libhb/audio_resample.h

   1 /* audio_resample.h
   2  *
   3  * Copyright (c) 2003-2015 HandBrake Team
   4  * This file is part of the HandBrake source code
   5  * Homepage: <http://handbrake.fr/>
   6  * It may be used under the terms of the GNU General Public License v2.
   7  * For full terms see the file COPYING file or visit http://www.gnu.org/licenses/gpl-2.0.html
   8  */
   9
  10 /* Implements a libavresample wrapper for convenience.
  11  *
  12  * Supports sample_fmt and channel_layout conversion.
  13  *
  14  * sample_rate conversion will come later (libavresample doesn't support
  15  * sample_rate conversion with float samples yet). */
  16
  17 #ifndef AUDIO_RESAMPLE_H
  18 #define AUDIO_RESAMPLE_H
  19
  20 #include <math.h>
  21 #include <stdint.h>
  22 #include "libavutil/channel_layout.h"
  23 #include "libavresample/avresample.h"
  24
  25 /* Default mix level for center and surround channels */
  26 #define HB_MIXLEV_DEFAULT ((double)M_SQRT1_2)
  27 /* Default mix level for LFE channel */
  28 #define HB_MIXLEV_ZERO    ((double)0.0)
  29
  30 typedef struct
  31 {
  32     int dual_mono_downmix;
  33     int dual_mono_right_only;
  34
  35     int resample_needed;
  36     AVAudioResampleContext *avresample;
  37
  38     struct
  39     {
  40         uint64_t channel_layout;
  41         double lfe_mix_level;
  42         double center_mix_level;
  43         double surround_mix_level;
  44         enum AVSampleFormat sample_fmt;
  45     } in;
  46
  47     struct
  48     {
  49         int channels;
  50         uint64_t channel_layout;
  51         double lfe_mix_level;
  52         double center_mix_level;
  53         double surround_mix_level;
  54         enum AVSampleFormat sample_fmt;
  55     } resample;
  56
  57     struct
  58     {
  59         int channels;
  60         int sample_size;
  61         int normalize_mix_level;
  62         uint64_t channel_layout;
  63         enum AVSampleFormat sample_fmt;
  64         enum AVMatrixEncoding matrix_encoding;
  65     } out;
  66 } hb_audio_resample_t;
  67
  68 /* Initialize an hb_audio_resample_t for converting audio to the requested
  69  * sample_fmt and mixdown.
  70  *
  71  * Also sets the default audio input characteristics, so that they are the same
  72  * as the output characteristics (no conversion needed).
  73  */
  74 hb_audio_resample_t* hb_audio_resample_init(enum AVSampleFormat sample_fmt,
  75                                             int hb_amixdown, int normalize_mix);
  76
  77 /* The following functions set the audio input characteristics.
  78  *
  79  * They should be called whenever the relevant characteristic(s) differ from the
  80  * requested output characteristics, or if they may have changed in the source.
  81  */
  82
  83 void                 hb_audio_resample_set_channel_layout(hb_audio_resample_t *resample,
  84                                                           uint64_t channel_layout);
  85
  86 void                 hb_audio_resample_set_mix_levels(hb_audio_resample_t *resample,
  87                                                       double surround_mix_level,
  88                                                       double center_mix_level,
  89                                                       double lfe_mix_level);
  90
  91 void                 hb_audio_resample_set_sample_fmt(hb_audio_resample_t *resample,
  92                                                       enum AVSampleFormat sample_fmt);
  93
  94 /* Update an hb_audio_resample_t.
  95  *
  96  * Must be called after using any of the above functions.
  97  */
  98 int                  hb_audio_resample_update(hb_audio_resample_t *resample);
  99
 100 /* Free an hb_audio_remsample_t. */
 101 void                 hb_audio_resample_free(hb_audio_resample_t *resample);
 102
 103 /* Convert input samples to the requested output characteristics
 104  * (sample_fmt and channel_layout + matrix_encoding).
 105  *
 106  * Returns an hb_buffer_t with the converted output.
 107  *
 108  * resampling is only done when necessary.
 109  */
 110 hb_buffer_t*         hb_audio_resample(hb_audio_resample_t *resample,
 111                                        uint8_t **samples, int nsamples);
 112
 113 #endif /* AUDIO_RESAMPLE_H */