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>
125
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 */
149
159 };
160
161 /** Resampling Engines */
166 };
167
168 /** Resampling Filter Types */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
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 */
449
450 /**
451 * Return the swr build-time configuration.
452 *
453 * @returns the build-time @c ./configure flags
454 */
456
457 /**
458 * Return the swr license.
459 *
460 * @returns the license of libswresample, determined at build-time
461 */
463
464 /**
465 * @}
466 * @}
467 */
468
469 #endif /* SWRESAMPLE_SWRESAMPLE_H */