Add Opus decode wrapper to media.

webkit/media/filter_helpers.cc

Index: webkit/media/filter_helpers.cc
diff --git a/webkit/media/filter_helpers.cc b/webkit/media/filter_helpers.cc
index 379e2caad4a2cf7c31ff5b2cd825a747c2e8fc61..e584f9c51b628a19bba9357f414b2400aef678fa 100644
--- a/webkit/media/filter_helpers.cc
+++ b/webkit/media/filter_helpers.cc
@@ -5,7 +5,9 @@
 #include "webkit/media/filter_helpers.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "media/base/filter_collection.h"
+#include "media/base/media_switches.h"
 #include "media/filters/decrypting_audio_decoder.h"
 #include "media/filters/decrypting_video_decoder.h"
 #include "media/filters/chunk_demuxer.h"
@@ -13,6 +15,7 @@
 #include "media/filters/ffmpeg_audio_decoder.h"
 #include "media/filters/ffmpeg_demuxer.h"
 #include "media/filters/ffmpeg_video_decoder.h"
+#include "media/filters/opus_audio_decoder.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebURL.h"
 #include "webkit/media/crypto/proxy_decryptor.h"
 #include "webkit/media/media_stream_client.h"
@@ -30,6 +33,14 @@ static void AddDefaultDecodersToCollection(
     const scoped_refptr<base::MessageLoopProxy>& message_loop,
     media::FilterCollection* filter_collection,
     ProxyDecryptor* proxy_decryptor) {
+
+  const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  if (cmd_line->HasSwitch(switches::kEnableVp9OpusPlayback)) {
+    scoped_refptr<media::OpusAudioDecoder> opus_audio_decoder =
+        new media::OpusAudioDecoder(message_loop);
+    filter_collection->GetAudioDecoders()->push_back(opus_audio_decoder);
+  }

[xhwang, 2012/12/14 08:41:48]

media pipeline tries each audio decoder in the order they are pushed until an
audio decoder that can decode certain input stream is found. since in most cases
audio is not opus (and I assume FFmpegAudioDecoder cannot decode opus?), can we
move this block to line 47?

[Tom Finegan, 2012/12/14 20:21:34]

Done.

+
   scoped_refptr<media::FFmpegAudioDecoder> ffmpeg_audio_decoder =
       new media::FFmpegAudioDecoder(message_loop);
   filter_collection->GetAudioDecoders()->push_back(ffmpeg_audio_decoder);