Render inband text tracks in the media pipeline

content/renderer/media/webmediaplayer_impl.h

Index: content/renderer/media/webmediaplayer_impl.h
diff --git a/content/renderer/media/webmediaplayer_impl.h b/content/renderer/media/webmediaplayer_impl.h
index 270186bbbe5aad43fce9d7c4d3ee8a7c4977fab2..266b3f4642d1938d80f42be6c179c2e11f4f0630 100644
--- a/content/renderer/media/webmediaplayer_impl.h
+++ b/content/renderer/media/webmediaplayer_impl.h
@@ -20,6 +20,7 @@
 #ifndef CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_WEBMEDIAPLAYER_IMPL_H_
 
+#include <map>
 #include <string>
 #include <vector>
 
@@ -58,6 +59,7 @@ class ChunkDemuxer;
 class FFmpegDemuxer;
 class GpuVideoAcceleratorFactories;
 class MediaLog;
+class TextBuffer;
 }
 
 namespace webkit {
@@ -200,6 +202,10 @@ class WebMediaPlayerImpl
   scoped_ptr<media::TextTrack> OnTextTrack(media::TextKind kind,
                                            const std::string& label,
                                            const std::string& language);
+  void OnFFmpegTextTrack(media::TextKind kind,

[acolwell GONE FROM CHROMIUM, 2013/09/12 00:15:15]

A separate method should not be needed for FFmpegDemuxer vs ChunkDemuxer. This
code should not be aware of the difference.

[Matthew Heaney (Chromium), 2013/09/13 19:51:54]

Agreed.  I'm thinking I should make the DemuxerHost changes first, and then when
that's working, change the ChunkDemuxer to use that too.

[Matthew Heaney (Chromium), 2013/09/20 23:53:54]

I haven't touched the ChunkDemuxer yet.  I just wanted to make sure I had the
threading model correct first.  Assuming it's correct, I can either fix the
ChunkDemuxer in a separate patch for this CL, or defer the change to a future
CL.

+                         const std::string& label,
+                         const std::string& language,
+                         int index);
   void SetOpaque(bool);
 
  private:
@@ -258,6 +264,11 @@ class WebMediaPlayerImpl
   // painted.
   void FrameReady(const scoped_refptr<media::VideoFrame>& frame);
 
+  // Called by TextRendererImpl when a decoded cue has been delivered on the
+  // text stream having the given |index|, and hence can be added to the
+  // cue list for this text track.
+  void CueReady(int index, const scoped_refptr<media::TextBuffer>& cue);
+
   WebKit::WebFrame* frame_;
 
   // TODO(hclam): get rid of these members and read from the pipeline directly.
@@ -367,6 +378,10 @@ class WebMediaPlayerImpl
   // Text track objects get a unique index value when they're created.
   int text_track_index_;
 
+  // Text track objects for the FFmpeg-based pipeline.
+  typedef std::map<int, media::TextTrack*> TextTrackMap;
+  TextTrackMap ffmpeg_text_track_map_;

[acolwell GONE FROM CHROMIUM, 2013/09/12 00:15:15]

The ChunkDemuxer didn't need this map here. Why does the FFmpeg code need it?

[Matthew Heaney (Chromium), 2013/09/13 19:51:54]

I was having some trouble getting the callback mechanism working (I'm still
learning the threading model), and this was the solution that managed to get
working.  No surprise that it's not optimal.  I think this will go away as a
side effect of the DemuxerHost changes.

[Matthew Heaney (Chromium), 2013/09/20 23:53:54]

As it turns out, creating a TextTrack(Impl) object must be done on the main
thread (there's a check in WebMediaPlayerImpl::client()).  Text cues must also
be dispatched to the Blink on the main thread (there's a check deep inside
blink).  So I made the decision to just keep all knowledge of TextTrack(Impl)
objects in WebMediaPlayerImpl, so I left this map here.  (Though in this patch,
the key type did change from int to DemuxerStream.)

+
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };