Move ChannelLayout into media namespace.

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
 
-const int kChannelOrderings[CHANNEL_LAYOUT_MAX][CHANNELS_MAX] = {
+// 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
 
   // CHANNEL_LAYOUT_NONE
   {  -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 , -1  , -1 },
 
   // CHANNEL_LAYOUT_MONO
   {  -1 , -1 , 0  , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , -1  , -1 },
@@ skipping 37 matching lines @@
   // CHANNEL_LAYOUT_7POINT1_WIDE
   {  0  , 1  , 2  , 3   , 4  , 5  , 6     , 7     , -1 , -1 , -1 , -1  , -1 },
 
   // CHANNEL_LAYOUT_STEREO_DOWNMIX
   {  -1 , -1 , -1 , -1  , -1 , -1 , -1    , -1    , -1 , -1 , -1 , 0   , 1  },
 
   // FL | FR | FC | LFE | BL | BR | FLofC | FRofC | BC | SL | SR | StL | StR
   };
 
 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