1 /********** 2 This library is free software; you can redistribute it and/or modify it under 3 the terms of the GNU Lesser General Public License as published by the 4 Free Software Foundation; either version 3 of the License, or (at your 5 option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.) 6 7 This library is distributed in the hope that it will be useful, but WITHOUT 8 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 9 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for 10 more details. 11 12 You should have received a copy of the GNU Lesser General Public License 13 along with this library; if not, write to the Free Software Foundation, Inc., 14 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 15 **********/ 16 // "liveMedia" 17 // Copyright (c) 1996-2020 Live Networks, Inc. All rights reserved. 18 // RTP sink for T.140 text (RFC 2793) 19 // C++ header 20 21 #ifndef _T140_TEXT_RTP_SINK_HH 22 #define _T140_TEXT_RTP_SINK_HH 23 24 #ifndef _TEXT_RTP_SINK_HH 25 #include "TextRTPSink.hh" 26 #endif 27 #ifndef _FRAMED_FILTER_HH 28 #include "FramedFilter.hh" 29 #endif 30 31 class T140IdleFilter; 32 33 class T140TextRTPSink: public TextRTPSink { 34 public: 35 static T140TextRTPSink* createNew(UsageEnvironment& env, Groupsock* RTPgs, unsigned char rtpPayloadFormat); 36 37 protected: 38 T140TextRTPSink(UsageEnvironment& env, Groupsock* RTPgs, unsigned char rtpPayloadFormat); 39 // called only by createNew() 40 41 virtual ~T140TextRTPSink(); 42 43 protected: // redefined virtual functions: 44 virtual Boolean continuePlaying(); 45 virtual void doSpecialFrameHandling(unsigned fragmentationOffset, 46 unsigned char* frameStart, 47 unsigned numBytesInFrame, 48 struct timeval framePresentationTime, 49 unsigned numRemainingBytes); 50 virtual Boolean frameCanAppearAfterPacketStart(unsigned char const* frameStart, 51 unsigned numBytesInFrame) const; 52 53 protected: 54 T140IdleFilter* fOurIdleFilter; 55 Boolean fAreInIdlePeriod; 56 }; 57 58 59 ////////// T140IdleFilter definition ////////// 60 61 // Because the T.140 text RTP payload format specification recommends that (empty) RTP packets be sent during 'idle periods' 62 // when no new text is available, we implement "T140TextRTPSink" using a separate "T140IdleFilter" class - sitting in front 63 // - that delivers, to the "T140TextRTPSink", a continuous sequence of (possibly) empty frames. 64 // (Note: This class should be used only by "T140TextRTPSink", or a subclass.) 65 66 class T140IdleFilter: public FramedFilter { 67 public: 68 T140IdleFilter(UsageEnvironment& env, FramedSource* inputSource); 69 virtual ~T140IdleFilter(); 70 71 private: // redefined virtual functions: 72 virtual void doGetNextFrame(); 73 virtual void doStopGettingFrames(); 74 75 private: 76 static void afterGettingFrame(void* clientData, unsigned frameSize, 77 unsigned numTruncatedBytes, 78 struct timeval presentationTime, 79 unsigned durationInMicroseconds); 80 void afterGettingFrame(unsigned frameSize, 81 unsigned numTruncatedBytes, 82 struct timeval presentationTime, 83 unsigned durationInMicroseconds); 84 85 static void handleIdleTimeout(void* clientData); 86 void handleIdleTimeout(); 87 88 void deliverFromBuffer(); 89 void deliverEmptyFrame(); 90 91 static void onSourceClosure(void* clientData); 92 void onSourceClosure(); 93 94 private: 95 TaskToken fIdleTimerTask; 96 unsigned fBufferSize, fNumBufferedBytes; 97 char* fBuffer; 98 unsigned fBufferedNumTruncatedBytes; // a count of truncated bytes from the upstream 99 struct timeval fBufferedDataPresentationTime; 100 unsigned fBufferedDataDurationInMicroseconds; 101 }; 102 103 #endif 104