. Unfortunately, that meant that a problem with any one of these subsystems could propagate into the others. Now they all run on separate threads. If one thread blocks, it will not interfere with the other subsystems. 57* Cleaned up and improved the code to synchronise the first frame of audio. This should result in more accurate and reliable initial synchronisation, usually to under a millisecond, and often to within 20 or 30 microseconds. Syncronisation should improve even when the silent lead-in time is as short as 0.3 seconds or when the `audio_backend_latency_offset_in_seconds` is as much as -1.7 seconds, i.e. when only 0.3 seconds of latency are left when the latency would normally be 2.0 seconds. 58* Cleaned up some confused uses of modulo arithmetic. 59* Cleaned up the allocation of memory for gathering running statistics – the heap is now used instead of the stack. 60* Cleaned up the display of statistics for backends that do not implement active synchronisation, e.g. the `pipe` and `STDOUT` back ends. 61* Cleaned up the `audio_backend_silent_lead_in_time` setting by adding an `"auto"` setting. 62* Improved synchronisation accuracy with short silence lead-ins. 63* While a player is active, the DACP port number to which to send remote commands should be broadcast over ZEROCONF/Bonjour. However, if that information is not available, Shairport Sync will now check for it every two seconds. 64* The timing software in the `sndio` backend does some extra sanity checking on certain time estimates, it may help a little when running on virtual machines. 65* Open metadata and audio pipes with 666 permissions to allow them to be shared by other applications. 66 67Version 3.3.6 68==== 69**New Features** 70* Resampling has been added for the [Jack Audio](http://jackaudio.org) backend. This can be used to up-sample to 192kHz. Thanks to [Pieter De Gendt](https://github.com/pdgendt) for this addition. 71 72**Enhancements** 73* Add `SetAirplayVolume` to the native D-Bus `RemoteControl` interface. 74* Add `SetVolume` to the `MPRIS` interface. 75* Add a few sample commands, including `MPRIS` commands, to the [Sample D-Bus Commands](https://github.com/mikebrady/shairport-sync/blob/master/documents/sample%20dbus%20commands) document. 76 77 78**Bug Fixes** 79* Add a `SIGCHLD` handler to remove completed processes that were used to perform program "hooks" without waiting for completion and thus prevent them from becoming zombie processes. Thanks to [patrickjane](https://github.com/patrickjane) for reporting the bug and for suggesting a solution. Addresses issue [#968](https://github.com/mikebrady/shairport-sync/issues/968). 80* Fix a bug in the provision of metadata which would on occasion cause metadata from the previous track to be provided. Thanks to [Tuomas Hämäläinen](https://github.com/tuomashamalainen) and [HiFiBerry](https://github.com/hifiberry) for reporting. This bugfix addresses issue [#972](https://github.com/mikebrady/shairport-sync/issues/972). 81* Make Shairport Sync compile in the forthcoming Fedora 32. Fedora 32 uses GCC-10 which [defaults to `-fno-common`](https://gcc.gnu.org/gcc-10/porting_to.html) exposing a number of issues with Shairport Sync – multiple definitions of some `enum`s and failure to define certain variables as `extern`. Many thanks to [Bill Peck](https://github.com/p3ck) for bringing this issue to notice. Address issue [#973](https://github.com/mikebrady/shairport-sync/issues/973). 82* Treat the `mper` (Persistent ID of a track) metadata attribute as the 64-bit item that it really is rather than a 32-bit item as hithereto. Output it as a hexadecimal number on the MPRIS and D-Bus interfaces to correspond with the format of the persistent id obtained from AppleScript. Thanks to to Scott Simon (https://github.com/zutroy97) for finding a related bug in the [shairport-sync-metadata-reader](https://github.com/mikebrady/shairport-sync-metadata-reader). 83* Hook up the `Volume` property in the `MPRIS` interface. 84* Fix an incompatibilty with Forked Daapd that was causing Forked Daapd to lock up. Thanks to [@tomgadow](https://github.com/tomgadow) and [@ejurgensen](https://github.com/ejurgensen) for their help in finding and (hopefully) fixing this issue. Addresses issue [#953](https://github.com/mikebrady/shairport-sync/issues/953) and [Forked Daapd Issue #870](https://github.com/ejurgensen/forked-daapd/issues/870). 85* Other minor bug fixes. 86 87**Pesky Changes You Might Not Be Able To Ignore** 88* Renamed the `Server` property in the D-Bus interface to `Client`. The rather strange language in use has it that a player like iTunes is a "client" of the AirPlay device like Shairport Sync, which is therefore considered the "server". The newly-renamed "Client" property is the IP number of the player. 89 90Version 3.3.5 91==== 92 93**Bug Fixes** 94* Fix a crashing bug if output format `S24` was chosen. Thanks to [artenverho](https://github.com/artenverho) for reporting. Fixes Issue [#927](https://github.com/mikebrady/shairport-sync/issues/927). 95* Fix a bug whereby if `Loudness` was enabled through the D-Bus interface, the output would be muted until the volume was changed. 96 97**Enhancements** 98* D-Bus interface enhancements: add `Convolution`, `ConvolutionGain` and `ConvolutionImpulseResponseFile` properties to the D-Bus interface. These properties can be set and changed at any time, even while playing. Implements the suggestion in Issue [#929](https://github.com/mikebrady/shairport-sync/issues/929). Thanks to [corrpel](https://github.com/corrpel) for the suggestion. 99* Update the [sample dbus commands](https://github.com/mikebrady/shairport-sync/blob/master/documents/sample%20dbus%20commands) document. 100 101**Pesky Changes** 102* D-Bus interface change: the D-Bus `LoudnessFilterActive` property has been changed to `Loudness`. The sample D-Bus client has been updated accordingly. 103 104Version 3.3.4 105==== 106 107This is Version 3.3.3 with a small compilation error fixed. 108 109Version 3.3.3 110==== 111 112**Bug Fixes** 113* Fixes a deferred crash that occurred in Ubuntu 14.04: the `shairport-sync` daemon would silently die after a fairly long period. It typically happened just after a DHCP address was renewed. The problem seemed to be related to having more than one `avahi` threaded polling loop (though this isn't documented anywhere). The fix was to consolidate the `avahi` stuff down to one threaded polling loop. Addresses issue [#895](https://github.com/mikebrady/shairport-sync/issues/895). Thanks to [Hans (the) MCUdude](https://github.com/MCUdude) for reporting and for initial troubleshooting. 114 115* Fixes a potential crash when an incomplete `fmtp` parameter set is sent by the requesting client. Thanks to [Angus71](https://github.com/Angus71) for the fault report and for the repair. 116 117* Fixed a potential crash -- if a plain HTTP packet (in fact, any packet that didn't have an RTSP-style header) was sent to the TCP session port (usually port 5000), Shairport Sync would crash! Thanks to @[dubo-dubon-duponey](https://github.com/dubo-dubon-duponey) for reporting. Fixes [#921](https://github.com/mikebrady/shairport-sync/issues/921). 118 119* A fix ensures the hardware mixer of an `alsa` device is detected and initialised before responding to the first volume setting. 120 121* Fixes were made to the MPRIS and native D-Bus interfaces. In particular, situations where artwork is absent are better handled, and the remote interface and advanced remote interface `availability` properties should be more resilient in the face of network problems. Addresses issue [#890](https://github.com/mikebrady/shairport-sync/issues/890). Improvements were made to the detection of the remote services available when an audio source is playing. If the source is minimally compatible, e.g. iOS, Shairport Sync's `org.gnome.ShairportSync.RemoteControl` native `dbus` interface becomes "`available`". If the source is iTunes, then the `org.gnome.ShairportSync.AdvancedRemoteControl` interface also becomes `available`. Artwork, metadata, status and limited remote control facilities are accessible through these interfaces when they are in the `available` state. Thanks to [exoqrtx](https://github.com/exoqrtx) for bringing these issues to light and for testing. 122 123* Fixes an error whereby the `'pvol'`volume metadata was no longer sent if Shairport Sync was configured to ignore volume control information coming from the audio source. Addresses issue [#903](https://github.com/mikebrady/shairport-sync/issues/903). Thanks to [Jordan Bass](https://github.com/jorbas) for reporting the regression and for identifying the commit and code in which the regression occurred. 124 125**Enhancements** 126* Instead of returning `EXIT_FAILURE`, return `EXIT_WITH_SUCCESS` on early exit with either "version" (`–version` or `-V`) or "help" (`–help` or `-h`) arguments. Thanks to [Henrik Nilsson](https://github.com/henriknil) for the patch. 127 128* Normalises the `'pvol`' volume outputs so that when both the software and hardware attenuators are in use to extend the overall attenuation range, the maximum output level corresponds to the maximum output level of the hardware mixer. 129 130* Add the option of including the file and line number of each log entry's source. The option is on by default and is settable in the configuration file and in the `dbus` interface. 131 132* Rewrite the logic for identifying missing packets of audio and for asking for resends. It seems more robust -- there was a suspicion of the previous logic that resend requests were not made for some missing packets. In addition, requests for resends of continuous sequences of packets are rolled into one. 133 134* Expose the advanced settings controlling the resend request logic. The new settings are in the `general` section: 135 * `resend_control_first_check_time` is the time allowed to elapse before a packet is considered missing, defaulting to 0.1 sec. UDP packets don't always arrive in order and they don't need to be re-requested just because they arrive out of sequence. Essentially, therefore, this parameter is to prevent needless resend requests for packets that are already in transit. 136 * `resend_control_check_interval_time` is the interval between repeated requests for a missing packet, defaulting to 0.25 seconds. 137 * `resend_control_last_check_time` is the time by which the last check should be done before the estimated time of a missing packet's transfer to the output buffer, defaulting to 0.1 seconds. In other words, if a packet is still missing 0.1 seconds before it is due to be transferred to the DAC's output buffer, don't bother asking for a resend. 138 139* Exposes two advanced `metadata` settings related to handling cover art: 140 * The setting `cover_art_cache_directory` allows you to specify where cover art files will be cached if Shairport Sync has been built with native D-Bus, MPRIS or MQTT support. The default is `/tmp/shairport-sync/.cache/coverart`. If you set it to an empty list: `""`, caching is disabled. This might be useful in, say, an embedded device, or wherever you want to minimise file writing. 141 * The setting `retain_cover_art` is part of the `diagnostics` group. Set it to `"yes"` to retain cover art cached by the D-Bus, MPRIS or `mqtt` interfaces. Your directory may fill up if you leave it set! 142 143Version 3.3.2 144=== 145**Bug Fixes** 146* Fix a bug that sometimes caused a crash when a service name was specified in the configuration file. The fix was to be more systematic in allocating and deallocating memory for temporary strings. Thanks to [Chris Boot](https://github.com/bootc), [Ari Sovijarvi](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925577#5), [Bernhard Übelacker](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925577#10) and [Jeroen Massar](https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925577#17) for the bug report. Fixes [Debian Bug report #925577]( https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=925577) and supercedes [Pull Request #879](https://github.com/mikebrady/shairport-sync/pull/879). 147* Correct some documentation typos – thanks again to [Chris Boot](https://github.com/bootc). 148 149**Enhancements** 150 151Add some settings for controlling the disable_standby_mode. 152* The first setting is the `disable_standby_mode_silence_threshold`, which is the amount of audio in the output device's hardware buffer. It should normally be close to the value given in the `audio_backend_buffer_desired_length_in_seconds` setting. If it drops to this value, silence is added to the buffer to prevent the output device from becoming idle. 153* The second new setting is the `disable_standby_mode_silence_scan_interval` which is the time between checks of the output device's hardware buffer. 154 155Version 3.3.1 156=== 157 158**Bug Fixes** 159* Fix a bug in the MQTT documentation and add sanity checking for the port chosen -- thanks to [David Crook](https://github.com/idcrook). 160* Fix a bug that caused manual format and rate setting to be ignored -- thanks to [Jörg Krause](https://github.com/joerg-krause). 161* Add missing support for format settings S24_LE, S24_BE, S32_LE and S32_BE. 162* Fix a bug that caused dither to be too loud. 163* Fix error message for invalid `disable_standby_mode` choice -- thanks to [Tim Curtis](https://github.com/moodeaudio) at [Moode Audio](https://moodeaudio.org). 164 165Version 3.3 166==== 167Version 3.3 is focused on stability improvements and also offers a number of enhancements. Here is a selection of the most important: 168 169**Enhancements** 170* Automatic `alsa` output device speed and format selection. The greatest bit depth and the lowest multiple of 44,100 frames per second settings are chosen automatically by default. Manual selection is still available. 171* Automatic interpolation selection. If the CPU is fast enough, the better-quality `soxr` interpolation method is chosen. Otherwise `basic` interpolation is used. Manual selection is still available. 172* A new `active` state. New hooks are provided to execute programs before entering and after leaving the `active` state which covers sequences of play sessions separated by short intervals. This simplifies amplifier switch-on and switch-off, for example. 173* DAC crackle minimisation. This new feature is intended to minimise pops and crackles caused in some Digital to Analog Converters (DACs) when they transition between active and idle or standby operation. The new `alsa`-only `disable_standby_mode` prevents the DAC entering the standby mode by keeping it active, either permanently or while Shairport Sync is in the active state. This feature is switched off by default. 174* A new backend to interface Shairport Sync to [Jack Audio](http://jackaudio.org), thanks to the work of [Jörn Nettingsmeier](https://github.com/nettings). 175* A new [MQTT](https://en.wikipedia.org/wiki/MQTT) client interface, thanks to the work of [Till Zimmermann](https://github.com/tillz). 176* Changes in logging -- now you should add `-u` to direct log entries to STDERR (typically the console) rather than the system log. For example, to get logs of verbosity 1 to appear on the console: `$ shairport-sync -v -u`. 177* The help menu now lists all `alsa` output devices found. 178* Better support for big-endian CPUs. 179* Shairport Sync accepts AirPlay streams containing CD-quality uncompressed PCM. 180 181**Bug Fixes** 182* Lots of bugs – too many to list here – have been fixed that significantly improve the stability of Shairport Sync. The full list is in the Release Notes. 183 184For more details of enhancements and bug fixes, please see the [Release Notes for 3.3](https://github.com/mikebrady/shairport-sync/releases/tag/3.3). Special thanks to [gibman](https://github.com/gibman). 185 186Version 3.2.2 187==== 188Please see the [Release Notes for 3.2](https://github.com/mikebrady/shairport-sync/releases/tag/3.2). 189 190**Enhancement** 191* Latency calculations have been updated to accommodate changes in iOS 12 and AirPlay connections from macOS Mojave. Thanks to [artenverho](https://github.com/artenverho) who first reported the issue. 192 193* Formatting of the settings file `shairport-sync.conf` has been fixed, thanks to the work of [roblan](https://github.com/roblan). 194 195**Bug Fix** 196* Fixed a problem that prevented the `run_this_when_volume_is_set` script or program from running when the volume control is changed. Thanks to [shaven](https://github.com/shaven) for the report. 197 198Version 3.2.1 199==== 200 201**Bug Fix** 202* Fix a bug that was causing problems when `soxr` interpolation was chosen. Problems included instability during or after a play session and possibly an extremely slight click on very loud audio. Thanks are due to [hanaguro](https://github.com/hanaguro), [FnasBas](https://github.com/FnasBas), [priitohlo](https://github.com/priitohlo), [David Krmpotić](https://github.com/davidhq) and [artenverho](https://github.com/artenverho). 203 204Version 3.2 205==== 206Version 3.2 is equivalent to 3.2RC13. 207 208Version 3.2RC13 209==== 210**Adjustment** 211* Reduce the number of attempts that will be made to have a missing packet resent. It seems that in some situations on poor networks, the number of resend requests was causing problems. 212 213Version 3.2RC12 214==== 215**Enhancement** 216* Add a "ProgressString" property to the native D-Bus interface. 217 218**Bug Fix** 219* Some code added in RC11 to monitor mutex lock times was causing some annoying issues -- fixed. 220 221Version 3.2RC11 222==== 223**Bug Fixes** 224 225* Restore compatibility with Synology AudioStation/5.2. Thanks to [Jörg Krause](https://github.com/joerg-krause) for identifying both the issue itself and the likely location of the fix needed. It's not clear if the problem lies with Shairport Sync or Synology – the fix was to ensure that an RTSP reply was sent in one `SEND` call, which shouldn't be important. 226* Fix a bug that was causing Shairport Sync to hang very occasionally when a play session was ending. This seems to occur under rare circumstances, therefore many thanks to [David Krmpotić](https://github.com/davidhq) both for finding the problem and for his patience in trying out different theories before the bug was finally identified. More long-term work is probably needed here. 227 228Version 3.2RC10 229==== 230**Compatibility Adjustment** 231 232* Disable the use of all hardware mute mechanisms by default, for compatibility with other applications using the same output card. 233* Rename the `alsa` setting `mute_using_playback_switch` to `use_hardware_mute_if_available` and make it control volume-based mute as well as playback-switch-based mute. 234 235Version 3.2RC9 236==== 237**Bug Fix** 238 239* Restore the correct pathname for the Shairport Sync PID file used in FreeBSD and System V Linux installations. 240 241Version 3.2RC8 242==== 243**Bug Fixes** 244 245* Fix a bug causing a play session to hang up on Cygwin 64. Fix a bug that might cause excessive resend requests. Fix a number of other (apparently) silent bugs. 246 247Version 3.2RC7 248==== 249**Bug Fixes** 250 251* A very subtle bug that would occasionally cause a loud 80 millisecond buzz when a new track was selected has been located and fixed. Thanks to [mistipen](https://github.com/mistepien) and [artenverho](https://github.com/artenverho) for help with this. 252 253Version 3.2RC6 254==== 255**Bug Fixes** 256 257* Restores audio sync with videos on older versions of iOS (prior to iOS 11.2) and macOS by restoring the old way of determining latency for clients identifying with AirPlay user agent strings having a version of 353 (iOS 11.1.2) or earlier. Thanks to [Mmoi-Fr](https://github.com/Mmoi-Fr) for help with this. 258 259Version 3.2RC5 260==== 261**Bug Fixes** 262* When errors occur sending resend requests, back off for 0.5 seconds, rather than 10 seconds, and make the code actually work. 263* Make the configuration options for including the dbus interface and the mpris interface be `--with-dbus-interface` and `--with-mpris-interface` as expected, not `--with-dbus` and `--with-mpris` as they actually were. 264 265Version 3.2RC4 266==== 267**Bug Fixes** 268* 3.2RC4 now sends resend requests (correctly) in the control channel rather than (incorrectly) over the audio channel as before. This makes it compatible with AirAudio and also makes it conform to the [Unofficial AirPlay Protocol Specification](https://nto.github.io/AirPlay.html). This bug went unnoticed for so long because other AirPlay sources accept resend requests in the audio channel. Thanks to [funtax](https://github.com/funtax) and to [Janusz Kowalczyk](https://github.com/kowalcj0) for bringing the issue to the fore. 269 270Version 3.2RC3 271==== 272**Enhancements** 273* Lost UDP packet resending code improved for better performance on busy or congested networks. 274 275**Bug Fixes** 276* 3.2RC3 removes fixes some important and long-standing bugs that could make Shairport Sync less resilient on noisy or poor quality networks. 277 278Version 3.2RC2 279==== 280**Bug Fixes** 281* 3.2RC2 makes Shairport Sync work with AirAudio, removing a crashing bug, and includes some more debugging code. 282 283Version 3.2RC1 284==== 285**Enhancements** 286* Shairport Sync now offers an IPC interface via D-Bus. It provides an incomplete but functional MPRIS interface and also provides a native Shairport Sync interface. Both provide some metadata and some remote control. The native D-Bus interface permits remote control of the current AirPlay or iTunes client. It includes status information about whether the remote control connection is viable or not, i.e. whether it can still be used to control the client. A remote control connection to the audio client becomes valid when the client starts AirPlaying to Shairport Sync. The connections remains valid until the audio source deselects Shairport Sync for AirPlay, or until the client disappears, or until another client starts AirPlaying to Shairport Sync. After 15 minutes of inactivity, the remote control connection will be dropped. 287* OpenBSD compatibility. Shairport Sync now compiles on OpenBSD -- please consult the OpenBSD note for details. 288* A new `general` option `volume_control_profile`, for advanced use only, with two options: `"standard"` which uses the standard volume control profile -- this has a higher transfer profile at low volumes and a lower transfer profile at high volumes -- or `"flat"` which uses a uniform transfer profile to linearly scale the output mixer's dB according to the AirPlay volume. 289* Some DACs have a feature that the lowest permissible "attenuation" value that the built-in hardware mixer can be set to is not an attenuation value at all – it is in fact a command to mute the output completely. Shairport Sync has always checked for this feature, basically in order to ignore it when getting the true range of attenuation values offered by the mixer. 290However, with this enhancement, Shairport Sync can actually use this feature to mute the output where appropriate. 291* Added compatibility with [Swinsian](https://swinsian.com), a Mac music player. 292 293**Bug Fixes** 294* Better AirPlay synchronisation. Older versions of Shairport Sync added an 11,025 frame (0.25 seconds) offset to all the latencies negotiated with the sender. This seems now incorrect for AirPlay sources. Accordingly, the logic Shairport Sync uses to determine the extra delay has been revised. The result is better sync with videos, e.g, YouTube, while iTunes and ForkedDaapd synchronisation is unaffected. 295* Much faster termination of a play session, leading to increased stability playing YouTube audio, etc. 296* Improved resynchronisation logic should improve performance with slow-to-download YouTube videos. 297* Dithering is now off when ignore_volume_control is true. Thanks to [yejun](https://github.com/yejun) for working on this. 298* Better compatibility with TuneBlade -- Shairport Sync honours the latency settings properly now. 299* Fix timing error when using Airfoil as a source. 300* Better handling of missing timing packets. 301* Shairport Sync will now log an unexpectedy dropped or faulty RTSP connection. This might be useful on noisy networks. 302* Better volume level continuity. In recent versions of iOS (11.2) and mac OS (10.13.2), when play is resumed after a pause, the volume level is not always restored, and, if software volume control is being used, Shairport Sync plays at full volume. This issue has been addressed by storing the last airplay volume setting when a play session ends and using it as a default when a new play session begins. 303* Better mixer compatibility. A bug in the hardware volume control affected output devices that have hardware mixers but that do not allow the volume to be set in dB. One example is the Softvol plugin in ALSA. Shairport Sync failed silently when presented with such a device when hardware volume control is enabled: the volume events have no effect. The bug has been fixed by adding two missing lines of code to the `init()` function in `audio_alsa.c`. Thanks to [Jakub Nabaglo](https://github.com/nbgl) for finding and fixing the bug. 304* A number of bug fixes due to [belboj](https://github.com/belboj). Many thanks for these! 305* Enhancements to the handling of quit requests by threads, thanks(again) to [belboj](https://github.com/belboj)! 306 307**Other Changes** 308* `clip` and `svip` metadata messages are now only generated for a play connection, not for all connections (e.g. connections that just enquire if the service is present). 309* `pfls` and `prsm` metadata messages are less frequent, especially when a play session starts. 310* Shairport Sync now uses about an extra half megabyte of RAM for compatibility with TuneBlade's option to have a very long latency -- up to five seconds. 311* Only ask for missing packets to be resent once, and if any error occurs making the request, stop for 10 seconds. 312* Include the `-pthread` flag -- including the pthread library with `-lpthread` isn't always enough. 313* Add optional timing annotations to debug messages -- see the new settings in the diagnostic stanza of the configuration file. 314 315**Updated Documentation** 316* CAR INSTALL and OPENBSD notes added. 317* Improvements in the documentation relating to scripts -- thanks to [Niklas Janz](https://github.com/Alphakilo). 318* Typo fix! Thanks to [corbinsantin](https://github.com/corbinsantin). 319 320 321 322Version 3.1.7 323==== 324* Stable 3.1.5 and 3.1.6 skipped to synchronise the shairport-sync.spec file contents with the release. 325 326**Enhancement** 327* The metadata output stream can include a `dapo` message carrying the DACP port number to be used when communicating with the DACP remote control. This might be useful because the port number is actually pretty hard to find and requires the use of asynchronous mdns operations. You must be using the Avahi mdns back end. 328 329Version 3.1.4 330==== 331 332**Security Update** 333 334* The version of `tinysvcmdns` bundled in Shairport Sync has a buffer overflow bug: *"An exploitable heap overflow vulnerability exists in the tinysvcmdns library version 2016-07-18. A specially crafted packet can make the library overwrite an arbitrary amount of data on the heap with attacker controlled values. An attacker needs send a dns packet to trigger this vulnerability."* The vulnerability is addressed by additional checking on packet sizes. See also [CVE-2017-12087](https://bugs.launchpad.net/bugs/cve/2017-12087) and [Vulnerability in tinysvcmdns](https://bugs.launchpad.net/ubuntu/+source/shairport-sync/+bug/1729668). 335Thanks and [Chris Boot](https://github.com/bootc) for fixing this bug. 336 337**Enhancement** 338* The metadata output stream can include a `dapo` message carrying the DACP port number to be used when communicating with the DACP remote control. This might be useful because the port number is actually pretty hard to find and requires the use of asynchronous mdns operations. You must be using the Avahi mdns back end. 339 340**Bug Fix** 341 342* Somewhere in version 3.x, the `softvol` plugin got broken as the volume change is not applied anymore. Turned out that, for the `softvol` plugin, no `volume()` and `parameters()` are defined. Thanks to [Jörg Krause](https://github.com/joerg-krause) for locating and fixing this bug. 343 344Version 3.1.3 345==== 346 347**Bug Fixes** 348* Fixed a bug that prevented Shairport Sync from starting automatically on systems using the System V startup system (e.g. Ubuntu 14.04). The problem was that the directory to be used – `/var/run/shairport-sync/` – was deleted on power down and needed to be recreated on startup. In it's absence, Shairport Sync would not start and would report a mysterious daemon error \#2. 349 350Version 3.1.2 351==== 352 353Shairport Sync is more stable playing audio from YouTube and SoundCloud on the Mac. 354 355**Pesky Changes You Should Not Ignore** 356* When you update from a previous version of Shairport Sync, your output device may have been left in a muted state. You should use a command line tool like `alsamixer` or `amixer` to unmute the output device before further use. 357 358**Change of Default** 359* The default value for the `alsa` setting `mute_using_playback_switch` has been changed to `"no"` for compatibility with other audio players on the same machine. The reason is that when this setting is set to `"yes"`, the output device will be muted when Shairport Sync releases it. Unfortunately, other audio players using the output device expect it to be unmuted, causing problems. Thanks to [Tim Curtis](https://github.com/moodeaudio) at [Moode Audio](http://moodeaudio.org) and [Peter Pablo](https://github.com/PeterPablo) for clarifying the issue. 360 361**Bug Fixes** 362* Fixed bugs that made Shairport Sync drop out or become unavailable when playing YouTube videos, SoundCloud streams etc. from the Mac. Background: there has been a persistent problem with Shairport Sync becoming unavailable after playing, say, a YouTube clip in a browser on the Mac. Shairport Sync 3.1.2 incorporates a change to how certain AirPlay messages are handled. Introduced in nascent form in 3.1.1, further follow-on changes have improved the handling of player lock and have simplified and improved the handling of unexpected loss of connection. Shairport Sync also now works properly with SoundCloud clips played in a browser on the Mac. 363* Using [infer](https://github.com/facebook/infer/blob/master/README.md), a number of silent issues have been detected, such as not checking some calls to `malloc` to ensure the response is not NULL. Most of these have been addressed by additional checks. 364 365Version 3.1.1 366==== 367 368**Bug Fixes** 369* A bug in the `sndio` backend has been fixed that caused problems on some versions of Linux. 370* A change has been made to how Shairport Sync responds to a `TEARDOWN` request, which should make it respond better to sequences of rapid termination and restarting of play sessions. This can happen, for example, playing YouTube videos in Safari or Chrome on a Mac. 371* Choosing `soxr` interpolation in the configuration file will now cause Shairport Sync to terminate with a message if Shairport Sync has not been compiled with SoX support. 372* Other small changes. 373 374Version 3.1 375==== 376Version 3.1 brings two new backends, optional loudness and convolution filters, improvements in non-synchronised backends, enhancements, stability improvements and bug fixes. 377 378**New Features** 379* A `sndio` backend gives Shairport Sync native fully synchronised output on OpenBSD and FreeBSD, thanks to the work of [Tobias Kortkamp (t6)](https://github.com/t6). 380* A `pa` backend now allows Shairport Sync to provide synchronised output on PulseAudio-equipped systems -- many desktop Linuxes use PulseAudio as their sound manager. 381* Optional loudness and convolution filters can be incorporated in the audio processing chain, thanks to the fantastic work of [yannpom](https://github.com/yannpom). 382* A volume-change program hook `run_this_when_volume_is_set` has been added to the `general` settings stanza to execute an application whenever the volume is changed. 383 384**Pesky Changes You Should Know About** 385* The `audio_backend_buffer_desired_length_in_seconds` and `audio_backend_latency_offset_in_seconds` settings have been moved from individual backend stanzas to the `general` stanza. They now have an effect on every type of backend. 386* If you are using a System V (aka `systemv`) installation, please note that the default location for PID file has moved -- it is now stored at `/var/run/shairport-sync/shairport-sync.pid`. This change is needed to improve security a little and to improve compatibility across platforms. If you're not doing anything strange, this should make no difference. 387 388**Enhancements** 389* Resynchronisation, which happens when the synchronisation is incorrect by more than 50 ms by default, should be a lot less intrusive when it occurs – it should now either insert silence or skip frames, as appropriate. 390* The Linux installer has been improved and simplified and a FreeBSD installer introduced. 391* A new setting, `audio_backend_silent_lead_in_time`, allows you to set the duration of the period of silence played (the "silent lead-in") before a play session starts. 392* A new command-line option, `--logOutputLevel`, allows you to output the volume levels to the log whenever they are changed. This may be useful during setup. 393* Improvements have been made to the handling of large items of metadata over UDP. 394* A new command line option, `-j`, demonizes Shairport Sync without creating a PID file. 395* A new `alsa`-only setting, `mute_using_playback_switch`, is available for advanced use. 396* Other minor enhancements. 397 398**Bug Fixes** 399* Stability improvements. More care has been taken (!) to make code thread-safe, resulting in improved stability. 400* Conversion from stereo to mono has been fixed to avoid clipping while preserving full resolution. Thanks to [Robert Jones (RobDeBagel)](https://github.com/RobDeBagel) for bringing this to notice. 401* Short intrusions of audio at the start of a new session from the end of the previous session have been eliminated. 402* Many (many!) miscellaneous bugs fixed. 403 404Version 3.0.2 405==== 406**Bug Fixes** 407* Fixed bugs in the `ao`, `pulseaudio` and `sndio` back ends. Basically they were expecting default sample rate and depth information, and were terminating when they saw explicit rate and depth data. 408 409Version 3.0.1 410==== 411This update fixes one alarming and potentially very noisy bug and restores the identification of Shairport Sync as "ShairportSync" so that TuneBlade recognises it as an open source application. 412**Bug Fixes** 413* Fixed a bug that was causing Shairport Sync to possibly make a very loud and alarming noise whenever an audio frame was missing. 414* In 2.8.6, a change was made to the way Shairport Sync identified itself, so that it could be recognised by TuneBlade as an open source application and treated preferentially. That change was inadventently lost in the transition from 2.8.6 to 3.0. Now it's restored. 415 416Version 3.0 417==== 418 419Big Update 420---- 421Version 3 brings in support for 24-bit and 32-bit (and 8 bit!) DACs and for DACs running at multiples of 44,100 samples per second. 422 423The most obvious audible change is if you are using software volume control and can take advantage of 32- or 24-bit DACs. Dithering can now occur on a 32-bit or 24-bit sample rather than on a 16-bit sample, making the noise floor very much lower. This is the case, for example, with a Pimoroni PHAT DAC. 424 425Here is the list of new features: 426 427**New Features** 428* 8-bit, 16-bit, 24-bit, 24-bit three-byte (S24_3LE and S24_3BE) and 32-bit output to ALSA devices. 429* 44,100, 88,200, 176,400 and 352,800 sample per second output. This is done using simple upsampling. It's only worth doing if 44,100 samples per second output is not available. 430* Internal processing including software volume control and interpolation is done after sample size and rate conversion. 431* Apple ALAC decoder support. This needs the `libalac` library, available at [ALAC](https://github.com/mikebrady/alac), to be installed. Add the flag `--with-apple-alac` to the `./configure` arguments. Then you can choose the Apple ALAC decoder in the configuration file. 432* Support for `mbed TLS` has been added and the use of `PolarSSL` is deprecated, as `mbed TLS` is a development of `PolarSSL` and `PolarSSL` itself is not being developed further. 433* Choose Network Interface. Add a new setting, for advanced users only, in the `general` section. Use the `interface` setting to allow you to specify the interface on which to provide the AirPlay service. Omit the setting to get the default, which is to choose the interfaces automatically. 434* Set Max Volume. Add a new setting, for advanced users only, in the `general` section. Use the `volume_max_db` setting to allow you to specify the maximum level to set on the hardware mixer (if chosen) or the built-in software mixer otherwise. The software mixer's range is 0.0 dB to -96.1 dB. The setting must be a number with a decimal point, e.g. 21.3. 435* An experimental new back end for `libsoundio`, a C library for cross-platform real-time audio input and output. Many thanks to [Serg Podtynnyi](https://github.com/shtirlic). Please see https://github.com/mikebrady/shairport-sync/pull/433 for more details. 436 437 438Pesky Changes You Cannot Ignore 439---- 440* Processor load is up by about 11%. 441* Settings have changed -- basically, any timings that were denominated in frames are now in seconds. Please refer to the shairport-sync.conf.sample file for details. 442* Sox-based interpolation at higher sample rates may overload your CPU -- you might have to choose between higher sample rates and sox-based interpolation. 443 444 445Version 3.0rc0 – Release Candidate 0 446---- 447Note: all Version 3 changes are summarized above. 448 449**New Feature** 450* An experimental new back end for `libsoundio`, a C library for cross-platform real-time audio input and output. Many thanks to [Serg Podtynnyi](https://github.com/shtirlic). Please see https://github.com/mikebrady/shairport-sync/pull/433 for more details. 451 452**Other changes** 453* Updates to `man` page and [README](https://github.com/mikebrady/shairport-sync/blob/development/README.md). Reports of typos or suggestions for improvement are welcome! 454 455Version 3.0d24 – Development Version 456---- 457Note: all Version 3 changes are summarized above. 458 459**New Feature** 460* Set Max Volume. Add a new setting, for advanced users only, in the `general` section. Use the `volume_max_db` setting to allow you to specify the maximum level to set on the hardware mixer (if chosen) or the built-in software mixer otherwise. The software mixer's range is 0.0 dB to -96.1 dB. The setting must be a number with a decimal point, e.g. 21.3. 461 462Version 3.0d23 – Development Version 463---- 464Note: all Version 3 changes are summarized above. 465 466**New Feature** 467* Choose Interface. Add a new setting, for advanced users only, in the `general` section. Use the `interface` setting to allow you to specify the interface on which to provide the AirPlay service. Omit the setting to get the default, which is to choose the interfaces automatically. 468 469Version 3.0d22 – Development Version 470---- 471Note: all Version 3 changes are summarized above. 472 473**Bug Fix** 474* Fixed a bug which prevented successful building in the OpenWrt build system. The problem was caused by an `#include apple_alac.h` in `player.c` which was actioned even if the apple alac decoder was not selected. This caused the OpenWrt build system to expect the standard C++ library – required by the apple alac code – to be referenced, but it was not specified on the build manifest and therefore stopped the build. The solution was to make the `#include` conditional on selecting the apple alac decoder. 475 476Version 3.0d21 – Development Version 477---- 478Note: all Version 3 changes are summarized above. 479 480**Bug Fix** 481* Fixed a bug which turned off resync by default. Duh. 482 483Version 3.0d20 – Development Version 484---- 485Note: all Version 3 changes are summarized above. 486 487**Bug Fix** 488* Fix a small and generally silent error in configure.ac so that it only looks for the systemd directory if systemd has been chosen. It caused a warning when cross-compiling. 489 490Version 3.0d19 – Development Version 491---- 492Note: all Version 3 changes are summarized above. 493 494**New Feature** 495* Reduces processor load back to V2.X levels by using a precalculated array of pseudorandom numbers to do dithering. Doesn't seem to make any audible difference. 496 497Version 3.0d18 – Development Version 498---- 499Note: all Version 3 changes are summarized above. 500 501**New Features** 502* 8-bit, 16-bit, 24-bit, 24-bit three-byte (S24_3LE and S24_3BE) and 32-bit output to ALSA devices. (Other back ends are not updated yet.) 503* 44,100, 88,200, 176,400 and 352,800 sample per second output. This is done using simple upsampling. 504* Internal processing including software volume control and interpolation is done after sample size and rate conversion. 505* Apple ALAC decoder support. This needs the `libalac` library, available at [ALAC](https://github.com/mikebrady/alac). Add the flag `--with-apple-alac` to the `./configure` arguments. Then you can choose the Apple ALAC decoder in the configuration file. 506* Support for `mbed TLS` has been added and the use of `PolarSSL` is deprecated, as `mbed TLS` is a development of `PolarSSL` and `PolarSSL` itself is not being developed further. 507* Settings that were denominated in frames are now deprecated but still honoured. Deprecation warnings are issued. 508 509Pesky Changes You Cannot Ignore 510==== 511* Settings have changed -- basically, any timings that were denominated in frames are now in seconds. Please refer to the shairport-sync.conf.sample file for details. 512* Sox-based interpolation at higher sample rates may overload your CPU -- yopu might have to choose between higher sample rates and sox-based interpolation. 513 514**Bugs** 515* Documentation is not updated. 516 517Version 2.8.6 – Stable Candidate 518---- 519 520**Enhancements** 521* This release contains a small change – it identifies itself as a ShairportSync device rather than an AirPort device. This should make it possible for Tuneblade, and possibly other players, to recognise it correctly. 522 523Version 2.8.5 – Stable Version 524---- 525This release includes bug fixes and minor enhancements and is recommended for all users. 526 527Note: if you're upgrading, there is a new `./configure` option: 528==== 529The build process now uses the directory path `sysconfdir` to determine where to place the configuration file `shairport-sync.conf`. 530The default value for `sysconfdir` is `/usr/local/etc` which is used in the BSD family, whereas `/etc` is normally used in Linux. 531To retain the present behaviour of Shairport Sync, *you must add an extra parameter to the `./configure... ` command.* The parameter you must add is `--sysconfdir=/etc`. (This has been added to the sample configuration command line in README.md.) 532 533The enhancements and bug fixes in 2.8.5 were made in versions 2.8.4.1 to 2.8.4.8 inclusive. Please read below for the full list. 534 535For advice on updating an installation you built yourself, 536please visit the [UPDATING](https://github.com/mikebrady/shairport-sync/blob/master/UPDATING.md) page. 537 538Version 2.8.4.8 – Development Version 539---- 540**Enhancements** 541* Add a new metadata item `clip` (for `CL`ient `IP`). This item is a string comprising the IP number of the "client", and is sent when a play session is starting. The "client" is the sender of the audio stream, e.g. iTunes on a Mac, or the Music player in iOS. 542* When synchronisation has been disabled on the ALSA device (you should only do this for testing), Shairport Sync now refrains from asking for buffer length information from the device. 543 544Version 2.8.4.7 – Development Version 545---- 546 547* This update means the build process now uses the directory path `sysconfdir` to determine where to place the configuration file `shairport-sync.conf`. The default value for `sysconfdir` is `/usr/local/etc` which is used in the BSD family, whereas `/etc` is normally used in Linux. So, to retain the present behaviour of Shairport Sync, you must add an extra parameter to the `./configure... ` command. The parameter you must add is `--sysconfdir=/etc`. (This has been added to the sample configuration command line in README.md.) 548* Shairport Sync has been updated to use the value of `sysconfdir` to determine where to look for the configuration file. If `sysconfdir` has been left with its default value of `/usr/local/etc`, then Shairport Sync will look for `/usr/local/etc/shairport-sync.conf`. If, as recommended for Linux, `sysconfdir` has been set to `/etc`, then Shairport Sync will look, as before, for `/etc/shairport-sync.conf`. 549 550**Enhancement** 551* The version string output when you use the command-line option `-V` now includes the value of the `sysconfdir`, e.g. `2.8.4.7-OpenSSL-Avahi-ALSA-soxr-sysconfdir:/etc`. 552 553Version 2.8.4.6 – Development Version 554---- 555**Enhancement** 556* Add a new `alsa` configuration setting: `use_mmap_if_available` to control the use of mmap. The default is `"yes"` -- see [#351](https://github.com/mikebrady/shairport-sync/issues/351). 557 558Version 2.8.4.5 – Development Version 559---- 560**Enhancement** 561* Handle varying packet lengths -- this makes it compatible with the HTC Connect, HTCs AirPlay implementation. Thanks to [Jörg Krause](https://github.com/joerg-krause) for his detective work, and see [#338](https://github.com/mikebrady/shairport-sync/issues/338). 562 563Version 2.8.4.4 – Development Version 564---- 565**Enhancement** 566* Use alsa direct access (mmap) feature to improve performance if mmap is supported. Thanks to [Yihui Xiong](https://github.com/xiongyihui). 567 568Version 2.8.4.3 – Development Version 569---- 570**Bug Fix** 571 572* Set the RTSP socket to close on `exec()` of child processes; otherwise, background `run_this_before_play_begins` or `run_this_after_play_ends` commands that are sleeping prevent the daemon from being restarted because the listening RTSP port is still in use. Fixes [#329](https://github.com/mikebrady/shairport-sync/issues/329). 573 574Version 2.8.4.2 – Development Version 575---- 576**Bug Fixes** 577 578* Fixed an issue where you could not compile the audio_pipe back end without enabling metadata support (thanks to [busa-projects](https://github.com/busa-projects) for reporting the issue). 579* Fixed a few small issues causing compiler warnings in `mdns_dns_sd.c`. 580 581 582**Other** 583* Removed the INSTALL file – it's generated automatically by `autoreconf -fi` anyway – added it to the files to be ignored in `.gitignore` and added a simple `INSTALL.md` file. 584 585Version 2.8.4.1 – Development Version 586---- 587**Bug Fixes** 588 589* Fixed two issues when including support for `pulseaudio`. 590* Corrected two small errors in sample parameters for the UDP metadata stream settings, thanks to [rkam](https://github.com/rkam). 591 592Version 2.8.4 – Stable Version 593---- 594This release includes important bug fixes and minor enhancements and is recommended for all users. No settings need to be changed. For advice on updating an installation you built yourself, please visit the [UPDATING](https://github.com/mikebrady/shairport-sync/blob/master/UPDATING.md) page. 595 596The following is a summary of the bug fixes and enhancements since version 2.8.3. 597 598**Bug Fixes** 599 600* Checks have been added for empty or NULL audio buffers that were causing assertion violations and subsequent abnormal program termination. 601 602* An IPv6 bug has been fixed — a bug in the networking software would not allow an IPv6 link-local connection to be made from a client if Shairport Sync was running on a device with more than one network interface. The solution was to take account of the `config_id` information. 603 604* Some problems have been fixed with the non-blocking write function used to write metadata. 605 606* A bug in the volume control transfer function has been fixed, thanks to [Jörg Krause](https://github.com/joerg-krause). 607 608**Enhancements** 609 610* Shairport Sync now works with [AllConnect/Streambels](http://allconnectapp.com) on Android with password protection. (As with all Android clients, you should set the `drift` to something large, like 500 or 1,000, as the timekeeping of these clients isn't as accurate as that of iTunes, etc.) 611 612* The networking subsystem has been modified to always use the same IP number during a session. Background: the computer Shairport Sync is running on can have many IP numbers active at the same time – various IPv6 numbers and also various IPv4 numbers. During a play session, when Shairport Sync has to create connections back to the source, it would use an automatically-assigned IP number for itself, but that number might not be same as the the number used earlier in the session. From now on, it will always use the same IP number it used when the connection was first established. Thanks to [ejurgensen](https://github.com/ejurgensen) for help with this. 613 614* Experimental support has been added for a softvol plugin, thanks to the work of [Jörg Krause](https://github.com/joerg-krause) -- see [#293](https://github.com/mikebrady/shairport-sync/pull/293). 615 616* A `playback_mode` setting has been added to allow the selection of `stereo` (default) or `mono` playback -- thanks to [faceless2](https://github.com/faceless2). 617 618* The new default service name is now the device's `hostname`, with its first character capitalised (ASCII only). 619 620* Substitutions can now be made in the service name. The following substitutions can be used in the service name: `%h` for the `hostname`, `%H` for the `hostname` with the first letter capitalised, `%v` for the version number and `%V` for the full version string. Maximum length is 50 characters. 621 622* An existing `shairport-sync.service` file will not be overwritten by `sudo make install`. 623 624* The text strings advertising the capabilities of Shairport Sync over Bonjour/Zeroconf/Avahi have been changed and now more closely match those of an AirPort Express Base Station (First Generation). 625 626* It is now possible to set the amount of time to wait for the metadata pipe to become ready for writing. The setting is called `pipe_timeout` in the `metadata` section. Default is 5,000 milliseconds. 627 628* Metadata can now be provided via UDP -- thanks to [faceless2](https://github.com/faceless2). 629 630* Statistics output is more machine readable -- thanks to [Jörg Krause](https://github.com/joerg-krause) 631* The `shairport-sync.spec` file has been updated for compatibility with building Debian packages using `checkinstall` -- thanks to [vru1](https://github.com/vru1). 632 633Version 2.8.3.11 – Development Version 634---- 635**Bug Fix** 636 637Fixed some problems with the non-blocking write function used to write to the metadata pipe. 638 639**Enhancement** 640 641It is now possible to set the amount of time to wait for the metadata pipe to become ready for writing. The setting is called `pipe_timeout` in the `metadata` section. Default is 5,000 milliseconds. 642 643Version 2.8.3.10 – Development Version 644---- 645**Bug Fix** 646 647* Restored metadata feed lost in 2.8.3.7. 648 649Version 2.8.3.9 – Development Version 650---- 651**Enhancements** 652 653* Substitutions can now be made in the service name, i.e. the name that appears in iTunes, etc. The following substitutions can be used in the service name you specify: `%h` for the hostname, `%H` for the hostname with the first letter capitalised, `%v` for the version number and `%V` for the full version string. Maximum length is 50 characters. 654 655* The new default service name is simply the hostname, with its first character capitalised. 656 657* An existing `shairport-sync.service` file will not be overwritten by `sudo make install`. 658 659Version 2.8.3.7 – Development Version 660---- 661**Enhancements** 662 663* Shairport Sync now works with AllConnect/Streambels on Android with password protection. (As with all Android clients, you should set the `drift` to something large, like 500 or 1,000, as the timekeeping of these clients isn't as accurate as that of iTunes, etc.) 664 665* The text strings advertising the capabilities of Shairport Sync over Bonjour/Zeroconf/Avahi have been changed and now more closely match those of an AirPort Express Base Station (First Generation). 666 667Version 2.8.3.6 – Development Version 668---- 669**Bug fix** 670 671An IPv6 link-local connection issue was fixed. A bug in the networking software would not allow an IPv6 link-local connection to be made from a client if Shairport Sync was running on a device with more than one network interface. The solution was to take account of the `config_id` information. 672 673Version 2.8.3.5 – Development Version 674---- 675**Enhancement** 676 677Experimental support for a softvol plugin, thanks to the work of [Jörg Krause](https://github.com/joerg-krause) -- see [#293](https://github.com/mikebrady/shairport-sync/pull/293). 678 679**Bug fix** 680 681Add checks for empty or NULL audio buffers that seem to be causing assertion violations and subsequent abnormal program termination. 682 683Version 2.8.3.4 – Development Version 684---- 685 686**Bug Fix** 687 688The networking subsystem has been modified to always use the same IP number during a session. Background: the computer Shairport Sync is running on can have many IP numbers active at the same time – various IPv6 numbers and also various IPv4 numbers. During a play session, when Shairport Sync has to create connections back to the source, it would use an automatically-assigned IP number for itself, but that number might not be same as the the number used earlier in the session. From now on, it will always use the same IP number it used when the connection was first established. Thanks to [ejurgensen](https://github.com/ejurgensen) for help with this. 689 690 691Changed the `mono` setting for a `playback_mode` setting with two possible values: `stereo` (default) and `mono`. 692 693Version 2.8.3.3 – Deleted 694---- 695 696Version 2.8.3.2 – Deleted 697---- 698 699Version 2.8.3.1 – Development Version 700---- 701Added a new `mono` setting -- thanks to [faceless2](https://github.com/faceless2). Documentation to follow. 702 703Version 2.8.3 – Stable Version 704---- 705A bug in 2.8.2 caused Avahi to fail at startup under some circumstances with older installations. The problem was that sometimes the `regtype` setting would not be initialised properly. 706 707Version 2.8.2 – Stable Version 708---- 709Version 2.8.2 is derived from development version 2.9.5.7 and has stability improvements, bug fixes and a few special-purpose enhancements. 710 711For full details, please refer to the release notes here, back as far as 2.8.1. 712 713Version 2.9.5.7 – Development Version 714---- 715Version 2.9.5.7 contains general bug fixes and enhancements for some special situations. 716 717**Bug Fixes** 718 719* Getting delay and latency information from the `alsa` subsystem has been improved -- bugs fixed, error codes handled better, arithmetic handling (hopefully) better. 720* If latency information is temporarily unavailable from the `alsa` subsystem, skip trying to synchronise until the next time. 721* Some condition variables and a mutex were uninitialised, yikes! Fixed. 722* A bug that set the output volume to maximum at the same time as muting the output has been fixed. AFAIK, this was inaudible, but it was scary looking. 723* Recover from name collisions in Avahi. 724* Detect and handle empty buffers better. 725 726**Enhancements** 727 728* Turn off synchronisation. This is an advanced feature and generally leads to buffer underrun or overrun. 729* Set `alsa` buffer size and `alsa` period size. There are advanced features, mainly for debugging. They may be removed. 730* Change the Zeroconf/Bonjour `regtype` to enable Shairport Sync to continue to run but to be invisible to AirPlay clients. Special purpose usage only. 731* Output total number of packets and the play time of a session when statistics are enabled. 732 733Version 2.9.4 – Development Version 734---- 735Version 2.9.4 corrects some bugs in how Avahi error conditions are handled. 736 737**Bug Fix** 738* During operation, if the network disappeared, Avahi would occasionally report an error. This would cause Shairport Sync to attempt to terminate gracefully (which is the wrong thing to do in the circumstances). However, the termination attempt was actually causing an assertion violation crash. These errors are now simply logged. 739 740Version 2.9.3 – Development Version 741---- 742Version 2.9.3 is 2.8.1 with documentation and version changes to indicate that it's in the development branch. 743 744Version 2.8.1 – Stable Version 745---- 746Version 2.8.1 is derived from development version 2.9.2 and has stability improvements and important bug fixes. 747 748For full details, please refer to the release notes here, back as far as 2.9.1. 749 750Version 2.9.2 – Development Version 751---- 752Version 2.9.2 focuses on further bug fixes and stability improvements. 753* Enhanced stability: an important bug has been fixed in the handling of missing audio frames – i.e. what happens when a frame of audio is truly missing, after all attempts to fetch it have been unsuccessful. The bug would cause Shairport Sync to do an unnecessary resynchronisation, or, if resync was turned off, to jump out of sync. This is a long-standing bug – thanks to [Jörg Krause](https://github.com/joerg-krause) for identifying it. 754* An extra diagnostic has been added which gives the mean, standard deviation and maximum values for inter-packet reception time on the audio port. It may be useful for exploring line quality. 755 756Version 2.9.1 – Development Version 757---- 758Version 2.9.1 focuses on bug fixes and stability improvements. 759* Stability improvements are concentrated on what happens when a play sessions ends and is followed immediately by a new session. This happens in iOS 9.2 when you click to the next track or to the previous track. It also happens playing YouTube videos when a Mac's System Audio is routed through AirPlay. Thanks to [Tim Curtis](https://github.com/moodeaudio) for help with these issues. 760* A workaround for an apparent flushing issue in TuneBlade has been included. Thanks to [gibman](https://github.com/gibman) for reporting this issue. 761* A number of bug fixes have been made to `configure.ac` – thanks to [Jörg Krause](https://github.com/joerg-krause). 762 763Version 2.8 – Stable Version 764---- 765Version 2.8 is derived from version 2.7.10 with slight documentation updates. Here is a summary of changes between the last stable version – 2.6 – and this version. For full details, refer to the release notes here, back as far as 2.7. 766 767**New Feature** 768* For hardware mixers with a restricted range (including many cheaper USB DACS), the general `volume_range_db` can be used to specify a wider range than the hardware provides – the extra range is provided by software. 769 770**Enhancements** 771* The `man` manual and the html version of it are automagically rebuilt if `xml2man` and friends are available. 772* Volume-setting metadata is now sent even when the volume level is to be ignored by Shairport Sync itself. 773* Shairport Sync waits a little longer before asking for missing packets to be resent. Sometimes packets are just arriving slightly out of order and don't need to be asked for again. 774* The build scripts have been modified to be a little more compatible with standard practice. 775* A Continuous Integration (CI) system – Travis CI – is now used to do some limited build checking (thanks guys!). 776* Support added for compiling on Cygwin. 777* Added `rtptime` tags to metadata and picture metadata. 778* Replaced and improved the dither algorithm used with the software volume control. The new dither code gives a two bit peak-to-peak dither based on a Triangular Probability Distribution Function (TPDF). 779* Disabled picture sending if pictures haven’t been asked for. 780 781**Bug fixes** 782* Fixed a bug that prevented Shairport Sync from correctly setting the hardware mixer volume if it had been altered externally. Thanks to [Tim Curtis](https://github.com/moodeaudio) for help with these issues. 783* Modified the shutdown behaviour so that a shutdown followed immediately by a play request is handled better. This was causing iOS 9.2 sometimes to drop the Airplay link between tunes. 784* Fixed a data-alignment bug that would cause a crash in certain circumstances on ARM processors with metadata enabled. 785* Corrected the names for a few settings tags. 786* Fixed some typos and misspellings. 787* Miscellaneous small bug fixes. 788 789Version 2.7.10 -- Development Version 790---- 791**New Feature** 792* If the `ignore_volume_control` setting was `yes`, Shairport Sync really did ignore volume control settings and did not send any volume metadata (i.e. `pvol` coded metadata). Now, while continuing to ignore volume control settings, it sends a `pvol` token where the first number is the AirPlay volume, as before, but the remaining three parameters are set to zero. 793 794Version 2.7.9 -- Development Version 795---- 796**Bug Fix** 797* Oops – brown-bag update. Fixed a crashing bug introduced in the last release, caused by not checking for a hardware mixer before trying to access it, duh. 798 799Version 2.7.8 -- Development Version 800---- 801**Bug Fix** 802* Fixed an issue whereby Shairport Sync did not reset the hardware mixer volume level before resuming playing. The issue was caused by not releasing and later reaquiring the mixer when pausing and resuming. Thanks to [Tim Curtis](https://github.com/moodeaudio) for reporting the issue. 803 804Version 2.7.7 -- Development Version 805---- 806**Enhancements** 807* Add note about the Arch Linux Community repository package `shairport-sync`. Thanks to [Anatol Pomozov](https://github.com/anatol). 808* Shairport Sync doesn't ask for packets to be resent quite so quickly -- it waits about half a second now before asking for missing packets to be resent. 809 810**Bug Fixes** 811* Improved Shairport Sync's behaviour when it's asked to stop a play session and immediately start another. The signalling system used to stop threads was sometimes stopping threads belonging to the new session. This affected iOS 9.2 users going to the next track -- sometimes the player would become unavailable for an instant and disconnect the session. Th problem still happens occasionally. 812* Removed code favouring the use of "public" IPv6 addresses as source addresses when connecting to a distant IPv6 port – Neither OpenWrt nor FreeBSD can use it at present. Also, it's not clear if any problems are being caused by not favouring public IPv6 addresses. 813 814Version 2.7.6 -- Development Version 815---- 816**Bug Fixes** 817* Look for the correct tag name for desired `ao` buffer length: `audio_backend_buffer_desired_length` rather than `audio_backend_buffer_desired_length_software`. 818* Fix a few FreeBSD compilation bugs. 819* Fix a few documentation issues and typos. Thanks to [Chris Boot](https://github.com/bootc). 820 821**Enhancements** 822* Add note about installing to Mac OS X. Thanks to [Serg Podtynnyi](https://github.com/shtirlic). 823* Add automatic rebuild of manpage and html documentation when `xmltoman` and friends are available. Thanks to [Chris Boot](https://github.com/bootc). 824* Favour the use of "public" IPv6 addresses as source addresses when connecting to a distant IPv6 port. 825 826Version 2.7.5 -- Development Version 827---- 828**New Features** 829* Ubuntu PPA files now available at https://launchpad.net/~dantheperson. 830 831**Enhancements** 832* Broaden the use of the value `$PREFIX` instead of the path `/usr/local/bin` during configuration. Thanks to [dantheperson](https://github.com/dantheperson). 833 834Version 2.7.4 -- Development Version 835---- 836**Enhancements** 837* Use the correct method for finding the `systemd` unit path, as recommended by Debian maintainers and 838http://www.freedesktop.org/software/systemd/man/daemon.html#Installing%20Systemd%20Service%20Files. Thanks to [dantheperson](https://github.com/dantheperson). 839* Rather than hardwire the path `/usr/local/bin` as the path to the shairport-sync executable, the value of `$PREFIX` is now used during configuration. Thanks to [Nick Steel](https://github.com/kingosticks). 840* Add some extra diagnostic messages if the hardware buffer in the DAC is smaller than desired. 841* If metadata has been enabled, but if picture sending has not been requested and the source sends pictures anyway, omit them from the metadata feed. Thanks to [Jörg Krause](https://github.com/joerg-krause). 842 843**Bug Fixes** 844* Fixed a data alignment issue in the handling of metadata on some processors. Thanks to [Jörg Krause](https://github.com/joerg-krause). 845* Removed an `assert` which would terminate the program if a malformed packet of data was received. 846* Look for the correct tag name for desired alsa buffer length: `audio_backend_buffer_desired_length` rather than `audio_backend_buffer_desired_length_software`. 847 848Version 2.7.3 -- Development Version 849---- 850**Bug Fix** 851* The dither code was broken in Shairport Sync and was less than ideal anyway. It has been fixed and improved. Dither is added whenever you use the software volume control at less than full volume. See http://www.ece.rochester.edu/courses/ECE472/resources/Papers/Lipshitz_1992.pdf for a very influential paper by Lipshitz, Wannamaker and Vanderkooy, 1992. The dither code in Shairport Sync was inherited from Shairport and does not conform to the recommendations in the paper -- specifically the implementation would give one bit of dither where the paper recommends two bits peak-to-peak. The other thing is that the inherited dither code was actually broken in Shairport Sync. So, the new dither code gives a two bit peak-to-peak dither based on a Triangular Probability Distribution Function (TPDF). It sounds like a very low-level white noise, unmodulated by the audio material. It would be nice if it was even lower, but it's better than listening to the artifacts present when dithering is disabled. 852 853Version 2.7.2 -- Development Version 854---- 855**Bug Fix** 856* Fix a bug that suppressed output of the `rtptime` associated with metadata and with picture information coming from the audio source and passed on via the metadata pipe. 857 858**Other Changes** 859* Added some more information to the log whenever problems are detected with the proposed alsa device. 860 861Version 2.7.1 -- Development Version 862---- 863**Bug Fix** 864* The new volume-extension code was not correctly setting the volume after a pause / resume. Fixed. 865 866Version 2.7 -- Development Version 867---- 868**New Features** 869* Extend the volume range for some DACs. Background: some of the cheaper DACS have a very small volume range (that is, the ratio of the highest to the lowest volume, expressed in decibels, is very small). In some really cheap DACs it's only around 30 dB. That means that the difference between the lowest and highest volume settings isn't large enough. With the new feature, if you set the `general` `volume_range_db` to more than the hardware mixer's range, Shairport Sync will combine the hardware mixer's range with a software attenuator to give the desired range. For example, suppose you want a volume range of 70 dB and the hardware mixer offers only 30 dB, then Shairport Sync will make up the other 40 dB with a software attenuator. One drawback is that, when the volume is being changed, there may be a slight delay (0.15 seconds by default) as the audio, whose volume may have been adjusted in software, propagates through the system. Another slight possible drawback is a slightly heavier load on the processor. 870* Check for underflow a little better when buffer aliasing occurs on very bad connections... 871* Add extra debug messages to the alsa back end to diagnose strange DACs. 872* Add configuration file for the `libao` back end -- to change the buffer size and the latency offset, same as for stdout. 873* Add `shairport-sync.exe` to `.gitignore`. 874* Add a check to support compilation on a CYGWIN platform. 875* Add `rtptime` tags to metadata and picture information and add two new metadata items to precede and follow the transmission of a picture. Background: it seems that metadata and picture information for the same item, e.g. a track, are normally tagged with a timestamp called the `rtptime`; if they refer to the same item, they will have the same `rtptime` tags. The update here is to add the `rtptime` value, if available, as data to the `mdst` and `mden` metadata items, which are sent before ("MetaData STart") and after ("MetaData ENd") a metadata sequence. 876In addition, similar tags -- `pcst` ("PiCture STart") and `pcen` ("PiCture ENd") are now sent before and after a picture with the `rtptime` value, if available, sent as data. 877By the way, the progress metadata (`prgr` for "PRoGRess"), which is sent just when a track starts, contains the same `rtptime` as its middle element. 878 879 880Version 2.6 -- Stable Version 881---- 882This is basically version 2.4.2 with two small fixes. It's been bumped to 2.6 because (1) the new features added between 2.4.1 and 2.4.2 deserve more than just a bug-fix increment and (2) the development versions (2.5.x) should have lower numbers than the release versions, so that releases are always seen as upgrades. For example: 2.5.0.9 --> 2.6 looks like an upgrade, whereas 2.5.0.9 --> 2.4.2 looks like a downgrade. 883 884**Fixes** 885* For `systemd` users, the `shairport-sync.service` file is updated to point to the correct location of the shairport-sync application. 886* For Fedora users, the `shairport-sync.spec` file is updated to refer to 2.6. 887 888 889Version 2.4.2 890---- 891This release has important enhancements, bug fixes and documentation updates. It also appears to bring compatibility with Synology NAS devices. 892 893 894**New Features** 895* Source-specified Latencies. Shairport Sync now uses the latencies specified by the audio source. Background: the AirPlay protocol used by Shairport Sync allows the audio source to specify the exact delay or latency that should be applied to the audio stream. Until now, Shairport Sync ignored this information and used fixed preset latencies that were selected on the basis of the "User-Agent" setting. Using source-specified latencies means that Shairport Sync is able adapt automatically to different sources. 896Using source-specified latencies is now automatic unless non-standard static latencies have been specified in the configuration file or command line. Using non-standard latencies is usually done to compensate for delays in the back end of the system. For example, if the audio amplifier being driven by Shairport Sync has an inherent delay of its own -- as happens with many home theatre and surround sound systems -- then some users have reduced the latencies used by Shairport Sync to compensate. This usage is discouraged -- the `audio_backend_latency_offset` in the appropriate backend stanza (e.g. in the "alsa" stanza) should be used for this. Static latency settings are now deprecated, and will be removed in a future version of Shairport Sync. 897* Set Volume Range. This is a new setting that allows you to use just a portion of the full range of attenuation offered by a mixer. For example, if a mixer has a minimum volume of -80 dB and a maximum of +20 dB, you might wish to use only 60 dB of the 100 dB available. This might be because the sound becomes inaudible at the lowest setting and unbearably loud at the highest setting. It is for this reason that many domestic HiFi systems have a volume control range of only 60 to 80 dB. 898 Another possible reason to use this setting might be because the range specified by the mixer does not match the actual capabilities of the device. For example, the Raspberry Pi's DAC that feeds the built-in audio jack claims a range of 106 dB but has a useful range of only about 35dB. The new `volume_range_db` setting in the `general` stanza allows you to specify the maximum range from highest to lowest. The range suggested for the Raspberry Pi's built-in audio DAC, which feeds the headphone jack, is 35. Using it in this case gives the volume control a much more useful range of settings. 899 900**Bug fixes** 901* Sometimes, especially when using Shairport Sync as a system output, it would not play the audio stream. This was caused by an improperly initialised variable. Fixed. Synology NAS devices now seem to be working with Shairport Sync. 902* Fix in the `shairport.c`: the USE_CUSTOM_LOCAL_STATE_DIR macro was still being used when it should have been USE_CUSTOM_PID_DIR. 903* Fix a crashing bug -- if metadata was enabled but a pipename was not supplied, boom. 904 905**Other Changes** 906* Initial timing accuracy improved. The estimate of when to play the starting frame of the audio sequence has improved significantly. This leads to fewer corrections being needed at the start. 907* Volume ratios expressed in decibels are now consistently denominated in voltage decibels rather than power decibels. The rationale is that the levels refer to voltage levels, and power is proportional to the square of voltage. 908Thus a ratio of levels of 65535 to 1 is 96.3 dB rather than the 48.15 dB used before. 909* The latency figure returned to the source as part of the response to an rtsp request packet is 11,025, which may (?) be meant to indicate the minimum latency the device is capable of. 910* An experimental handler for a GET_PARAMETER rtsp request has been added. It does nothing except log the occurrence. 911* The RTSP request dispatcher now logs an event whenever an unrecognised rtsp has been made. 912 913 914Version 2.4.1 915---- 916This release has three small bug fixes and some small documentation updates. 917 918**Bug Fixes** 919 920Changes from the previous stable version -- 2.4 -- are summarised here: 921 * The USE_CUSTOM_LOCAL_STATE_DIR macro was still being used when it should have been USE_CUSTOM_PID_DIR. This could affect users using a custom location for the PID directory. 922 * A compiler error has been fixed that occurred if metadata was enabled and tinysvcmdns was included. 923 * A crash has been fixed that occurred if metadata was enabled and a metadata pipe name was not specified. 924(Thanks to the contributors who reported bugs.) 925 926**Small Changes** 927 * If a mixer being used to control volume does not have a control denominated in dB, a warning is logged and the mixer is not used. 928 * Slight revisions have been made to the configuration file `configure.ac` to make compilation on FreeBSD a little easier. 929 930Version 2.4 931---- 932**Stable release** 933 934This stable release is the culmination of the 2.3.X sequence of development releases. 935 936**Change Summary** 937 938Changes from the previous stable version -- 2.2.5 -- are summarised here: 939 * Settings are now read from a configuration file. Command-line settings are supported but discouraged. 940 * Metadata is now supported -- it can be delivered to a unix pipe for processing by a helper application. See https://github.com/mikebrady/shairport-sync-metadata-reader for a sample metadata reader. 941 * Raw PCM audio can be delivered to standard output ("stdout") or to a unix pipe. The internal architecture has changed considerably to support this. 942 * Support for compilation on OpenWrt back to Attitude Adjustment. 943 * Can play unencrypted audio streams -- complatible with, e.g. Whaale. 944 * Uses the libconfig library. 945 * Runs on a wider range of platforms, including Arch Linux and Fedora. 946 * Bug fixes. 947 948Please note that building instructions have changed slightly from the previous version. 949Also, the `-t hardware/software` option has been deprecated in the alsa back end. 950 951Version 2.3.13 952---- 953**Note** 954* We're getting ready to release the development branch as the new, stable, master branch at 2.4. If you're packaging Shairport Sync, you might prefer to wait a short while as we add a little polish before the release. 955 956**Changes** 957* Harmonise version numbers on the release and on the `shairport.spec` file used in Fedora. 958 959Version 2.3.12 960---- 961**Note** 962* We're getting ready to release the development branch as the new, stable, master branch at 2.4. If you're packaging Shairport Sync, you might prefer to wait a short while as we add a little polish before the release. 963 964**Changes** 965* `update-rc.d` has been removed from the installation script for System V because it causes problems for package makers. It's now noted in the user installation instructions. 966* The `alsa` group `mixer_type` setting is deprecated and you should stop using it. Its functionality has been subsumed into `mixer_name` – when you specify a `mixer_name` it automatically chooses the `hardware` mixer type. 967 968 969**Enhancements** 970* Larger range of interpolation. Shairport Sync was previously constrained not to make interpolations ("corrections") of more than about 1 per 1000 frames. This constraint has been relaxed, and it is now able to make corrections of up to 1 in 352 frames. This might result in a faster and undesirably sudden correction early during a play session, so a number of further changes have been made. The full set of these changes is as follows: 971 * No corrections happen for the first five seconds. 972 * Corrections of up to about 1 in 1000 for the next 25 seconds. 973 * Corrections of up to 1 in 352 thereafter. 974 975**Documentation Update** 976* Nearly there with updates concerning the configuration file. 977 978Version 2.3.11 979---- 980Documentation Update 981* Beginning to update the `man` document to include information about the configuration file. It's pretty sparse, but it's a start. 982 983Version 2.3.10 984---- 985Bug fix 986* The "pipe" backend used output code that would block if the pipe didn't have a reader. This has been replaced by non-blocking code. Here are some implications: 987 * When the pipe is created, Shairport Sync will not block if a reader isn't present. 988 * If the pipe doesn't have a reader when Shairport Sync wants to output to it, the output will be discarded. 989 * If a reader disappears while writing is occurring, the write will time out after five seconds. 990 * Shairport Sync will only close the pipe on termination. 991 992Version 2.3.9 993---- 994* Bug fix 995 * Specifying the configuration file using a *relative* file path now works properly. 996 * The debug verbosity requested with `-v`, `-vv`, etc. is now honoured before the configuration file is read. It is read and honoured from when the command line arguments are scanned the first time to get a possible configuration file path. 997 998Version 2.3.8 999---- 1000* Annoying changes you must make 1001 * You probably need to change your `./configure` arguments. The flag `with-initscript` has changed to `with-systemv`. It was previously enabled by default; now you must enable it explicitly. 1002 1003* Changes 1004 * Added limited support for installing into `systemd` and Fedora systems. For `systemd` support, use the configuration flag `--with-systemd` in place of `--with-systemv`. The installation does not do everything needed, such as defining special users and groups. 1005 * Renamed `with-initscript` configuration flag to `with-systemv` to describe its role more accurately. 1006 * A System V startup script is no longer installed by default; if you want it, ask for it with the `--with-systemv` configuration flag. 1007 * Added limited support for FreeBSD. You must specify `LDFLAGS='-I/usr/local/lib'` and `CPPFLAGS='-L/usr/local/include'` before running `./configure --with-foo etc.` 1008 * Removed the `-configfile` annotation from the version string because it's no longer optional; it's always there. 1009 * Removed the `dummy`, `pipe` and `stdout` backends from the standard build – they are now optional and are no longer automatically included in the build. 1010 1011* Bug fixes 1012 * Allow more stack space to prevent a segfault in certain configurations (thanks to https://github.com/joerg-krause). 1013 * Add missing header files(thanks to https://github.com/joerg-krause). 1014 * Removed some (hopefully) mostly silent bugs from the configure.ac file. 1015 1016Version 2.3.7 1017---- 1018* Changes 1019 * Removed the two different buffer lengths for the alsa back end that made a brief appearance in 2.3.5. 1020* Enhancements 1021 * Command line arguments are now given precedence over config file settings. This conforms to standard unix practice. 1022 * A `–without-pkg-config` configuration argument now allows for build systems, e.g. for older OpenWrt builds, that haven't fully implemented it. There is still some unhappiness in arch linux builds. 1023* More 1024 * Quite a bit of extra diagnostic code was written to investigate clock drift, DAC timings and so on. It was useful but has been commented out. If might be useful in the future. 1025 1026Version 2.3.5 1027---- 1028* Changes 1029 * The metadata item 'sndr' is no longer sent in metadata. It's been replaced by 'snam' and 'snua' -- see below. 1030* Enhancements 1031 * When a play session is initiated by a source, it attempts to reserve the player by sending an "ANNOUNCE" packet. Typically, a source device name and/or a source "user agent" is sent as part of the packet. The "user agent" is usually the name of the sending application along with some more information. If metadata is enabled, the source name, if provided, is emitted as a metadata item with the type `ssnc` and code `snam` and similarly the user agent, if provided, is sent with the type `ssnc` and code `snua`. 1032 * Two default buffer lengths for ALSA -- default 6615 frames if a software volume control is used, to minimise the response time to pause and volume control changes; default 22050 frames if a hardware volume control is used, to give more resilience to timing problems, sudden processor loading, etc. This is especially useful if you are processing metadata and artwork on the same machine. 1033 * Extra metadata: when a play session starts, the "Active-Remote" and "DACP-ID" fields -- information that can be used to identify the source -- are provided as metadata, with the type `ssnc` and the codes `acre` and `daid` respectively. The IDs are provided as strings. 1034 * Unencrypted audio data. The iOS player "Whaale" attempts to send unencrypted audio, presumably to save processing effort; if unsuccessful, it will send encrypted audio as normal. Shairport Sync now recognises and handles unencrypted audio data. (Apparently it always advertised that it could process unencrypted audio!) 1035 * Handle retransmitted audio in the control channel. When a packet of audio is missed, Shairport Sync will ask for it to be retransmitted. Normally the retransmitted audio comes back the audio channel, but "Whaale" sends it back in the control channel. (I think this is a bug in "Whaale".) Shairport Sync will now correctly handle retransmitted audio packets coming back in the control channel. 1036* Bugfixes 1037 * Generate properly-formed `<item>..</item>` items of information. 1038 1039Version 2.3.4 1040---- 1041* Enhancement 1042 * When a play session starts, Shairport Sync opens three UDP ports to communicate with the source. Until now, those ports could be any high numbered port. Now, they are located within a range of 100 port locations starting at port 6001. The starting port and the port range are settable by two new general settings in `/etc/shairport-sync.conf` -- `udp_port_base` (default 6001) and `udp_port_range` (default 100). To retain the previous behaviour, set the `udp_port_base` to `0`. 1043* Bugfixes 1044 * Fix an out-of-stack-space error that can occur in certain cases (thanks to https://github.com/joerg-krause). 1045 * Fix a couple of compiler warnings (thanks to https://github.com/joerg-krause). 1046 * Tidy up a couple of debug messages that were emitting misleading information. 1047 1048Version 2.3.3.2 1049---- 1050* Bugfix -- fixed an error in the sample configuration file. 1051 1052Version 2.3.3.1 1053---- 1054* Enhancement 1055 * Metadata format has changed slightly -- the format of each item is now `<item><type>..</type><code>..</code><length>..</length><data..>..</data></item>`, where the `<data..>..</data>` part is present if the length is non-zero. The change is that everything is now enclosed in an `<item>..</item>` pair. 1056 1057Version 2.3.2 and 2.3.3 1058---- 1059These releases were faulty and have been deleted. 1060 1061Version 2.3.1 1062----- 1063Some big changes "under the hood" have been made, leading to limited support for unsynchronised output to `stdout` or to a named pipe and continuation of defacto support for unsynchronised PulseAudio. Also, support for a configuration file in preference to command line options, an option to ignore volume control and other improvements are provided. 1064 1065In this release, Shairport Sync gains the ability to read settings from `/etc/shairport-sync.conf`. 1066This gives more flexibility in adding features gives better compatibility across different versions of Linux. 1067Existing command-line options continue to work, but some will be deprecated and may disappear in a future version of Shairport Sync. New settings will only be available via the configuration file. 1068 1069Note that, for the present, settings in the configuration will have priority over command line options for Shairport Sync itself, in contravention of the normal unix convention. Audio back end command line options, i.e. those after the `--`, have priority over configuration file settings for the audio backends. 1070 1071In moving to the the use of a configuration file, some "housekeeping" is being done -- some logical corrections and other small changes are being made to option names and modes of operations, so the settings in the configuration file do not exactly match command line options. 1072 1073When `make install` is executed, a sample configuration is installed or updated at `/etc/shairport-sync.conf.sample`. The same file is also installed as `/etc/shairport-sync.conf` if that file doesn't already exist. To prevent the configuration files being installed, use the configuration option `--without-configfiles`. 1074 1075* Pesky Change You Must Do Something About 1076 1077If you are using metadata, please note that the option has changed somewhat. The option `-M` has a new long name equivalent: `--metadata-pipename` and the argument you provide must now be the full name of the metadata pipe, e.g. `-M /tmp/shairport-sync-metadata`. 1078 1079* Enhancements 1080 * Shairport Sync now reads settings from the configuration file `/etc/shairport-sync.conf`. This has settings for most command-line options and it's where any new settings will go. A default configuration file will be installed if one doesn't exist, and a sample file configuration file is always installed or updated. Details of settings are provided in the sample file. Shairport Sync relies on the `libconfig` library to read configuration files. For the present, you can disable the new feature (and save the space taken up by `libconfig`) by using the configure option `--without-configfile-support`. 1081 * New command-line option `-c <file>` or `--configfile=<file>` allows you to specify a configuration file other than `/etc/shairport-sync.conf`. 1082 * Session Timeout and Allow Session Interruption can now be set independently. This is really some "housekeeping" as referred to above -- it's a kind of a bug fix, where the bug in question is an inappropriate connection of the setting of two parameters. To explain: (1) By default, when a source such as iTunes starts playing to the Shairport Sync device, any other source attempting to start a play session receives a "busy" signal. If a source disappears without warning, Shairport Sync will wait for 120 seconds before dropping the session and allowing another source to start a play session. (2) The command-line option `-t` or `--timeout` allows you to set the wait time before dropping the session. If you set this parameter to `0`, Shairport Sync will not send a "busy" signal, thus allowing another source to interrupt an existing one. (3) The problem is that if you set the parameter to `0`, a session will never be dropped if the source disappears without warning. 1083 The (obvious) fix for this is to separate the setting of the two parameters, and this is now done in the configuration file `/etc/shairport-sync.conf` -- please see the settings `allow_session_interruption` and `session_timeout`. The behaviour of the `-t` and `--timeout` command-line options is unchanged but deprecated. 1084 * New Option -- "Ignore Volume Control" ('ignore_volume_control'). If you set this to "yes", the output from Shairport Sync is always set at 100%. This is useful when you want to set the volume locally. Available via the settings file only. 1085 * Statistics option correctly reports when no frames are received in a sampling interval and when output is not being synchronised. 1086 * A new, supported audio back end called `stdout` provides raw 16-bit 44.1kHz stereo PCM output. To activate, set `output_backend = "stdout"` in the general section of the configuration file. Output is provided synchronously with the source feed. No stuffing or stripping is done. If you are feeding it to an output device that runs slower or faster, you'll eventually get buffer overflow or underflow in that device. To include support for this back end, use the configuration option `--with-stdout`. 1087 * Support for the `pipe` back end has been enhanced to provide raw 16-bit 44.1kHz stereo PCM output to a named pipe. To activate, set `output_backend = "pipe"` in the general section of the configuration and give the fully-specified pathname to the pipe in the pipe section of the configuration file -- see `etc/shairport-sync.conf.sample` for an example. No stuffing or stripping is done. If you are feeding it to an output device that runs slower or faster, you'll eventually get buffer overflow or underflow in that device. To include support for this back end, use the configuration option `--with-pipe`. 1088 * Support for the `dummy` audio backend device continues. To activate, set `output_backend = "dummy"` in in the general section of the configuration. To include support for this back end, use the configuration option `--with-dummy`. 1089 * Limited support for the PulseAudio audio backend continues. To activate, set `output_backend = "pulse"` in in the general section of the configuration. You must still enter its settings via the command line, after the `--` as before. Note that no stuffing or stripping is done: if the PulseAudio sink runs slower or faster, you'll eventually get buffer overflow or underflow. 1090 * New backend-specific settings are provided for setting the size of the backend's buffer and for adding or removing a fixed offset to the overall latency. The `audio_backend_buffer_desired_length` default is 6615 frames, or 0.15 seconds. On some slower machines, particularly with metadata processing going on, the DAC buffer can underflow on this setting, so it might be worth making the buffer larger. A problem on software mixers only is that changes to volume control settings have to propagate through the buffer to be heard, so the larger the buffer, the longer the response time. If you're using an alsa back end and are using a hardware mixers, this isn't a problem. The `audio_backend_latency_offset` allows you emit frames to the audio back end some time before or after the synchronised time. This would be useful, for example, if you are outputting to a device that takes 20 ms to process audio; yoou would specify a `audio_backend_latency_offset = -882`, where 882 is the number of frames in 20 ms, to compensate for the device delay. 1091 1092Version 2.3 1093----- 1094* Enhancements 1095 * Adding the System V startup script (the "initscript") is now a configuration option. The default is to include it, so if you want to omit the installation of the initscript, add the configuration option `--without-initscript`. 1096 * Metadata support is now a compile-time option: `--with-metadata`. 1097 * A metadata feed has been added. Use the option `-M <pipe-directory>`, e.g. `-M /tmp`. Shairport Sync will provide metadata in a pipe called `<pipe-directory>/shairport-sync-metadata`. (This is changed in 2.3.1.) There's a sample metadata reader at https://github.com/mikebrady/shairport-sync-metadata-reader. The format of the metadata is a mixture of XML-style tags, 4-character codes and base64 data. Please look at `rtsp.c` and `player.c` for examples. Please note that the format of the metadata may change. 1098Beware: there appears to be a serious bug in iTunes before 12.1.2, such that it may stall for a long period when sending large (more than a few hundred kilobytes) coverart images. 1099 1100* Bugfix 1101 * Fix a bug when compiling for Arch Linux on Raspberry Pi 2 (thanks to https://github.com/joaodriessen). 1102 * Fix a bug whereby if the ANNOUNCE and/or SETUP method fails, the play_lock mutex is never unlocked, thus blocking other clients from connecting. This can affect all types of users, but particularly Pulseaudio users. (Thanks to https://github.com/jclehner.) 1103 * Modify the init script to start after all services are ready. Add in a commented-out sleep command if users find it necessary (thanks to https://github.com/BNoiZe). 1104 * Two memory leaks fixed (thanks to https://github.com/pdgendt). 1105 * An error handling time specifications for flushes was causing an audible glitch when pausing and resuming some tracks. This has been fixed (thanks to https://github.com/Hamster128). 1106 1107Version 2.2.5 1108----- 1109* Bugfixes 1110 * Fix a segfault error that can occur in certain cases (thanks again to https://github.com/joerg-krause). 1111 * Include header files in common.c (thanks again to https://github.com/joerg-krause). 1112 1113Version 2.2.4 1114----- 1115* Bugfixes 1116 * Fix an out-of-stack-space error that can occur in certain cases (thanks to https://github.com/joerg-krause). 1117 * Fix a couple of compiler warnings (thanks to https://github.com/joerg-krause). 1118 1119Version 2.2.3 1120----- 1121* NOTE: all the metadata stuff has been moved to the "development" branch. This will become the stable branch henceforward, with just bug fixes or minor enhancements. Apologies for the inconvenience. 1122* Bugfixes 1123 * Fix a bug when compiling for Arch Linux on Raspberry Pi 2 (thanks to https://github.com/joaodriessen). 1124 * Fix a compiler warning (thanks to https://github.com/sdigit). 1125 1126Version 2.2.2 1127----- 1128* Enhancement 1129 * An extra latency setting for forked-daapd sources -- 99,400 frames, settable via a new option `--forkedDaapdLatency`. 1130 1131Version 2.2.1 1132----- 1133* Bugfixes: 1134 * If certain kinds of malformed RTSP packets were received, Shairport Sync would stop streaming. Now, it generally ignores faulty RTSP packets. 1135 * The `with-pulseaudio` compile option wasn't including a required library. This is fixed. Note that the PulseAudio back end doesn't work properly and is just included in the application because it was there in the original shairport. Play with it for experimentation only. 1136 * Fix typo in init.d script: "Headphones" -> "Headphone". 1137* Extra documentation 1138 * A brief note on how to compile `libsoxr` from source is included for the Raspberry Pi. 1139 1140Version 2.2 1141----- 1142* Enhancements: 1143 * New password option: `--password=SECRET` 1144 * New tolerance option: `--tolerance=FRAMES`. Use this option to specify the largest synchronisation error to allow before making corrections. The default is 88 frames, i.e. 2 milliseconds. The default tolerance is fine for streaming over wired ethernet; however, if some of the stream's path is via WiFi, or if the source is a third-party product, it may lead to much overcorrection -- i.e. the difference between "corrections" and "net correction" in the `--statistics` option. Increasing the tolerance may reduce the amount of overcorrection. 1145 1146Version 2.1.15 1147----- 1148* Changes to latency calculations: 1149 * The default latency is now 88,200 frames, exactly 2 seconds. It was 99,400 frames. As before, the `-L` option allows you to set the default latency. 1150 * The `-L` option is no longer deprecated. 1151 * The `-L` option no longer overrides the `-A` or `-i` options. 1152 * The default latency for iTunes is now 99,400 frames for iTunes 10 or later and 88,200 for earlier versions. 1153 * The `-i` or `--iTunesLatency` option only applies to iTunes 10 or later sources. 1154 1155Version 2.1.14 1156----- 1157* Documentation update: add information about the `-m` audio backend option. 1158The `-m` audio backend option allows you to specify the hardware mixer you are using. Not previously documented. 1159Functionality of shairport-sync is unchanged. 1160 1161Version 2.1.13 1162----- 1163* Compilation change: Begin to use PKG_CHECK_MODULES (in configure.ac) to statically link some of the libraries used by shairport-sync. It is intended to make it easier to build in the buildroot system. While sufficient for that purpose, note that PKG_CHECK_MODULES is not used for checking all the libraries yet. 1164Functionality of shairport-sync is unchanged. 1165 1166Version 2.1.12 1167----- 1168* Enhancement: `--statistics` 1169 Statistics are periodically written to the console (or the logfile) if this command-line option is included. They are no longer produced in verbose (`-v`) mode. 1170* Bugfixes for `tinysvcmdns` 1171 * A bug that prevented the device's IP number(s) and port numbers being advertised when using `tinysvcmdns` has been fixed. (Cause: name needed to have a `.local` suffix.) 1172 * Bugs causing the shairport service to semi-randomly disappear and reappear seem to be fixed. (Possible cause: incorrect timing settings when using `tinysvcmdns`.) 1173 1174Version 2.1.11 1175----- 1176* Enhancement 1177 * A man page is now installed -- do `man shairport-sync` or see it here: http://htmlpreview.github.io/?https://github.com/mikebrady/shairport-sync/blob/2.1/man/shairport-sync.html. 1178 1179Version 2.1.10 1180----- 1181* Bugfix 1182 * A bug that caused the `-t` timeout value to be incorrectly assigned has been fixed. (Cause: `config.timeout` defined as `int64_t` instead on `int`.) 1183 1184Version 2.1.9 1185----- 1186* Bugfixes 1187 * A bug that sometimes caused the initial volume setting to be ignored has been fixed. (Cause: setting volume before opening device.) 1188 * a bug that caused shairport-sync to become unresponsive or unavailable has been fixed. (Cause: draining rather than flushing the alsa device before stopping.) 1189 1190Version 2.1.8: 1191----- 1192* Enhancements 1193 * (This feature is intended to be useful to integrators.) Shairport Sync now the ability to immediately disconnect and reconnect to the sound output device while continuing to stream audio data from its client. 1194Send a `SIGUSR2` to the shairport-sync process to disconnect or send it a `SIGHUP` to reconnect. If shairport-sync has been started as a daemon using `shairport-sync -d`, then executing `shairport-sync -D` or `--disconnectFromOutput` will request the daemon to disconnect, and executing `shairport-sync -R` or `--reconnectToOutput` will request it to reconnect. 1195With this feature, you can allow Shairport Sync always to advertise and provide the streaming service, but still be able to disconnect it locally to enable other audio services to access the output device. 1196 1197* Annoying things you should know about if you're updating from a previous version: 1198 * Options `--with-openssl`, `--with-polarssl` have been replaced with a new option `--with-ssl=<option>` where `<option>` is either `openssl` or `polarssl`. 1199 * Option `--with-localstatedir` has been replaced with `--with-piddir`. This compilation option allows you to specify the directory in which the PID file will be written. The directory must exist and be writable. Supersedes the `--with-localstatedir` and describes the intended functionality a little more accurately. 1200 1201* Bugfixes 1202 * A small (?) bug in the flush logic has been corrected. Not causing any known problem. 1203 1204Version 2.1.5: 1205----- 1206* Enhancements 1207 * Adds a `--with-localstatedir` configuration option. When Shairport Sync is running as a daemon, it writes its Process ID (PID) to a file. The file must be stored in part of the file system that is writable. Most build systems choose an appropriate 'local state directory' for this automatically, but some -- notably `buildroot` -- don't always get it right for an embedded system. This compilation option allows you to specify the local state directory. Supersedes 2.1.4, which tried to do the same thing. 1208 1209Version 2.1.4: 1210----- 1211* Faulty -- withdrawn. 2.1.5 does it properly. 1212 1213 1214Version 2.1.3: 1215----- 1216* Stability Improvements 1217 * Fixed a bug which prevented Shairport Sync starting on an IPv4-only system. 1218 1219Version 2.1.2: 1220----- 1221* Stability Improvements 1222 * Improved buffering and flushing control, especially important on poor networks. 1223 1224 1225Version 2.1.1: 1226----- 1227* Enhancements 1228 * Add new -t or --timeout option. Normally, when playing audio from a source, the Shairport Sync device is unavailable to other devices requesting to play through it -- it returns a "busy" signal to those devices. If the audio source disappears without warning, the play session automatically terminates after a timeout period (default 120 seconds) and the device goes from being "busy" to being available for new play requests again. This option allows you to set that timeout period in seconds. 1229In addition, setting the timeout period to 0 means that play requests -- say from other devices on the network -- can interrupt and terminate the current session at any time. In other words, the "busy" feature of the device -- refusing connections from other players while playing from an existing source -- is turned off. 1230 * Allow -B and -E commands to have arguments, e.g. -B '/usr/bin/logger "Starting to play"' is now legitimate. 1231 1232* Annoying things you should know about if you're updating from 2.1: 1233 * Build now depends on the library libpopt -- see "Building and Installing" below. 1234 1235* Stability Improvements 1236 * Fixed a bug which would silence output after a few hours. 1237 * Tightened up management of packet buffers. 1238 * Improved estimate of lead-in silence to achieve initial synchronisation. 1239 1240Version 2.1: 1241----- 1242 1243* New features: 1244 1245 * Support for libsoxr, the SoX Resampler library -- see http://sourceforge.net/projects/soxr/. Briefly, Shairport Sync keeps in step with the audio source by deleting or inserting frames of audio into the stream as needed. This "interpolation" is normally inaudible, but it can be heard in some circumstances. Libsoxr allows this interpolation to be done much more smoothly and subtly. You can optionally include libsoxr support when building Shairport Sync. The big problem with libsoxr is that it is very compute intensive -- specifically floating point compute intensive -- and many embedded devices aren't powerful enough. Another issue is libsoxr is not yet in all linux distributions, so you might have to build it yourself. Available via the -S option. 1246 * Support for running (and optionally waiting for the completion of) programs before and after playing. See the -B, -E and -w options. 1247 * A new option to vary or turn off the resync threshold. See the -r option. 1248 * Version and build options. See the -V option. 1249 * Renamed program and init script. This is not exactly a big deal, but the name of the application itself and the default init script file have been renamed from "shairport" to "shairport-sync" to avoid confusion with other versions of shairport. 1250 * PolarSSL can be used in place of OpenSSL and friends. 1251 1252* Other stuff 1253 * Tinysvcmdns works as an alternative to, say, Avahi, but is now [really] dropped if you don't select it. Saves about 100k. 1254 * Lots of bug fixes. 1255 1256* Annoying things you should know about if you're updating from 2.0: 1257 * Compile options have changed -- see the Building and Installing section below. 1258 * The name of the program itself has changed from shairport to shairport-sync. You should remove the old version -- you can use `$which shairport` to locate it. 1259 * The name of the init script file has changed from shairport to shairport-sync. You should remove the old one. 1260 1261Version 2.0 1262---- 1263 1264* New features: 1265 * Audio synchronisation that works. The audio played by a Shairport Sync-powered device will stay in sync with the source. This allows you to synchronise Shairport Sync devices reliably with other devices playing the same source. For example, synchronised multi-room audio is possible without difficulty. 1266 * True mute and instant response to mute and volume control changes -- this requires hardware mixer support, available on most audio devices. Without hardware mixer support, response is also faster than before -- around 0.15 seconds. 1267 * Smoother volume control at the top and bottom of the range. 1268 * Another source can not interrupt an existing source playing via Shairport Sync. it will be given a 'busy' signal. 1269