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/* audio_resample.h
*
* Copyright (c) 2003-2018 HandBrake Team
* This file is part of the HandBrake source code
* Homepage: <http://handbrake.fr/>
* It may be used under the terms of the GNU General Public License v2.
* For full terms see the file COPYING file or visit http://www.gnu.org/licenses/gpl-2.0.html
*/
/* Implements a libswresample wrapper for convenience.
*
* Supports sample_fmt and channel_layout conversion.
*
* sample_rate conversion will come later (libswresample doesn't support
* sample_rate conversion with float samples yet). */
#ifndef AUDIO_RESAMPLE_H
#define AUDIO_RESAMPLE_H
#include <math.h>
#include <stdint.h>
#include "libavutil/channel_layout.h"
#include "libswresample/swresample.h"
/* Default mix level for center and surround channels */
#define HB_MIXLEV_DEFAULT ((double)M_SQRT1_2)
/* Default mix level for LFE channel */
#define HB_MIXLEV_ZERO ((double)0.0)
typedef struct
{
int dual_mono_downmix;
int dual_mono_right_only;
int resample_needed;
SwrContext *swresample;
struct
{
uint64_t channel_layout;
double lfe_mix_level;
double center_mix_level;
double surround_mix_level;
enum AVSampleFormat sample_fmt;
} in;
struct
{
int channels;
uint64_t channel_layout;
double lfe_mix_level;
double center_mix_level;
double surround_mix_level;
enum AVSampleFormat sample_fmt;
} resample;
struct
{
int channels;
int sample_size;
uint64_t channel_layout;
enum AVSampleFormat sample_fmt;
enum AVMatrixEncoding matrix_encoding;
double maxval;
} out;
} hb_audio_resample_t;
/* Initialize an hb_audio_resample_t for converting audio to the requested
* sample_fmt and mixdown.
*
* Also sets the default audio input characteristics, so that they are the same
* as the output characteristics (no conversion needed).
*/
hb_audio_resample_t* hb_audio_resample_init(enum AVSampleFormat sample_fmt,
int hb_amixdown, int normalize_mix);
/* The following functions set the audio input characteristics.
*
* They should be called whenever the relevant characteristic(s) differ from the
* requested output characteristics, or if they may have changed in the source.
*/
void hb_audio_resample_set_channel_layout(hb_audio_resample_t *resample,
uint64_t channel_layout);
void hb_audio_resample_set_mix_levels(hb_audio_resample_t *resample,
double surround_mix_level,
double center_mix_level,
double lfe_mix_level);
void hb_audio_resample_set_sample_fmt(hb_audio_resample_t *resample,
enum AVSampleFormat sample_fmt);
/* Update an hb_audio_resample_t.
*
* Must be called after using any of the above functions.
*/
int hb_audio_resample_update(hb_audio_resample_t *resample);
/* Free an hb_audio_remsample_t. */
void hb_audio_resample_free(hb_audio_resample_t *resample);
/* Convert input samples to the requested output characteristics
* (sample_fmt and channel_layout + matrix_encoding).
*
* Returns an hb_buffer_t with the converted output.
*
* resampling is only done when necessary.
*/
hb_buffer_t* hb_audio_resample(hb_audio_resample_t *resample,
const uint8_t **samples, int nsamples);
#endif /* AUDIO_RESAMPLE_H */
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