media: Support multichannel Opus audio streams.

Add conversion code that supports going from a number of channels to a
channel layout for Opus audio, which prevents failure of
AudioDecoderConfig::IsValidConfig() for all multichannel Opus streams.
Also fixes audio channel layout for 6.1 (7) channel Opus streams.

BUG=172744
TEST=Opus streams with greater than 2 channels play.


Review URL: https://chromiumcodereview.appspot.com/12094019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@179760 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 35 insertions, 6 deletions

diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index 800c027..b5e4100 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -261,6 +261,31 @@ static AVSampleFormat SampleFormatToAVSampleFormat(SampleFormat sample_format) {
   return AV_SAMPLE_FMT_NONE;
 }
 
+ChannelLayout OpusChannelCountToChromeChannelLayout(int channels) {
+  switch (channels) {
+    case 1:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_MONO, channels);
+    case 2:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_STEREO, channels);
+    case 3:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_SURROUND,
+                                                channels);
+    case 4:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_QUAD, channels);
+    case 5:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_5POINT0, channels);
+    case 6:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_5POINT1, channels);
+    case 7:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_6POINT1, channels);
+    case 8:
+      return ChannelLayoutToChromeChannelLayout(AV_CH_LAYOUT_7POINT1, channels);
+    default:
+      LOG(ERROR) << "Unsupported Opus channel count: " << channels;
+  }
+  return CHANNEL_LAYOUT_UNSUPPORTED;
+}
+
 void AVCodecContextToAudioDecoderConfig(
     const AVCodecContext* codec_context,
     AudioDecoderConfig* config) {
@@ -271,16 +296,20 @@ void AVCodecContextToAudioDecoderConfig(
   SampleFormat sample_format =
       AVSampleFormatToSampleFormat(codec_context->sample_fmt);
 
+  ChannelLayout channel_layout = ChannelLayoutToChromeChannelLayout(
+      codec_context->channel_layout, codec_context->channels);
+
   if (codec == kCodecOpus) {
-    // TODO(tomfinegan): |sample_fmt| in |codec_context| is -1... because
-    // libopusdec.c isn't built into ffmpegsumo...? Maybe it's not *that* big
-    // a deal since libopus will produce either float or S16 samples, and
-    // OpusAudioDecoder is the only provider of Opus support.
+    // |channel_layout| and |sample_fmt| in |codec_context| are not set by
+    // FFmpeg. This happens because Opus is not enabled in ffmpegsumo. This is
+    // not that big a deal, because:
+    // 1. OpusAudioDecoder always uses signed 16 bit samples, and...
+    // 2. OpusAudioDecoder outputs audio using the same channel order as FFmpeg.
     sample_format = kSampleFormatS16;
+    channel_layout =
+        OpusChannelCountToChromeChannelLayout(codec_context->channels);
   }
 
-  ChannelLayout channel_layout = ChannelLayoutToChromeChannelLayout(
-      codec_context->channel_layout, codec_context->channels);
   config->Initialize(codec,
                      sample_format,
                      channel_layout,