Support for parsing encrypted WebM streams by src.

media/filters/ffmpeg_demuxer.h

Index: media/filters/ffmpeg_demuxer.h
diff --git a/media/filters/ffmpeg_demuxer.h b/media/filters/ffmpeg_demuxer.h
index 6097c6b4f31a665d685efc8175fb1ccb59ba6881..1f665e923d1781c4a289624340f5ffe0c06cf9e6 100644
--- a/media/filters/ffmpeg_demuxer.h
+++ b/media/filters/ffmpeg_demuxer.h
@@ -23,6 +23,7 @@
 #define MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 
 #include <deque>
+#include <string>
 #include <vector>
 
 #include "base/callback.h"
@@ -43,6 +44,11 @@ struct AVStream;
 
 namespace media {
 
+// A new potentially encrypted stream has been parsed.
+// First parameter - The initialization data associated with the stream.
+// Second parameter - Number of bytes of the initialization data.
+typedef base::Callback<bool(scoped_array<uint8>, int)> FFmpegNeedKeyCB;
+
 class FFmpegDemuxer;
 class FFmpegH264ToAnnexBBitstreamConverter;
 class ScopedPtrAVFreePacket;
@@ -92,6 +98,8 @@ class FFmpegDemuxerStream : public DemuxerStream {
   // Used to determine stream duration when it's not known ahead of time.
   base::TimeDelta GetElapsedTime() const;
 
+  void KeyAdded();
+
  protected:
   virtual ~FFmpegDemuxerStream();
 
@@ -128,6 +136,9 @@ class FFmpegDemuxerStream : public DemuxerStream {
 
   scoped_ptr<FFmpegH264ToAnnexBBitstreamConverter> bitstream_converter_;
 
+  bool need_decryption_key_;

[ddorwin, 2012/08/22 23:20:29]

Curious why the demuxer cares. It shouldn't be blocking.

[fgalligan1, 2012/08/23 02:39:11]

See the other comment. Also if we don't have the demuxer block I think we will
need to re-architect the demuxer decoder interface. I think the demuxer expects
the decoder will only have one buffer at a time.

[xhwang, 2012/08/23 19:04:53]

I am not quite sure what's the problem. But the DemuxerStream just give out a
buffer when Read() is called if it can, or hold the callback and try to get more
data until it can give a buffer out. It should not worry about if the decoder
can decrypt or not.

So in summary, when the demuxer found a key_id, it should fire NeedKey with the
key_id and forget it. Whenever Read() is called the demuxer should hand out a
frame (encrypted or not) and should not worry about if the decryptor can decrypt
it.

[fgalligan1, 2012/08/24 20:01:26]

Removed. With xhwang's change this will work now.

+  std::string enc_key_id_;

[ddorwin, 2012/08/22 23:20:29]

Why do we store the key ID as state? There can be multiple. This is specific to
WebM too. (I'm fine with only supporting WebM now, but we should try to name
appropriately from the start.)

[fgalligan1, 2012/08/23 02:39:11]

I'm using this to decide if to create a DecryptConfig. Renamed to
current_key_id_.

+
   // Used to synchronize access to |buffer_queue_|, |read_queue_|, and
   // |stopped_|. This is so other threads can get access to buffers that have
   // already been demuxed without having the demuxer thread sending the
@@ -141,7 +152,8 @@ class FFmpegDemuxerStream : public DemuxerStream {
 class MEDIA_EXPORT FFmpegDemuxer : public Demuxer, public FFmpegURLProtocol {
  public:
   FFmpegDemuxer(const scoped_refptr<base::MessageLoopProxy>& message_loop,
-                const scoped_refptr<DataSource>& data_source);
+                const scoped_refptr<DataSource>& data_source,
+                const FFmpegNeedKeyCB& need_key_cb);
 
   // Posts a task to perform additional demuxing.
   virtual void PostDemuxTask();
@@ -167,6 +179,9 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer, public FFmpegURLProtocol {
   // Provide access to FFmpegDemuxerStream.
   scoped_refptr<base::MessageLoopProxy> message_loop();
 
+  virtual void KeyAdded() OVERRIDE;
+  void NeedKey(const std::string& key_id);

[ddorwin, 2012/08/22 23:20:29]

Should this be public?

[fgalligan1, 2012/08/23 02:39:11]

This is called from FFmpegDemuxerStream.

+
   // Allow FFmpegDemuxerStream to notify us when there is updated information
   // about what buffered data is available.
   void NotifyBufferingChanged();
@@ -192,6 +207,8 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer, public FFmpegURLProtocol {
   // Carries out disabling the audio stream on the demuxer thread.
   void DisableAudioStreamTask();
 
+  void KeyAddedTask();
+
   // Returns true if any of the streams have pending reads.  Since we lazily
   // post a DemuxTask() for every read, we use this method to quickly terminate
   // the tasks if there is no work to do.
@@ -267,6 +284,8 @@ class MEDIA_EXPORT FFmpegDemuxer : public Demuxer, public FFmpegURLProtocol {
   // stream -- at this moment we definitely know duration.
   bool duration_known_;
 
+  FFmpegNeedKeyCB need_key_cb_;

[ddorwin, 2012/08/22 23:20:29]

const

[fgalligan1, 2012/08/23 02:39:11]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };