media/base/channel_layout.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_BASE_CHANNEL_LAYOUT_H_
   6 #define MEDIA_BASE_CHANNEL_LAYOUT_H_
   7
   8 #include "media/base/media_export.h"
   9
  10 namespace media {
  11
  12 // Enumerates the various representations of the ordering of audio channels.
  13 // Logged to UMA, so never reuse a value, always add new/greater ones!
  14 enum ChannelLayout {
  15   CHANNEL_LAYOUT_NONE = 0,
  16   CHANNEL_LAYOUT_UNSUPPORTED = 1,
  17
  18   // Front C
  19   CHANNEL_LAYOUT_MONO = 2,
  20
  21   // Front L, Front R
  22   CHANNEL_LAYOUT_STEREO = 3,
  23
  24   // Front L, Front R, Back C
  25   CHANNEL_LAYOUT_2_1 = 4,
  26
  27   // Front L, Front R, Front C
  28   CHANNEL_LAYOUT_SURROUND = 5,
  29
  30   // Front L, Front R, Front C, Back C
  31   CHANNEL_LAYOUT_4_0 = 6,
  32
  33   // Front L, Front R, Side L, Side R
  34   CHANNEL_LAYOUT_2_2 = 7,
  35
  36   // Front L, Front R, Back L, Back R
  37   CHANNEL_LAYOUT_QUAD = 8,
  38
  39   // Front L, Front R, Front C, Side L, Side R
  40   CHANNEL_LAYOUT_5_0 = 9,
  41
  42   // Front L, Front R, Front C, Side L, Side R, LFE
  43   CHANNEL_LAYOUT_5_1 = 10,
  44
  45   // Front L, Front R, Front C, Back L, Back R
  46   CHANNEL_LAYOUT_5_0_BACK = 11,
  47
  48   // Front L, Front R, Front C, Back L, Back R, LFE
  49   CHANNEL_LAYOUT_5_1_BACK = 12,
  50
  51   // Front L, Front R, Front C, Side L, Side R, Back L, Back R
  52   CHANNEL_LAYOUT_7_0 = 13,
  53
  54   // Front L, Front R, Front C, Side L, Side R, LFE, Back L, Back R
  55   CHANNEL_LAYOUT_7_1 = 14,
  56
  57   // Front L, Front R, Front C, Side L, Side R, LFE, Front LofC, Front RofC
  58   CHANNEL_LAYOUT_7_1_WIDE = 15,
  59
  60   // Stereo L, Stereo R
  61   CHANNEL_LAYOUT_STEREO_DOWNMIX = 16,
  62
  63   // Stereo L, Stereo R, LFE
  64   CHANNEL_LAYOUT_2POINT1 = 17,
  65
  66   // Stereo L, Stereo R, Front C, LFE
  67   CHANNEL_LAYOUT_3_1 = 18,
  68
  69   // Stereo L, Stereo R, Front C, Rear C, LFE
  70   CHANNEL_LAYOUT_4_1 = 19,
  71
  72   // Stereo L, Stereo R, Front C, Side L, Side R, Back C
  73   CHANNEL_LAYOUT_6_0 = 20,
  74
  75   // Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC
  76   CHANNEL_LAYOUT_6_0_FRONT = 21,
  77
  78   // Stereo L, Stereo R, Side L, Side R, Front C, Rear C.
  79   CHANNEL_LAYOUT_HEXAGONAL = 22,
  80
  81   // Stereo L, Stereo R, Side L, Side R, Front C, Rear Center, LFE
  82   CHANNEL_LAYOUT_6_1 = 23,
  83
  84   // Stereo L, Stereo R, Back L, Back R, Front C, Rear Center, LFE
  85   CHANNEL_LAYOUT_6_1_BACK = 24,
  86
  87   // Stereo L, Stereo R, Side L, Side R, Front LofC, Front RofC, LFE
  88   CHANNEL_LAYOUT_6_1_FRONT = 25,
  89
  90   // Front L, Front R, Front C, Side L, Side R, Front LofC, Front RofC
  91   CHANNEL_LAYOUT_7_0_FRONT = 26,
  92
  93   // Front L, Front R, Front C, Back L, Back R, LFE, Front LofC, Front RofC
  94   CHANNEL_LAYOUT_7_1_WIDE_BACK = 27,
  95
  96   // Front L, Front R, Front C, Side L, Side R, Rear C, Back L, Back R.
  97   CHANNEL_LAYOUT_OCTAGONAL = 28,
  98
  99   // Channels are not explicitly mapped to speakers.
 100   CHANNEL_LAYOUT_DISCRETE = 29,
 101
 102   // Total number of layouts.
 103   CHANNEL_LAYOUT_MAX  // Must always be last!
 104 };
 105
 106 enum Channels {
 107   LEFT = 0,
 108   RIGHT,
 109   CENTER,
 110   LFE,
 111   BACK_LEFT,
 112   BACK_RIGHT,
 113   LEFT_OF_CENTER,
 114   RIGHT_OF_CENTER,
 115   BACK_CENTER,
 116   SIDE_LEFT,
 117   SIDE_RIGHT,
 118   CHANNELS_MAX
 119 };
 120
 121 // Returns the expected channel position in an interleaved stream.  Values of -1
 122 // mean the channel at that index is not used for that layout.  Values range
 123 // from 0 to CHANNELS_MAX - 1.
 124 MEDIA_EXPORT int ChannelOrder(ChannelLayout layout, Channels channel);
 125
 126 // Returns the number of channels in a given ChannelLayout.
 127 MEDIA_EXPORT int ChannelLayoutToChannelCount(ChannelLayout layout);
 128
 129 // Given the number of channels, return the best layout,
 130 // or return CHANNEL_LAYOUT_UNSUPPORTED if there is no good match.
 131 MEDIA_EXPORT ChannelLayout GuessChannelLayout(int channels);
 132
 133 // Returns a string representation of the channel layout.
 134 MEDIA_EXPORT const char* ChannelLayoutToString(ChannelLayout layout);
 135
 136 }  // namespace media
 137
 138 #endif  // MEDIA_BASE_CHANNEL_LAYOUT_H_