libhb/audio_remap.h

   1 /* audio_remap.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 /* This file handles the following two scenarios:
  11  *
  12  * 1) remapping audio from decoder order to libav order (for downmixing)
  13  *
  14  * 2) remapping audio from libav order to encoder order (for encoding)
  15  *
  16  * We only need to support:
  17  *
  18  * a) channels found in our non-libavcodec audio decoders' layouts
  19  * b) channels found in HB_AMIXDOWN_* layouts
  20  *
  21  * We consider that:
  22  *
  23  * Left/Right Surround == Side Left/Right
  24  * Left/Right Rear Surround == Back Left/Right */
  25
  26 #ifndef AUDIO_REMAP_H
  27 #define AUDIO_REMAP_H
  28
  29 #include <stdint.h>
  30 #include "libavutil/samplefmt.h"
  31
  32 /* we only need to support the 11 "most common" channels */
  33 #define HB_AUDIO_REMAP_MAX_CHANNELS 11
  34
  35 typedef struct
  36 {
  37     uint64_t channel_order_map[HB_AUDIO_REMAP_MAX_CHANNELS + 1];
  38 } hb_chan_map_t;
  39
  40 typedef struct
  41 {
  42     int nchannels;
  43     int remap_needed;
  44     hb_chan_map_t *channel_map_in;
  45     hb_chan_map_t *channel_map_out;
  46     int table[HB_AUDIO_REMAP_MAX_CHANNELS];
  47
  48     void (*remap)(uint8_t **samples, int nsamples,
  49                   int nchannels, int *remap_table);
  50 } hb_audio_remap_t;
  51
  52 /*
  53  * Predefined channel maps for common channel orders.
  54  */
  55 extern hb_chan_map_t hb_libav_chan_map;
  56 extern hb_chan_map_t hb_liba52_chan_map;
  57 extern hb_chan_map_t hb_vorbis_chan_map;
  58 extern hb_chan_map_t hb_aac_chan_map;
  59
  60 /*
  61  * Initialize an hb_audio_remap_t to remap audio with the specified sample
  62  * format, from the input to the output channel order (indicated by
  63  * channel_map_in and channel_map_out, respectively).
  64  */
  65 hb_audio_remap_t* hb_audio_remap_init(enum AVSampleFormat sample_fmt,
  66                                       hb_chan_map_t *channel_map_out,
  67                                       hb_chan_map_t *channel_map_in);
  68
  69 /*
  70  * Updates an hb_audio_remap_t's number of channels and remap table to work with
  71  * the specified channel layout.
  72  *
  73  * Must be called at least once before remapping.
  74  */
  75 void              hb_audio_remap_set_channel_layout(hb_audio_remap_t *remap,
  76                                                     uint64_t channel_layout);
  77
  78 /*
  79  * Free an hb_audio_remap_t.
  80  */
  81 void              hb_audio_remap_free(hb_audio_remap_t *remap);
  82
  83 /*
  84  * Remap audio between 2 different channel orders, using the settings specified
  85  * in the remap paremeter. Remapping is only done when necessary.
  86  *
  87  * The remap parameter can be NULL (no remapping).
  88  */
  89 void              hb_audio_remap(hb_audio_remap_t *remap, uint8_t **samples,
  90                                  int nsamples);
  91
  92 /*
  93  * Generate a table used to remap audio between 2 different channel orders.
  94  *
  95  * Usage: output_sample[channel_idx] = input_sample[remap_table[channel_idx]]
  96  *
  97  * remap_table is allocated by the caller.
  98  */
  99 void              hb_audio_remap_build_table(hb_chan_map_t *channel_map_out,
 100                                              hb_chan_map_t *channel_map_in,
 101                                              uint64_t channel_layout,
 102                                              int *remap_table);
 103
 104 #endif /* AUDIO_REMAP_H */