Add support for channel transforms.

media/base/channel_layout.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/channel_layout.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 
 namespace media {
 
 static const int kLayoutToChannels[] = {
     0,   // CHANNEL_LAYOUT_NONE
     0,   // CHANNEL_LAYOUT_UNSUPPORTED
     1,   // CHANNEL_LAYOUT_MONO
     2,   // CHANNEL_LAYOUT_STEREO
     3,   // CHANNEL_LAYOUT_2_1
     3,   // CHANNEL_LAYOUT_SURROUND
     4,   // CHANNEL_LAYOUT_4POINT0
     4,   // CHANNEL_LAYOUT_2_2
     4,   // CHANNEL_LAYOUT_QUAD
     5,   // CHANNEL_LAYOUT_5POINT0
     6,   // CHANNEL_LAYOUT_5POINT1
     5,   // CHANNEL_LAYOUT_5POINT0_BACK
     6,   // CHANNEL_LAYOUT_5POINT1_BACK
     7,   // CHANNEL_LAYOUT_7POINT0
     8,   // CHANNEL_LAYOUT_7POINT1
     8,   // CHANNEL_LAYOUT_7POINT1_WIDE
-    2};  // CHANNEL_LAYOUT_STEREO_DOWNMIX
+    2,   // CHANNEL_LAYOUT_STEREO_DOWNMIX
+};
 
 // The channel orderings for each layout as specified by FFmpeg.  Each value
 // represents the index of each channel in each layout.  Values of -1 mean the
 // channel at that index is not used for that layout.For example, the left side
 // surround sound channel in FFmpeg's 5.1 layout is in the 5th position (because
 // the order is L, R, C, LFE, LS, RS), so
 // kChannelOrderings[CHANNEL_LAYOUT_5POINT1][SIDE_LEFT] = 4;
 static const int kChannelOrderings[CHANNEL_LAYOUT_MAX][CHANNELS_MAX] = {
-  // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR | StL | StR
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
 
-  // CHANNEL_LAYOUT_NONE
-  {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_NONE
+    {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_UNSUPPORTED
-  {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_UNSUPPORTED
+    {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_MONO
-  {  -1 , -1 , 0  , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_MONO
+    {  -1 , -1 , 0  , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_STEREO
-  {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_STEREO
+    {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_2_1
-  {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , 2  , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_2_1
+    {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , 2  , -1 , -1 },
 
-  // CHANNEL_LAYOUT_SURROUND
-  {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_SURROUND
+    {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_4POINT0
-  {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , 3  , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_4POINT0
+    {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , 3  , -1 , -1 },
 
-  // CHANNEL_LAYOUT_2_2
-  {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , -1 , 2  , 3  , -1  , -1 },
+    // CHANNEL_LAYOUT_2_2
+    {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , -1 , 2  ,  3 },
 
-  // CHANNEL_LAYOUT_QUAD
-  {  0  , 1  , -1 , -1  , 2  , 3  , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_QUAD
+    {  0  , 1  , -1 , -1  , 2  , 3  , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_5POINT0
-  {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , -1 , 3  , 4  , -1  , -1 },
+    // CHANNEL_LAYOUT_5POINT0
+    {  0  , 1  , 2  , -1  , -1 , -1 , -1    , -1    , -1 , 3  ,  4 },
 
-  // CHANNEL_LAYOUT_5POINT1
-  {  0  , 1  , 2  , 3   , -1 , -1 , -1    , -1    , -1 , 4  , 5  , -1  , -1 },
+    // CHANNEL_LAYOUT_5POINT1
+    {  0  , 1  , 2  , 3   , -1 , -1 , -1    , -1    , -1 , 4  ,  5 },
 
-  // CHANNEL_LAYOUT_5POINT0_BACK
-  {  0  , 1  , 2  , -1  , 3  , 4  , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_5POINT0_BACK
+    {  0  , 1  , 2  , -1  , 3  , 4  , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_5POINT1_BACK
-  {  0  , 1  , 2  , 3   , 4  , 5  , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_5POINT1_BACK
+    {  0  , 1  , 2  , 3   , 4  , 5  , -1    , -1    , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_7POINT0
-  {  0  , 1  , 2  , -1  , 5  , 6  , -1    , -1    , -1 , 3  , 4  , -1  , -1 },
+    // CHANNEL_LAYOUT_7POINT0
+    {  0  , 1  , 2  , -1  , 5  , 6  , -1    , -1    , -1 , 3  ,  4 },
 
-  // CHANNEL_LAYOUT_7POINT1
-  {  0  , 1  , 2  , 3   , 6  , 7  , -1    , -1    , -1 , 4  , 5  , -1  , -1 },
+    // CHANNEL_LAYOUT_7POINT1
+    {  0  , 1  , 2  , 3   , 6  , 7  , -1    , -1    , -1 , 4  ,  5 },
 
-  // CHANNEL_LAYOUT_7POINT1_WIDE
-  {  0  , 1  , 2  , 3   , 4  , 5  , 6     , 7     , -1 , -1 , -1 , -1  , -1 },
+    // CHANNEL_LAYOUT_7POINT1_WIDE
+    {  0  , 1  , 2  , 3   , 4  , 5  , 6     , 7     , -1 , -1 , -1 },
 
-  // CHANNEL_LAYOUT_STEREO_DOWNMIX
-  {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , 0   , 1  },
+    // CHANNEL_LAYOUT_STEREO_DOWNMIX
+    {  0  , 1  , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 },
 
-  // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR | StL | StR
-  };
+    // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR
+};
 
 int ChannelLayoutToChannelCount(ChannelLayout layout) {
   DCHECK_LT(static_cast<size_t>(layout), arraysize(kLayoutToChannels));
   return kLayoutToChannels[layout];
 }
 
 int ChannelOrder(ChannelLayout layout, Channels channel) {
   DCHECK_LT(static_cast<size_t>(layout), arraysize(kChannelOrderings));
   DCHECK_LT(static_cast<size_t>(channel), arraysize(kChannelOrderings[0]));
   return kChannelOrderings[layout][channel];
 }
 
 }  // namespace media