---
libavresample/avresample.h | 70 ++++++++++++++++++++++++++++++++++++++++++++
libavutil/avutil.h | 1 +
2 files changed, 71 insertions(+), 0 deletions(-)
diff --git a/libavresample/avresample.h b/libavresample/avresample.h
index ea93952..902d239 100644
--- a/libavresample/avresample.h
+++ b/libavresample/avresample.h
@@ -23,9 +23,75 @@
/**
* @file
+ * @ingroup lavr
* external API header
*/
+/**
+ * @defgroup lavr Libavresample
+ * @{
+ *
+ * Libavresample (lavr) is a library that handles audio resampling, sample
+ * format conversion and mixing.
+ *
+ * Interaction with lavr is done through AVAudioResampleContext, which is
+ * allocated with avresample_alloc_context(). It is opaque, so all parameters
+ * must be set with the @ref avoptions API.
+ *
+ * E.g. the following code will setup conversion from planar float sample
format
+ * to interleaved signed 16-bit integer, downsampling from 48kHz to 44.1kHz and
+ * downmixing from 5.1 channels to stereo (using the default mixing matrix):
+ * @code
+ * AVAudioResampleContext *avr = avresample_alloc_context();
+ * av_opt_set_int(avr, "in_channel_layout", AV_CH_LAYOUT_5POINT1, 0);
+ * av_opt_set_int(avr, "out_channel_layout", AV_CH_LAYOUT_STEREO, 0);
+ * av_opt_set_int(avr, "in_sample_rate", 48000, 0);
+ * av_opt_set_int(avr, "out_sample_rate", 44100, 0);
+ * av_opt_set_int(avr, "in_sample_fmt", AV_SAMPLE_FMT_FLTP, 0);
+ * av_opt_set_int(avr, "out_sample_fmt, AV_SAMPLE_FMT_S16, 0);
+ * @endcode
+ *
+ * Once the context is initialized, it must be opened with avresample_open().
If
+ * you need to change the conversion parameters, you must close the context
with
+ * avresample_close(), change the parameters as described above, then reopen it
+ * again.
+ *
+ * The conversion itself is done by repeatedly calling avresample_convert().
+ * Note that the samples may get buffered in two places in lavr. The first one
+ * is the output FIFO, where the samples end up if the output buffer is not
+ * large enough. The data stored in there may be retrieved at any time with
+ * avresample_read(). The second place is the resampling delay buffer,
+ * applicable only when resampling is done. The samples in it require more
input
+ * before they can be processed. Their current amount is returned by
+ * avresample_get_delay(). At the end of conversion the resampling buffer can
be
+ * flushed by calling avresample_convert() with NULL input.
+ *
+ * The following code demonstrates the conversion loop assuming the parameters
+ * from above and caller-defined functions get_input() and handle_output():
+ * @code
+ * uint8_t **input;
+ * int in_linesize, in_samples;
+ *
+ * while (get_input(&input, &in_linesize, &in_samples)) {
+ * uint8_t *output
+ * int out_linesize;
+ * int out_samples = avresample_available(avr) +
+ * av_rescale_rnd(avresample_get_delay(avr) +
+ * in_samples, 44100, 48000, AV_ROUND_UP);
+ * av_samples_alloc(&output, &out_linesize, 2, out_samples,
+ * AV_SAMPLE_FMT_S16, 0);
+ * out_samples = avresample_convert(avr, &output, out_linesize,
out_samples,
+ * input, in_linesize, in_samples);
+ * handle_output(output, out_linesize, out_samples);
+ * av_freep(&output);
+ * }
+ * @endcode
+ *
+ * When the conversion is finished and the FIFOs are flushed if required, the
+ * conversion context and everything associated with it must be freed with
+ * avresample_free().
+ */
+
#include "libavutil/audioconvert.h"
#include "libavutil/avutil.h"
#include "libavutil/dict.h"
@@ -289,4 +355,8 @@ int avresample_available(AVAudioResampleContext *avr);
*/
int avresample_read(AVAudioResampleContext *avr, uint8_t **output, int
nb_samples);
+/**
+ * @}
+ */
+
#endif /* AVRESAMPLE_AVRESAMPLE_H */
diff --git a/libavutil/avutil.h b/libavutil/avutil.h
index a1433b4..33f9bea 100644
--- a/libavutil/avutil.h
+++ b/libavutil/avutil.h
@@ -39,6 +39,7 @@
* @li @ref libavf "libavformat" I/O and muxing/demuxing library
* @li @ref lavd "libavdevice" special devices muxing/demuxing library
* @li @ref lavu "libavutil" common utility library
+ * @li @ref lavr "libavresample" audio resampling, format conversion and mixing
* @li @subpage libswscale color conversion and scaling library
*/
--
1.7.8.3
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