Support for parsing encrypted WebM streams by src.

media/filters/ffmpeg_demuxer.h

 // 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.
 
 // Implements the Demuxer interface using FFmpeg's libavformat.  At this time
 // will support demuxing any audio/video format thrown at it.  The streams
 // output mime types audio/x-ffmpeg and video/x-ffmpeg and include an integer
 // key FFmpegCodecID which contains the CodecID enumeration value.  The CodecIDs
 // can be used to create and initialize the corresponding FFmpeg decoder.
 //
 // FFmpegDemuxer sets the duration of pipeline during initialization by using
 // the duration of the longest audio/video stream.
 //
 // NOTE: since FFmpegDemuxer reads packets sequentially without seeking, media
 // files with very large drift between audio/video streams may result in
 // excessive memory consumption.
 //
 // When stopped, FFmpegDemuxer and FFmpegDemuxerStream release all callbacks
 // and buffered packets.  Reads from a stopped FFmpegDemuxerStream will not be
 // replied to.
 
 #ifndef MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 #define MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 
+#include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
 #include "base/threading/thread.h"
 #include "media/base/audio_decoder_config.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decoder_buffer_queue.h"
 #include "media/base/demuxer.h"
 #include "media/base/pipeline.h"
 #include "media/base/video_decoder_config.h"
 #include "media/filters/blocking_url_protocol.h"
 
 // FFmpeg forward declarations.
 struct AVPacket;
 struct AVRational;
 struct AVStream;
 
 namespace media {
 
+// A new potentially encrypted stream has been parsed.
+// First parameter - The type of encryption.

[ddorwin, 2013/03/10 21:29:39]

s/encryption/initialization data/

[fgalligan1, 2013/03/12 00:42:42]

Done.

+// Second parameter - The initialization data associated with the stream.
+// Third parameter - Number of bytes of the initialization data.
+typedef base::Callback<void(const std::string& type,
+                            scoped_array<uint8> init_data,
+                            int init_data_size)> FFmpegNeedKeyCB;
+
 class FFmpegDemuxer;
 class FFmpegGlue;
 class FFmpegH264ToAnnexBBitstreamConverter;
 class ScopedPtrAVFreePacket;
 
 typedef scoped_ptr_malloc<AVPacket, ScopedPtrAVFreePacket> ScopedAVPacket;
 
 class FFmpegDemuxerStream : public DemuxerStream {
  public:
   // Keeps a copy of |demuxer| and initializes itself using information
@@ skipping 59 matching lines @@
   bool end_of_stream_;
   base::TimeDelta last_packet_timestamp_;
   Ranges<base::TimeDelta> buffered_ranges_;
 
   DecoderBufferQueue buffer_queue_;
   ReadCB read_cb_;
 
   scoped_ptr<FFmpegH264ToAnnexBBitstreamConverter> bitstream_converter_;
   bool bitstream_converter_enabled_;
 
+  std::string audio_encryption_key_id_;

[ddorwin, 2013/03/10 21:29:39]

A demuxer stream only supports audio or video, right? So we only need
encryption_key_id_.

[fgalligan1, 2013/03/12 00:42:42]

Done.

+  std::string video_encryption_key_id_;
+
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
 };
 
 class MEDIA_EXPORT FFmpegDemuxer : public Demuxer {
  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);
 
   // Demuxer implementation.
   virtual void Initialize(DemuxerHost* host,
                           const PipelineStatusCB& status_cb) OVERRIDE;
   virtual void Stop(const base::Closure& callback) OVERRIDE;
   virtual void Seek(base::TimeDelta time, const PipelineStatusCB& cb) OVERRIDE;
   virtual void OnAudioRendererDisabled() OVERRIDE;
   virtual void SetPlaybackRate(float playback_rate) OVERRIDE;
   virtual scoped_refptr<DemuxerStream> GetStream(
       DemuxerStream::Type type) OVERRIDE;
   virtual base::TimeDelta GetStartTime() const OVERRIDE;
 
+  // Calls |need_key_cb_| with the encryption key id of the decryption key

[ddorwin, 2013/03/10 21:29:39]

// Calls |need_key_cb_| with the initialization data encountered in the file.
?

[fgalligan1, 2013/03/12 00:42:42]

Done. I agree.

+  // that is needed.
+  void FireNeedKey(const std::string& init_data_type,
+                   const std::string& encryption_key_id);
+
   // Allow FFmpegDemuxerStream to notify us when there is updated information
   // about capacity and what buffered data is available.
   void NotifyCapacityAvailable();
   void NotifyBufferingChanged();
 
  private:
   // To allow tests access to privates.
   friend class FFmpegDemuxerTest;
 
   virtual ~FFmpegDemuxer();
@@ skipping 73 matching lines @@
   bool audio_disabled_;
 
   // Set if we know duration of the audio stream. Used when processing end of
   // stream -- at this moment we definitely know duration.
   bool duration_known_;
 
   // FFmpegURLProtocol implementation and corresponding glue bits.
   BlockingUrlProtocol url_protocol_;
   scoped_ptr<FFmpegGlue> glue_;
 
+  const FFmpegNeedKeyCB need_key_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_