2 * Copyright (C) 2011-2012 Michael Niedermayer (michaelni@gmx.at)
4 * This file is part of libswresample
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.
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.
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
21 #ifndef SWRESAMPLE_SWRESAMPLE_H
22 #define SWRESAMPLE_SWRESAMPLE_H
26 * libswresample public header
30 * @defgroup lswr Libswresample
33 * Libswresample (lswr) is a library that handles audio resampling, sample
34 * format conversion and mixing.
36 * Interaction with lswr is done through SwrContext, which is
37 * allocated with swr_alloc() or swr_alloc_set_opts(). It is opaque, so all parameters
38 * must be set with the @ref avoptions API.
40 * For example the following code will setup conversion from planar float sample
41 * format to interleaved signed 16-bit integer, downsampling from 48kHz to
42 * 44.1kHz and downmixing from 5.1 channels to stereo (using the default mixing
45 * SwrContext *swr = swr_alloc();
46 * av_opt_set_int(swr, "in_channel_layout", AV_CH_LAYOUT_5POINT1, 0);
47 * av_opt_set_int(swr, "out_channel_layout", AV_CH_LAYOUT_STEREO, 0);
48 * av_opt_set_int(swr, "in_sample_rate", 48000, 0);
49 * av_opt_set_int(swr, "out_sample_rate", 44100, 0);
50 * av_opt_set_sample_fmt(swr, "in_sample_fmt", AV_SAMPLE_FMT_FLTP, 0);
51 * av_opt_set_sample_fmt(swr, "out_sample_fmt, AV_SAMPLE_FMT_S16, 0);
54 * Once all values have been set, it must be initialized with swr_init(). If
55 * you need to change the conversion parameters, you can change the parameters
56 * as described above, or by using swr_alloc_set_opts(), then call swr_init()
59 * The conversion itself is done by repeatedly calling swr_convert().
60 * Note that the samples may get buffered in swr if you provide insufficient
61 * output space or if sample rate conversion is done, which requires "future"
62 * samples. Samples that do not require future input can be retrieved at any
63 * time by using swr_convert() (in_count can be set to 0).
64 * At the end of conversion the resampling buffer can be flushed by calling
65 * swr_convert() with NULL in and 0 in_count.
67 * The delay between input and output, can at any time be found by using
70 * The following code demonstrates the conversion loop assuming the parameters
71 * from above and caller-defined functions get_input() and handle_output():
76 * while (get_input(&input, &in_samples)) {
78 * int out_samples = av_rescale_rnd(swr_get_delay(swr, 48000) +
79 * in_samples, 44100, 48000, AV_ROUND_UP);
80 * av_samples_alloc(&output, NULL, 2, out_samples,
81 * AV_SAMPLE_FMT_S16, 0);
82 * out_samples = swr_convert(swr, &output, out_samples,
84 * handle_output(output, out_samples);
89 * When the conversion is finished, the conversion
90 * context and everything associated with it must be freed with swr_free().
91 * There will be no memory leak if the data is not completely flushed before
96 #include "libavutil/samplefmt.h"
98 #include "libswresample/version.h"
100 #if LIBSWRESAMPLE_VERSION_MAJOR < 1
101 #define SWR_CH_MAX 32 ///< Maximum number of channels
104 #define SWR_FLAG_RESAMPLE 1 ///< Force resampling even if equal sample rate
105 //TODO use int resample ?
106 //long term TODO can we enable this dynamically?
110 SWR_DITHER_RECTANGULAR,
111 SWR_DITHER_TRIANGULAR,
112 SWR_DITHER_TRIANGULAR_HIGHPASS,
113 SWR_DITHER_NB, ///< not part of API/ABI
116 /** Resampling Filter Types */
118 SWR_FILTER_TYPE_CUBIC, /**< Cubic */
119 SWR_FILTER_TYPE_BLACKMAN_NUTTALL, /**< Blackman Nuttall Windowed Sinc */
120 SWR_FILTER_TYPE_KAISER, /**< Kaiser Windowed Sinc */
123 typedef struct SwrContext SwrContext;
126 * Get the AVClass for swrContext. It can be used in combination with
127 * AV_OPT_SEARCH_FAKE_OBJ for examining options.
129 * @see av_opt_find().
131 const AVClass *swr_get_class(void);
134 * Allocate SwrContext.
136 * If you use this function you will need to set the parameters (manually or
137 * with swr_alloc_set_opts()) before calling swr_init().
139 * @see swr_alloc_set_opts(), swr_init(), swr_free()
140 * @return NULL on error, allocated context otherwise
142 struct SwrContext *swr_alloc(void);
145 * Initialize context after user parameters have been set.
147 * @return AVERROR error code in case of failure.
149 int swr_init(struct SwrContext *s);
152 * Allocate SwrContext if needed and set/reset common parameters.
154 * This function does not require s to be allocated with swr_alloc(). On the
155 * other hand, swr_alloc() can use swr_alloc_set_opts() to set the parameters
156 * on the allocated context.
158 * @param s Swr context, can be NULL
159 * @param out_ch_layout output channel layout (AV_CH_LAYOUT_*)
160 * @param out_sample_fmt output sample format (AV_SAMPLE_FMT_*).
161 * @param out_sample_rate output sample rate (frequency in Hz)
162 * @param in_ch_layout input channel layout (AV_CH_LAYOUT_*)
163 * @param in_sample_fmt input sample format (AV_SAMPLE_FMT_*).
164 * @param in_sample_rate input sample rate (frequency in Hz)
165 * @param log_offset logging level offset
166 * @param log_ctx parent logging context, can be NULL
168 * @see swr_init(), swr_free()
169 * @return NULL on error, allocated context otherwise
171 struct SwrContext *swr_alloc_set_opts(struct SwrContext *s,
172 int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate,
173 int64_t in_ch_layout, enum AVSampleFormat in_sample_fmt, int in_sample_rate,
174 int log_offset, void *log_ctx);
177 * Free the given SwrContext and set the pointer to NULL.
179 void swr_free(struct SwrContext **s);
184 * in and in_count can be set to 0 to flush the last few samples out at the
187 * If more input is provided than output space then the input will be buffered.
188 * You can avoid this buffering by providing more output space than input.
189 * Convertion will run directly without copying whenever possible.
191 * @param s allocated Swr context, with parameters set
192 * @param out output buffers, only the first one need be set in case of packed audio
193 * @param out_count amount of space available for output in samples per channel
194 * @param in input buffers, only the first one need to be set in case of packed audio
195 * @param in_count number of input samples available in one channel
197 * @return number of samples output per channel, negative value on error
199 int swr_convert(struct SwrContext *s, uint8_t **out, int out_count,
200 const uint8_t **in , int in_count);
203 * Convert the next timestamp from input to output
204 * timestamps are in 1/(in_sample_rate * out_sample_rate) units.
206 * @note There are 2 slightly differently behaving modes.
207 * First is when automatic timestamp compensation is not used, (min_compensation >= FLT_MAX)
208 * in this case timestamps will be passed through with delays compensated
209 * Second is when automatic timestamp compensation is used, (min_compensation < FLT_MAX)
210 * in this case the output timestamps will match output sample numbers
212 * @param pts timestamp for the next input sample, INT64_MIN if unknown
213 * @return the output timestamp for the next output sample
215 int64_t swr_next_pts(struct SwrContext *s, int64_t pts);
218 * Activate resampling compensation.
220 int swr_set_compensation(struct SwrContext *s, int sample_delta, int compensation_distance);
223 * Set a customized input channel mapping.
225 * @param s allocated Swr context, not yet initialized
226 * @param channel_map customized input channel mapping (array of channel
227 * indexes, -1 for a muted channel)
228 * @return AVERROR error code in case of failure.
230 int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map);
233 * Set a customized remix matrix.
235 * @param s allocated Swr context, not yet initialized
236 * @param matrix remix coefficients; matrix[i + stride * o] is
237 * the weight of input channel i in output channel o
238 * @param stride offset between lines of the matrix
239 * @return AVERROR error code in case of failure.
241 int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride);
244 * Drops the specified number of output samples.
246 int swr_drop_output(struct SwrContext *s, int count);
249 * Injects the specified number of silence samples.
251 int swr_inject_silence(struct SwrContext *s, int count);
254 * Gets the delay the next input sample will experience relative to the next output sample.
256 * Swresample can buffer data if more input has been provided than available
257 * output space, also converting between sample rates needs a delay.
258 * This function returns the sum of all such delays.
259 * The exact delay is not necessarily an integer value in either input or
260 * output sample rate. Especially when downsampling by a large value, the
261 * output sample rate may be a poor choice to represent the delay, similarly
262 * for upsampling and the input sample rate.
264 * @param s swr context
265 * @param base timebase in which the returned delay will be
266 * if its set to 1 the returned delay is in seconds
267 * if its set to 1000 the returned delay is in milli seconds
268 * if its set to the input sample rate then the returned delay is in input samples
269 * if its set to the output sample rate then the returned delay is in output samples
270 * an exact rounding free delay can be found by using LCM(in_sample_rate, out_sample_rate)
271 * @returns the delay in 1/base units.
273 int64_t swr_get_delay(struct SwrContext *s, int64_t base);
276 * Return the LIBSWRESAMPLE_VERSION_INT constant.
278 unsigned swresample_version(void);
281 * Return the swr build-time configuration.
283 const char *swresample_configuration(void);
286 * Return the swr license.
288 const char *swresample_license(void);
294 #endif /* SWRESAMPLE_SWRESAMPLE_H */