1 /* 2 ** Copyright (C) 2002-2004 Erik de Castro Lopo <erikd@mega-nerd.com> 3 ** 4 ** This program is free software; you can redistribute it and/or modify 5 ** it under the terms of the GNU General Public License as published by 6 ** the Free Software Foundation; either version 2 of the License, or 7 ** (at your option) any later version. 8 ** 9 ** This program is distributed in the hope that it will be useful, 10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of 11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 ** GNU General Public License for more details. 13 ** 14 ** You should have received a copy of the GNU General Public License 15 ** along with this program; if not, write to the Free Software 16 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. 17 */ 18 19 /* 20 ** API documentation is available here: 21 ** http://www.mega-nerd.com/SRC/api.html 22 */ 23 24 #ifndef SAMPLERATE_H 25 #define SAMPLERATE_H 26 27 #ifdef __cplusplus 28 extern "C" { 29 #endif /* __cplusplus */ 30 31 /* Opaque data type SRC_STATE. */ 32 typedef struct SRC_STATE_tag SRC_STATE ; 33 34 /* SRC_DATA is used to pass data to src_simple() and src_process(). */ 35 typedef struct 36 { float *data_in, *data_out ; 37 38 long input_frames, output_frames ; 39 long input_frames_used, output_frames_gen ; 40 41 int end_of_input ; 42 43 double src_ratio ; 44 } SRC_DATA ; 45 46 /* SRC_CB_DATA is used with callback based API. */ 47 typedef struct 48 { long frames ; 49 float *data_in ; 50 } SRC_CB_DATA ; 51 52 /* 53 ** User supplied callback function type for use with src_callback_new() 54 ** and src_callback_read(). First parameter is the same pointer that was 55 ** passed into src_callback_new(). Second parameter is pointer to a 56 ** pointer. The user supplied callback function must modify *data to 57 ** point to the start of the user supplied float array. The user supplied 58 ** function must return the number of frames that **data points to. 59 */ 60 61 typedef long (*src_callback_t) (void *cb_data, float **data) ; 62 63 /* 64 ** Standard initialisation function : return an anonymous pointer to the 65 ** internal state of the converter. Choose a converter from the enums below. 66 ** Error returned in *error. 67 */ 68 69 SRC_STATE* src_new (int converter_type, int channels, int *error) ; 70 71 /* 72 ** Initilisation for callback based API : return an anonymous pointer to the 73 ** internal state of the converter. Choose a converter from the enums below. 74 ** The cb_data pointer can point to any data or be set to NULL. Whatever the 75 ** value, when processing, user supplied function "func" gets called with 76 ** cb_data as first parameter. 77 */ 78 79 SRC_STATE* src_callback_new (src_callback_t func, int converter_type, int channels, 80 int *error, void* cb_data) ; 81 82 /* 83 ** Cleanup all internal allocations. 84 ** Always returns NULL. 85 */ 86 87 SRC_STATE* src_delete (SRC_STATE *state) ; 88 89 /* 90 ** Standard processing function. 91 ** Returns non zero on error. 92 */ 93 94 int src_process (SRC_STATE *state, SRC_DATA *data) ; 95 96 /* 97 ** Callback based processing function. Read up to frames worth of data from 98 ** the converter int *data and return frames read or -1 on error. 99 */ 100 long src_callback_read (SRC_STATE *state, double src_ratio, long frames, float *data) ; 101 102 /* 103 ** Simple interface for performing a single conversion from input buffer to 104 ** output buffer at a fixed conversion ratio. 105 ** Simple interface does not require initialisation as it can only operate on 106 ** a single buffer worth of audio. 107 */ 108 109 int src_simple (SRC_DATA *data, int converter_type, int channels) ; 110 111 /* 112 ** This library contains a number of different sample rate converters, 113 ** numbered 0 through N. 114 ** 115 ** Return a string giving either a name or a more full description of each 116 ** sample rate converter or NULL if no sample rate converter exists for 117 ** the given value. The converters are sequentially numbered from 0 to N. 118 */ 119 120 const char *src_get_name (int converter_type) ; 121 const char *src_get_description (int converter_type) ; 122 const char *src_get_version (void) ; 123 124 /* 125 ** Set a new SRC ratio. This allows step responses 126 ** in the conversion ratio. 127 ** Returns non zero on error. 128 */ 129 130 int src_set_ratio (SRC_STATE *state, double new_ratio) ; 131 132 /* 133 ** Reset the internal SRC state. 134 ** Does not modify the quality settings. 135 ** Does not free any memory allocations. 136 ** Returns non zero on error. 137 */ 138 139 int src_reset (SRC_STATE *state) ; 140 141 /* 142 ** Return TRUE if ratio is a valid conversion ratio, FALSE 143 ** otherwise. 144 */ 145 146 int src_is_valid_ratio (double ratio) ; 147 148 /* 149 ** Return an error number. 150 */ 151 152 int src_error (SRC_STATE *state) ; 153 154 /* 155 ** Convert the error number into a string. 156 */ 157 const char* src_strerror (int error) ; 158 159 /* 160 ** The following enums can be used to set the interpolator type 161 ** using the function src_set_converter(). 162 */ 163 164 enum 165 { 166 SRC_SINC_BEST_QUALITY = 0, 167 SRC_SINC_MEDIUM_QUALITY = 1, 168 SRC_SINC_FASTEST = 2, 169 SRC_ZERO_ORDER_HOLD = 3, 170 SRC_LINEAR = 4 171 } ; 172 173 /* 174 ** Extra helper functions for converting from short to float and 175 ** back again. 176 */ 177 178 void src_short_to_float_array (const short *in, float *out, int len) ; 179 void src_float_to_short_array (const float *in, short *out, int len) ; 180 181 #ifdef __cplusplus 182 } /* extern "C" */ 183 #endif /* __cplusplus */ 184 185 #endif /* SAMPLERATE_H */ 186 187 /* 188 ** Do not edit or modify anything in this comment block. 189 ** The arch-tag line is a file identity tag for the GNU Arch 190 ** revision control system. 191 ** 192 ** arch-tag: 5421ef3e-c898-4ec3-8671-ea03d943ee00 193 */ 194