swresample.h (22340B)
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 * Audio resampling, sample format conversion and mixing library. 35 * 36 * Interaction with lswr is done through SwrContext, which is 37 * allocated with swr_alloc() or swr_alloc_set_opts2(). It is opaque, so all parameters 38 * must be set with the @ref avoptions API. 39 * 40 * The first thing you will need to do in order to use lswr is to allocate 41 * SwrContext. This can be done with swr_alloc() or swr_alloc_set_opts2(). If you 42 * are using the former, you must set options through the @ref avoptions API. 43 * The latter function provides the same feature, but it allows you to set some 44 * common options in the same statement. 45 * 46 * For example the following code will setup conversion from planar float sample 47 * format to interleaved signed 16-bit integer, downsampling from 48kHz to 48 * 44.1kHz and downmixing from 5.1 channels to stereo (using the default mixing 49 * matrix). This is using the swr_alloc() function. 50 * @code 51 * SwrContext *swr = swr_alloc(); 52 * av_opt_set_channel_layout(swr, "in_channel_layout", AV_CH_LAYOUT_5POINT1, 0); 53 * av_opt_set_channel_layout(swr, "out_channel_layout", AV_CH_LAYOUT_STEREO, 0); 54 * av_opt_set_int(swr, "in_sample_rate", 48000, 0); 55 * av_opt_set_int(swr, "out_sample_rate", 44100, 0); 56 * av_opt_set_sample_fmt(swr, "in_sample_fmt", AV_SAMPLE_FMT_FLTP, 0); 57 * av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_S16, 0); 58 * @endcode 59 * 60 * The same job can be done using swr_alloc_set_opts2() as well: 61 * @code 62 * SwrContext *swr = NULL; 63 * int ret = swr_alloc_set_opts2(&swr, // we're allocating a new context 64 * &(AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO, // out_ch_layout 65 * AV_SAMPLE_FMT_S16, // out_sample_fmt 66 * 44100, // out_sample_rate 67 * &(AVChannelLayout)AV_CHANNEL_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_opts2(), 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/channel_layout.h" 125 #include "libavutil/frame.h" 126 #include "libavutil/samplefmt.h" 127 128 #include "libswresample/version_major.h" 129 #ifndef HAVE_AV_CONFIG_H 130 /* When included as part of the ffmpeg build, only include the major version 131 * to avoid unnecessary rebuilds. When included externally, keep including 132 * the full version information. */ 133 #include "libswresample/version.h" 134 #endif 135 136 /** 137 * @name Option constants 138 * These constants are used for the @ref avoptions interface for lswr. 139 * @{ 140 * 141 */ 142 143 #define SWR_FLAG_RESAMPLE 1 ///< Force resampling even if equal sample rate 144 //TODO use int resample ? 145 //long term TODO can we enable this dynamically? 146 147 /** Dithering algorithms */ 148 enum SwrDitherType { 149 SWR_DITHER_NONE = 0, 150 SWR_DITHER_RECTANGULAR, 151 SWR_DITHER_TRIANGULAR, 152 SWR_DITHER_TRIANGULAR_HIGHPASS, 153 154 SWR_DITHER_NS = 64, ///< not part of API/ABI 155 SWR_DITHER_NS_LIPSHITZ, 156 SWR_DITHER_NS_F_WEIGHTED, 157 SWR_DITHER_NS_MODIFIED_E_WEIGHTED, 158 SWR_DITHER_NS_IMPROVED_E_WEIGHTED, 159 SWR_DITHER_NS_SHIBATA, 160 SWR_DITHER_NS_LOW_SHIBATA, 161 SWR_DITHER_NS_HIGH_SHIBATA, 162 SWR_DITHER_NB, ///< not part of API/ABI 163 }; 164 165 /** Resampling Engines */ 166 enum SwrEngine { 167 SWR_ENGINE_SWR, /**< SW Resampler */ 168 SWR_ENGINE_SOXR, /**< SoX Resampler */ 169 SWR_ENGINE_NB, ///< not part of API/ABI 170 }; 171 172 /** Resampling Filter Types */ 173 enum SwrFilterType { 174 SWR_FILTER_TYPE_CUBIC, /**< Cubic */ 175 SWR_FILTER_TYPE_BLACKMAN_NUTTALL, /**< Blackman Nuttall windowed sinc */ 176 SWR_FILTER_TYPE_KAISER, /**< Kaiser windowed sinc */ 177 }; 178 179 /** 180 * @} 181 */ 182 183 /** 184 * The libswresample context. Unlike libavcodec and libavformat, this structure 185 * is opaque. This means that if you would like to set options, you must use 186 * the @ref avoptions API and cannot directly set values to members of the 187 * structure. 188 */ 189 typedef struct SwrContext SwrContext; 190 191 /** 192 * Get the AVClass for SwrContext. It can be used in combination with 193 * AV_OPT_SEARCH_FAKE_OBJ for examining options. 194 * 195 * @see av_opt_find(). 196 * @return the AVClass of SwrContext 197 */ 198 const AVClass *swr_get_class(void); 199 200 /** 201 * @name SwrContext constructor functions 202 * @{ 203 */ 204 205 /** 206 * Allocate SwrContext. 207 * 208 * If you use this function you will need to set the parameters (manually or 209 * with swr_alloc_set_opts2()) before calling swr_init(). 210 * 211 * @see swr_alloc_set_opts2(), swr_init(), swr_free() 212 * @return NULL on error, allocated context otherwise 213 */ 214 struct SwrContext *swr_alloc(void); 215 216 /** 217 * Initialize context after user parameters have been set. 218 * @note The context must be configured using the AVOption API. 219 * 220 * @see av_opt_set_int() 221 * @see av_opt_set_dict() 222 * 223 * @param[in,out] s Swr context to initialize 224 * @return AVERROR error code in case of failure. 225 */ 226 int swr_init(struct SwrContext *s); 227 228 /** 229 * Check whether an swr context has been initialized or not. 230 * 231 * @param[in] s Swr context to check 232 * @see swr_init() 233 * @return positive if it has been initialized, 0 if not initialized 234 */ 235 int swr_is_initialized(struct SwrContext *s); 236 237 /** 238 * Allocate SwrContext if needed and set/reset common parameters. 239 * 240 * This function does not require *ps to be allocated with swr_alloc(). On the 241 * other hand, swr_alloc() can use swr_alloc_set_opts2() to set the parameters 242 * on the allocated context. 243 * 244 * @param ps Pointer to an existing Swr context if available, or to NULL if not. 245 * On success, *ps will be set to the allocated context. 246 * @param out_ch_layout output channel layout (e.g. AV_CHANNEL_LAYOUT_*) 247 * @param out_sample_fmt output sample format (AV_SAMPLE_FMT_*). 248 * @param out_sample_rate output sample rate (frequency in Hz) 249 * @param in_ch_layout input channel layout (e.g. AV_CHANNEL_LAYOUT_*) 250 * @param in_sample_fmt input sample format (AV_SAMPLE_FMT_*). 251 * @param in_sample_rate input sample rate (frequency in Hz) 252 * @param log_offset logging level offset 253 * @param log_ctx parent logging context, can be NULL 254 * 255 * @see swr_init(), swr_free() 256 * @return 0 on success, a negative AVERROR code on error. 257 * On error, the Swr context is freed and *ps set to NULL. 258 */ 259 int swr_alloc_set_opts2(struct SwrContext **ps, 260 const AVChannelLayout *out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate, 261 const AVChannelLayout *in_ch_layout, enum AVSampleFormat in_sample_fmt, int in_sample_rate, 262 int log_offset, void *log_ctx); 263 /** 264 * @} 265 * 266 * @name SwrContext destructor functions 267 * @{ 268 */ 269 270 /** 271 * Free the given SwrContext and set the pointer to NULL. 272 * 273 * @param[in] s a pointer to a pointer to Swr context 274 */ 275 void swr_free(struct SwrContext **s); 276 277 /** 278 * Closes the context so that swr_is_initialized() returns 0. 279 * 280 * The context can be brought back to life by running swr_init(), 281 * swr_init() can also be used without swr_close(). 282 * This function is mainly provided for simplifying the usecase 283 * where one tries to support libavresample and libswresample. 284 * 285 * @param[in,out] s Swr context to be closed 286 */ 287 void swr_close(struct SwrContext *s); 288 289 /** 290 * @} 291 * 292 * @name Core conversion functions 293 * @{ 294 */ 295 296 /** Convert audio. 297 * 298 * in and in_count can be set to 0 to flush the last few samples out at the 299 * end. 300 * 301 * If more input is provided than output space, then the input will be buffered. 302 * You can avoid this buffering by using swr_get_out_samples() to retrieve an 303 * upper bound on the required number of output samples for the given number of 304 * input samples. Conversion will run directly without copying whenever possible. 305 * 306 * @param s allocated Swr context, with parameters set 307 * @param out output buffers, only the first one need be set in case of packed audio 308 * @param out_count amount of space available for output in samples per channel 309 * @param in input buffers, only the first one need to be set in case of packed audio 310 * @param in_count number of input samples available in one channel 311 * 312 * @return number of samples output per channel, negative value on error 313 */ 314 int swr_convert(struct SwrContext *s, uint8_t * const *out, int out_count, 315 const uint8_t * const *in , int in_count); 316 317 /** 318 * Convert the next timestamp from input to output 319 * timestamps are in 1/(in_sample_rate * out_sample_rate) units. 320 * 321 * @note There are 2 slightly differently behaving modes. 322 * @li When automatic timestamp compensation is not used, (min_compensation >= FLT_MAX) 323 * in this case timestamps will be passed through with delays compensated 324 * @li When automatic timestamp compensation is used, (min_compensation < FLT_MAX) 325 * in this case the output timestamps will match output sample numbers. 326 * See ffmpeg-resampler(1) for the two modes of compensation. 327 * 328 * @param[in] s initialized Swr context 329 * @param[in] pts timestamp for the next input sample, INT64_MIN if unknown 330 * @see swr_set_compensation(), swr_drop_output(), and swr_inject_silence() are 331 * function used internally for timestamp compensation. 332 * @return the output timestamp for the next output sample 333 */ 334 int64_t swr_next_pts(struct SwrContext *s, int64_t pts); 335 336 /** 337 * @} 338 * 339 * @name Low-level option setting functions 340 * These functons provide a means to set low-level options that is not possible 341 * with the AVOption API. 342 * @{ 343 */ 344 345 /** 346 * Activate resampling compensation ("soft" compensation). This function is 347 * internally called when needed in swr_next_pts(). 348 * 349 * @param[in,out] s allocated Swr context. If it is not initialized, 350 * or SWR_FLAG_RESAMPLE is not set, swr_init() is 351 * called with the flag set. 352 * @param[in] sample_delta delta in PTS per sample 353 * @param[in] compensation_distance number of samples to compensate for 354 * @return >= 0 on success, AVERROR error codes if: 355 * @li @c s is NULL, 356 * @li @c compensation_distance is less than 0, 357 * @li @c compensation_distance is 0 but sample_delta is not, 358 * @li compensation unsupported by resampler, or 359 * @li swr_init() fails when called. 360 */ 361 int swr_set_compensation(struct SwrContext *s, int sample_delta, int compensation_distance); 362 363 /** 364 * Set a customized input channel mapping. 365 * 366 * @param[in,out] s allocated Swr context, not yet initialized 367 * @param[in] channel_map customized input channel mapping (array of channel 368 * indexes, -1 for a muted channel) 369 * @return >= 0 on success, or AVERROR error code in case of failure. 370 */ 371 int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map); 372 373 /** 374 * Generate a channel mixing matrix. 375 * 376 * This function is the one used internally by libswresample for building the 377 * default mixing matrix. It is made public just as a utility function for 378 * building custom matrices. 379 * 380 * @param in_layout input channel layout 381 * @param out_layout output channel layout 382 * @param center_mix_level mix level for the center channel 383 * @param surround_mix_level mix level for the surround channel(s) 384 * @param lfe_mix_level mix level for the low-frequency effects channel 385 * @param rematrix_maxval if 1.0, coefficients will be normalized to prevent 386 * overflow. if INT_MAX, coefficients will not be 387 * normalized. 388 * @param[out] matrix mixing coefficients; matrix[i + stride * o] is 389 * the weight of input channel i in output channel o. 390 * @param stride distance between adjacent input channels in the 391 * matrix array 392 * @param matrix_encoding matrixed stereo downmix mode (e.g. dplii) 393 * @param log_ctx parent logging context, can be NULL 394 * @return 0 on success, negative AVERROR code on failure 395 */ 396 int swr_build_matrix2(const AVChannelLayout *in_layout, const AVChannelLayout *out_layout, 397 double center_mix_level, double surround_mix_level, 398 double lfe_mix_level, double maxval, 399 double rematrix_volume, double *matrix, 400 ptrdiff_t stride, enum AVMatrixEncoding matrix_encoding, 401 void *log_context); 402 403 /** 404 * Set a customized remix matrix. 405 * 406 * @param s allocated Swr context, not yet initialized 407 * @param matrix remix coefficients; matrix[i + stride * o] is 408 * the weight of input channel i in output channel o 409 * @param stride offset between lines of the matrix 410 * @return >= 0 on success, or AVERROR error code in case of failure. 411 */ 412 int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride); 413 414 /** 415 * @} 416 * 417 * @name Sample handling functions 418 * @{ 419 */ 420 421 /** 422 * Drops the specified number of output samples. 423 * 424 * This function, along with swr_inject_silence(), is called by swr_next_pts() 425 * if needed for "hard" compensation. 426 * 427 * @param s allocated Swr context 428 * @param count number of samples to be dropped 429 * 430 * @return >= 0 on success, or a negative AVERROR code on failure 431 */ 432 int swr_drop_output(struct SwrContext *s, int count); 433 434 /** 435 * Injects the specified number of silence samples. 436 * 437 * This function, along with swr_drop_output(), is called by swr_next_pts() 438 * if needed for "hard" compensation. 439 * 440 * @param s allocated Swr context 441 * @param count number of samples to be dropped 442 * 443 * @return >= 0 on success, or a negative AVERROR code on failure 444 */ 445 int swr_inject_silence(struct SwrContext *s, int count); 446 447 /** 448 * Gets the delay the next input sample will experience relative to the next output sample. 449 * 450 * Swresample can buffer data if more input has been provided than available 451 * output space, also converting between sample rates needs a delay. 452 * This function returns the sum of all such delays. 453 * The exact delay is not necessarily an integer value in either input or 454 * output sample rate. Especially when downsampling by a large value, the 455 * output sample rate may be a poor choice to represent the delay, similarly 456 * for upsampling and the input sample rate. 457 * 458 * @param s swr context 459 * @param base timebase in which the returned delay will be: 460 * @li if it's set to 1 the returned delay is in seconds 461 * @li if it's set to 1000 the returned delay is in milliseconds 462 * @li if it's set to the input sample rate then the returned 463 * delay is in input samples 464 * @li if it's set to the output sample rate then the returned 465 * delay is in output samples 466 * @li if it's the least common multiple of in_sample_rate and 467 * out_sample_rate then an exact rounding-free delay will be 468 * returned 469 * @returns the delay in 1 / @c base units. 470 */ 471 int64_t swr_get_delay(struct SwrContext *s, int64_t base); 472 473 /** 474 * Find an upper bound on the number of samples that the next swr_convert 475 * call will output, if called with in_samples of input samples. This 476 * depends on the internal state, and anything changing the internal state 477 * (like further swr_convert() calls) will may change the number of samples 478 * swr_get_out_samples() returns for the same number of input samples. 479 * 480 * @param in_samples number of input samples. 481 * @note any call to swr_inject_silence(), swr_convert(), swr_next_pts() 482 * or swr_set_compensation() invalidates this limit 483 * @note it is recommended to pass the correct available buffer size 484 * to all functions like swr_convert() even if swr_get_out_samples() 485 * indicates that less would be used. 486 * @returns an upper bound on the number of samples that the next swr_convert 487 * will output or a negative value to indicate an error 488 */ 489 int swr_get_out_samples(struct SwrContext *s, int in_samples); 490 491 /** 492 * @} 493 * 494 * @name Configuration accessors 495 * @{ 496 */ 497 498 /** 499 * Return the @ref LIBSWRESAMPLE_VERSION_INT constant. 500 * 501 * This is useful to check if the build-time libswresample has the same version 502 * as the run-time one. 503 * 504 * @returns the unsigned int-typed version 505 */ 506 unsigned swresample_version(void); 507 508 /** 509 * Return the swr build-time configuration. 510 * 511 * @returns the build-time @c ./configure flags 512 */ 513 const char *swresample_configuration(void); 514 515 /** 516 * Return the swr license. 517 * 518 * @returns the license of libswresample, determined at build-time 519 */ 520 const char *swresample_license(void); 521 522 /** 523 * @} 524 * 525 * @name AVFrame based API 526 * @{ 527 */ 528 529 /** 530 * Convert the samples in the input AVFrame and write them to the output AVFrame. 531 * 532 * Input and output AVFrames must have channel_layout, sample_rate and format set. 533 * 534 * If the output AVFrame does not have the data pointers allocated the nb_samples 535 * field will be set using av_frame_get_buffer() 536 * is called to allocate the frame. 537 * 538 * The output AVFrame can be NULL or have fewer allocated samples than required. 539 * In this case, any remaining samples not written to the output will be added 540 * to an internal FIFO buffer, to be returned at the next call to this function 541 * or to swr_convert(). 542 * 543 * If converting sample rate, there may be data remaining in the internal 544 * resampling delay buffer. swr_get_delay() tells the number of 545 * remaining samples. To get this data as output, call this function or 546 * swr_convert() with NULL input. 547 * 548 * If the SwrContext configuration does not match the output and 549 * input AVFrame settings the conversion does not take place and depending on 550 * which AVFrame is not matching AVERROR_OUTPUT_CHANGED, AVERROR_INPUT_CHANGED 551 * or the result of a bitwise-OR of them is returned. 552 * 553 * @see swr_delay() 554 * @see swr_convert() 555 * @see swr_get_delay() 556 * 557 * @param swr audio resample context 558 * @param output output AVFrame 559 * @param input input AVFrame 560 * @return 0 on success, AVERROR on failure or nonmatching 561 * configuration. 562 */ 563 int swr_convert_frame(SwrContext *swr, 564 AVFrame *output, const AVFrame *input); 565 566 /** 567 * Configure or reconfigure the SwrContext using the information 568 * provided by the AVFrames. 569 * 570 * The original resampling context is reset even on failure. 571 * The function calls swr_close() internally if the context is open. 572 * 573 * @see swr_close(); 574 * 575 * @param swr audio resample context 576 * @param out output AVFrame 577 * @param in input AVFrame 578 * @return 0 on success, AVERROR on failure. 579 */ 580 int swr_config_frame(SwrContext *swr, const AVFrame *out, const AVFrame *in); 581 582 /** 583 * @} 584 * @} 585 */ 586 587 #endif /* SWRESAMPLE_SWRESAMPLE_H */