1/* 2 * Copyright (C) 2011-2013 Michael Niedermayer (michaelni@gmx.at) 3 * 4 * This file is part of libswresample 5 * 6 * libswresample is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * libswresample is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with libswresample; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21#ifndef SWRESAMPLE_SWRESAMPLE_H 22#define SWRESAMPLE_SWRESAMPLE_H 23 24/** 25 * @file 26 * @ingroup lswr 27 * libswresample public header 28 */ 29 30/** 31 * @defgroup lswr Libswresample 32 * @{ 33 * 34 * Libswresample (lswr) is a library that handles audio resampling, sample 35 * format conversion and mixing. 36 * 37 * Interaction with lswr is done through SwrContext, which is 38 * allocated with swr_alloc() or swr_alloc_set_opts(). It is opaque, so all parameters 39 * must be set with the @ref avoptions API. 40 * 41 * The first thing you will need to do in order to use lswr is to allocate 42 * SwrContext. This can be done with swr_alloc() or swr_alloc_set_opts(). If you 43 * are using the former, you must set options through the @ref avoptions API. 44 * The latter function provides the same feature, but it allows you to set some 45 * common options in the same statement. 46 * 47 * For example the following code will setup conversion from planar float sample 48 * format to interleaved signed 16-bit integer, downsampling from 48kHz to 49 * 44.1kHz and downmixing from 5.1 channels to stereo (using the default mixing 50 * matrix). This is using the swr_alloc() function. 51 * @code 52 * SwrContext *swr = swr_alloc(); 53 * av_opt_set_channel_layout(swr, "in_channel_layout", AV_CH_LAYOUT_5POINT1, 0); 54 * av_opt_set_channel_layout(swr, "out_channel_layout", AV_CH_LAYOUT_STEREO, 0); 55 * av_opt_set_int(swr, "in_sample_rate", 48000, 0); 56 * av_opt_set_int(swr, "out_sample_rate", 44100, 0); 57 * av_opt_set_sample_fmt(swr, "in_sample_fmt", AV_SAMPLE_FMT_FLTP, 0); 58 * av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_S16, 0); 59 * @endcode 60 * 61 * The same job can be done using swr_alloc_set_opts() as well: 62 * @code 63 * SwrContext *swr = swr_alloc_set_opts(NULL, // we're allocating a new context 64 * AV_CH_LAYOUT_STEREO, // out_ch_layout 65 * AV_SAMPLE_FMT_S16, // out_sample_fmt 66 * 44100, // out_sample_rate 67 * AV_CH_LAYOUT_5POINT1, // in_ch_layout 68 * AV_SAMPLE_FMT_FLTP, // in_sample_fmt 69 * 48000, // in_sample_rate 70 * 0, // log_offset 71 * NULL); // log_ctx 72 * @endcode 73 * 74 * Once all values have been set, it must be initialized with swr_init(). If 75 * you need to change the conversion parameters, you can change the parameters 76 * using @ref AVOptions, as described above in the first example; or by using 77 * swr_alloc_set_opts(), but with the first argument the allocated context. 78 * You must then call swr_init() again. 79 * 80 * The conversion itself is done by repeatedly calling swr_convert(). 81 * Note that the samples may get buffered in swr if you provide insufficient 82 * output space or if sample rate conversion is done, which requires "future" 83 * samples. Samples that do not require future input can be retrieved at any 84 * time by using swr_convert() (in_count can be set to 0). 85 * At the end of conversion the resampling buffer can be flushed by calling 86 * swr_convert() with NULL in and 0 in_count. 87 * 88 * The samples used in the conversion process can be managed with the libavutil 89 * @ref lavu_sampmanip "samples manipulation" API, including av_samples_alloc() 90 * function used in the following example. 91 * 92 * The delay between input and output, can at any time be found by using 93 * swr_get_delay(). 94 * 95 * The following code demonstrates the conversion loop assuming the parameters 96 * from above and caller-defined functions get_input() and handle_output(): 97 * @code 98 * uint8_t **input; 99 * int in_samples; 100 * 101 * while (get_input(&input, &in_samples)) { 102 * uint8_t *output; 103 * int out_samples = av_rescale_rnd(swr_get_delay(swr, 48000) + 104 * in_samples, 44100, 48000, AV_ROUND_UP); 105 * av_samples_alloc(&output, NULL, 2, out_samples, 106 * AV_SAMPLE_FMT_S16, 0); 107 * out_samples = swr_convert(swr, &output, out_samples, 108 * input, in_samples); 109 * handle_output(output, out_samples); 110 * av_freep(&output); 111 * } 112 * @endcode 113 * 114 * When the conversion is finished, the conversion 115 * context and everything associated with it must be freed with swr_free(). 116 * A swr_close() function is also available, but it exists mainly for 117 * compatibility with libavresample, and is not required to be called. 118 * 119 * There will be no memory leak if the data is not completely flushed before 120 * swr_free(). 121 */ 122 123#include <stdint.h> 124#include "libavutil/samplefmt.h" 125 126#include "libswresample/version.h" 127 128#if LIBSWRESAMPLE_VERSION_MAJOR < 1 129#define SWR_CH_MAX 32 ///< Maximum number of channels 130#endif 131 132/** 133 * @name Option constants 134 * These constants are used for the @ref avoptions interface for lswr. 135 * @{ 136 * 137 */ 138 139#define SWR_FLAG_RESAMPLE 1 ///< Force resampling even if equal sample rate 140//TODO use int resample ? 141//long term TODO can we enable this dynamically? 142 143/** Dithering algorithms */ 144enum SwrDitherType { 145 SWR_DITHER_NONE = 0, 146 SWR_DITHER_RECTANGULAR, 147 SWR_DITHER_TRIANGULAR, 148 SWR_DITHER_TRIANGULAR_HIGHPASS, 149 150 SWR_DITHER_NS = 64, ///< not part of API/ABI 151 SWR_DITHER_NS_LIPSHITZ, 152 SWR_DITHER_NS_F_WEIGHTED, 153 SWR_DITHER_NS_MODIFIED_E_WEIGHTED, 154 SWR_DITHER_NS_IMPROVED_E_WEIGHTED, 155 SWR_DITHER_NS_SHIBATA, 156 SWR_DITHER_NS_LOW_SHIBATA, 157 SWR_DITHER_NS_HIGH_SHIBATA, 158 SWR_DITHER_NB, ///< not part of API/ABI 159}; 160 161/** Resampling Engines */ 162enum SwrEngine { 163 SWR_ENGINE_SWR, /**< SW Resampler */ 164 SWR_ENGINE_SOXR, /**< SoX Resampler */ 165 SWR_ENGINE_NB, ///< not part of API/ABI 166}; 167 168/** Resampling Filter Types */ 169enum SwrFilterType { 170 SWR_FILTER_TYPE_CUBIC, /**< Cubic */ 171 SWR_FILTER_TYPE_BLACKMAN_NUTTALL, /**< Blackman Nuttall Windowed Sinc */ 172 SWR_FILTER_TYPE_KAISER, /**< Kaiser Windowed Sinc */ 173}; 174 175/** 176 * @} 177 */ 178 179/** 180 * The libswresample context. Unlike libavcodec and libavformat, this structure 181 * is opaque. This means that if you would like to set options, you must use 182 * the @ref avoptions API and cannot directly set values to members of the 183 * structure. 184 */ 185typedef struct SwrContext SwrContext; 186 187/** 188 * Get the AVClass for SwrContext. It can be used in combination with 189 * AV_OPT_SEARCH_FAKE_OBJ for examining options. 190 * 191 * @see av_opt_find(). 192 * @return the AVClass of SwrContext 193 */ 194const AVClass *swr_get_class(void); 195 196/** 197 * @name SwrContext constructor functions 198 * @{ 199 */ 200 201/** 202 * Allocate SwrContext. 203 * 204 * If you use this function you will need to set the parameters (manually or 205 * with swr_alloc_set_opts()) before calling swr_init(). 206 * 207 * @see swr_alloc_set_opts(), swr_init(), swr_free() 208 * @return NULL on error, allocated context otherwise 209 */ 210struct SwrContext *swr_alloc(void); 211 212/** 213 * Initialize context after user parameters have been set. 214 * 215 * @param[in,out] s Swr context to initialize 216 * @return AVERROR error code in case of failure. 217 */ 218int swr_init(struct SwrContext *s); 219 220/** 221 * Check whether an swr context has been initialized or not. 222 * 223 * @param[in] s Swr context to check 224 * @see swr_init() 225 * @return positive if it has been initialized, 0 if not initialized 226 */ 227int swr_is_initialized(struct SwrContext *s); 228 229/** 230 * Allocate SwrContext if needed and set/reset common parameters. 231 * 232 * This function does not require s to be allocated with swr_alloc(). On the 233 * other hand, swr_alloc() can use swr_alloc_set_opts() to set the parameters 234 * on the allocated context. 235 * 236 * @param s existing Swr context if available, or NULL if not 237 * @param out_ch_layout output channel layout (AV_CH_LAYOUT_*) 238 * @param out_sample_fmt output sample format (AV_SAMPLE_FMT_*). 239 * @param out_sample_rate output sample rate (frequency in Hz) 240 * @param in_ch_layout input channel layout (AV_CH_LAYOUT_*) 241 * @param in_sample_fmt input sample format (AV_SAMPLE_FMT_*). 242 * @param in_sample_rate input sample rate (frequency in Hz) 243 * @param log_offset logging level offset 244 * @param log_ctx parent logging context, can be NULL 245 * 246 * @see swr_init(), swr_free() 247 * @return NULL on error, allocated context otherwise 248 */ 249struct SwrContext *swr_alloc_set_opts(struct SwrContext *s, 250 int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate, 251 int64_t in_ch_layout, enum AVSampleFormat in_sample_fmt, int in_sample_rate, 252 int log_offset, void *log_ctx); 253 254/** 255 * @} 256 * 257 * @name SwrContext destructor functions 258 * @{ 259 */ 260 261/** 262 * Free the given SwrContext and set the pointer to NULL. 263 * 264 * @param[in] s a pointer to a pointer to Swr context 265 */ 266void swr_free(struct SwrContext **s); 267 268/** 269 * Closes the context so that swr_is_initialized() returns 0. 270 * 271 * The context can be brought back to life by running swr_init(), 272 * swr_init() can also be used without swr_close(). 273 * This function is mainly provided for simplifying the usecase 274 * where one tries to support libavresample and libswresample. 275 * 276 * @param[in,out] s Swr context to be closed 277 */ 278void swr_close(struct SwrContext *s); 279 280/** 281 * @} 282 * 283 * @name Core conversion functions 284 * @{ 285 */ 286 287/** Convert audio. 288 * 289 * in and in_count can be set to 0 to flush the last few samples out at the 290 * end. 291 * 292 * If more input is provided than output space then the input will be buffered. 293 * You can avoid this buffering by providing more output space than input. 294 * Conversion will run directly without copying whenever possible. 295 * 296 * @param s allocated Swr context, with parameters set 297 * @param out output buffers, only the first one need be set in case of packed audio 298 * @param out_count amount of space available for output in samples per channel 299 * @param in input buffers, only the first one need to be set in case of packed audio 300 * @param in_count number of input samples available in one channel 301 * 302 * @return number of samples output per channel, negative value on error 303 */ 304int swr_convert(struct SwrContext *s, uint8_t **out, int out_count, 305 const uint8_t **in , int in_count); 306 307/** 308 * Convert the next timestamp from input to output 309 * timestamps are in 1/(in_sample_rate * out_sample_rate) units. 310 * 311 * @note There are 2 slightly differently behaving modes. 312 * @li When automatic timestamp compensation is not used, (min_compensation >= FLT_MAX) 313 * in this case timestamps will be passed through with delays compensated 314 * @li When automatic timestamp compensation is used, (min_compensation < FLT_MAX) 315 * in this case the output timestamps will match output sample numbers. 316 * See ffmpeg-resampler(1) for the two modes of compensation. 317 * 318 * @param s[in] initialized Swr context 319 * @param pts[in] timestamp for the next input sample, INT64_MIN if unknown 320 * @see swr_set_compensation(), swr_drop_output(), and swr_inject_silence() are 321 * function used internally for timestamp compensation. 322 * @return the output timestamp for the next output sample 323 */ 324int64_t swr_next_pts(struct SwrContext *s, int64_t pts); 325 326/** 327 * @} 328 * 329 * @name Low-level option setting functions 330 * These functons provide a means to set low-level options that is not possible 331 * with the AVOption API. 332 * @{ 333 */ 334 335/** 336 * Activate resampling compensation ("soft" compensation). This function is 337 * internally called when needed in swr_next_pts(). 338 * 339 * @param[in,out] s allocated Swr context. If it is not initialized, 340 * or SWR_FLAG_RESAMPLE is not set, swr_init() is 341 * called with the flag set. 342 * @param[in] sample_delta delta in PTS per sample 343 * @param[in] compensation_distance number of samples to compensate for 344 * @return >= 0 on success, AVERROR error codes if: 345 * @li @c s is NULL, 346 * @li @c compensation_distance is less than 0, 347 * @li @c compensation_distance is 0 but sample_delta is not, 348 * @li compensation unsupported by resampler, or 349 * @li swr_init() fails when called. 350 */ 351int swr_set_compensation(struct SwrContext *s, int sample_delta, int compensation_distance); 352 353/** 354 * Set a customized input channel mapping. 355 * 356 * @param[in,out] s allocated Swr context, not yet initialized 357 * @param[in] channel_map customized input channel mapping (array of channel 358 * indexes, -1 for a muted channel) 359 * @return >= 0 on success, or AVERROR error code in case of failure. 360 */ 361int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map); 362 363/** 364 * Set a customized remix matrix. 365 * 366 * @param s allocated Swr context, not yet initialized 367 * @param matrix remix coefficients; matrix[i + stride * o] is 368 * the weight of input channel i in output channel o 369 * @param stride offset between lines of the matrix 370 * @return >= 0 on success, or AVERROR error code in case of failure. 371 */ 372int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride); 373 374/** 375 * @} 376 * 377 * @name Sample handling functions 378 * @{ 379 */ 380 381/** 382 * Drops the specified number of output samples. 383 * 384 * This function, along with swr_inject_silence(), is called by swr_next_pts() 385 * if needed for "hard" compensation. 386 * 387 * @param s allocated Swr context 388 * @param count number of samples to be dropped 389 * 390 * @return >= 0 on success, or a negative AVERROR code on failure 391 */ 392int swr_drop_output(struct SwrContext *s, int count); 393 394/** 395 * Injects the specified number of silence samples. 396 * 397 * This function, along with swr_drop_output(), is called by swr_next_pts() 398 * if needed for "hard" compensation. 399 * 400 * @param s allocated Swr context 401 * @param count number of samples to be dropped 402 * 403 * @return >= 0 on success, or a negative AVERROR code on failure 404 */ 405int swr_inject_silence(struct SwrContext *s, int count); 406 407/** 408 * Gets the delay the next input sample will experience relative to the next output sample. 409 * 410 * Swresample can buffer data if more input has been provided than available 411 * output space, also converting between sample rates needs a delay. 412 * This function returns the sum of all such delays. 413 * The exact delay is not necessarily an integer value in either input or 414 * output sample rate. Especially when downsampling by a large value, the 415 * output sample rate may be a poor choice to represent the delay, similarly 416 * for upsampling and the input sample rate. 417 * 418 * @param s swr context 419 * @param base timebase in which the returned delay will be: 420 * @li if it's set to 1 the returned delay is in seconds 421 * @li if it's set to 1000 the returned delay is in milliseconds 422 * @li if it's set to the input sample rate then the returned 423 * delay is in input samples 424 * @li if it's set to the output sample rate then the returned 425 * delay is in output samples 426 * @li if it's the least common multiple of in_sample_rate and 427 * out_sample_rate then an exact rounding-free delay will be 428 * returned 429 * @returns the delay in 1 / @c base units. 430 */ 431int64_t swr_get_delay(struct SwrContext *s, int64_t base); 432 433/** 434 * @} 435 * 436 * @name Configuration accessors 437 * @{ 438 */ 439 440/** 441 * Return the @ref LIBSWRESAMPLE_VERSION_INT constant. 442 * 443 * This is useful to check if the build-time libswresample has the same version 444 * as the run-time one. 445 * 446 * @returns the unsigned int-typed version 447 */ 448unsigned swresample_version(void); 449 450/** 451 * Return the swr build-time configuration. 452 * 453 * @returns the build-time @c ./configure flags 454 */ 455const char *swresample_configuration(void); 456 457/** 458 * Return the swr license. 459 * 460 * @returns the license of libswresample, determined at build-time 461 */ 462const char *swresample_license(void); 463 464/** 465 * @} 466 * @} 467 */ 468 469#endif /* SWRESAMPLE_SWRESAMPLE_H */ 470