FFmpegDemuxerStream::Read() now functions properly while stopped.

media/filters/ffmpeg_demuxer.h

 // Copyright (c) 2009 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 and shuts down its internal thread.  Reads from a
+// stopped FFmpegDemuxerStream will not be replied to.
 
 #ifndef MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 #define MEDIA_FILTERS_FFMPEG_DEMUXER_H_
 
 #include <deque>
 #include <vector>
 
 #include "base/lock.h"
 #include "base/thread.h"
 #include "base/waitable_event.h"
@@ skipping 27 matching lines @@
 
   // Returns true is this stream has pending reads, false otherwise.
   //
   // Safe to call on any thread.
   bool HasPendingReads();
 
   // Enqueues and takes ownership over the given AVPacket, returns the timestamp
   // of the enqueued packet.
   base::TimeDelta EnqueuePacket(AVPacket* packet);
 
-  // Signals to empty queue and mark next packet as discontinuous.
+  // Signals to empty the buffer queue and mark next packet as discontinuous.
   void FlushBuffers();
 
+  // Empties the queues and ignores any additional calls to Read().
+  void Stop();
+
   // Returns the duration of this stream.
   base::TimeDelta duration() { return duration_; }
 
   // DemuxerStream implementation.
   virtual const MediaFormat& media_format();
   virtual void Read(Callback1<Buffer*>::Type* read_callback);
 
   // AVStreamProvider implementation.
   virtual AVStream* GetAVStream() { return stream_; }
 
  protected:
   virtual void* QueryInterface(const char* interface_id);
 
  private:
   // Returns true if there are still pending reads.
   bool FulfillPendingReads();
 
   // Converts an FFmpeg stream timestamp into a base::TimeDelta.
   base::TimeDelta ConvertTimestamp(int64 timestamp);
 
   FFmpegDemuxer* demuxer_;
   AVStream* stream_;
   MediaFormat media_format_;
   base::TimeDelta duration_;
   bool discontinuous_;
+  bool stopped_;
 
   Lock lock_;
 
   typedef std::deque< scoped_refptr<Buffer> > BufferQueue;
   BufferQueue buffer_queue_;
 
   typedef std::deque<Callback1<Buffer*>::Type*> ReadQueue;
   ReadQueue read_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxerStream);
@@ skipping 29 matching lines @@
 
   // Carries out initialization on the demuxer thread.
   void InititalizeTask(DataSource* data_source);
 
   // Carries out a seek on the demuxer thread.
   void SeekTask(base::TimeDelta time);
 
   // Carries out demuxing and satisfying stream reads on the demuxer thread.
   void DemuxTask();
 
+  // Carries out stopping the demuxer streams on the demuxer thread.
+  void StopTask();
+
   // 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.
   //
-  // Safe to call on any thread.
+  // Must be called on the demuxer thread.
   bool StreamsHavePendingReads();
 
   // Signal all FFmpegDemuxerStream that the stream has ended.
+  //
+  // Must be called on the demuxer thread.
   void StreamHasEnded();
 
-  // Helper function to deep copy an AVPacket's data, size and timestamps.
-  // Returns NULL if a packet could not be cloned (i.e., out of memory).
-  AVPacket* ClonePacket(AVPacket* packet);
-
   // FFmpeg context handle.
   scoped_ptr_malloc<AVFormatContext, ScopedPtrAVFree> format_context_;
 
   // Latest timestamp read on the demuxer thread.
   base::TimeDelta current_timestamp_;
 
   // Two vector of streams:
   //   - |streams_| is indexed for the Demuxer interface GetStream(), which only
   //     contains supported streams and no NULL entries.
   //   - |packet_streams_| is indexed to mirror AVFormatContext when dealing
   //     with AVPackets returned from av_read_frame() and contain NULL entries
   //     representing unsupported streams where we throw away the data.
   //
   // Ownership is handled via reference counting.
+  //
+  // Once initialized, operations on FFmpegDemuxerStreams should be carried out
+  // on the demuxer thread.
   typedef std::vector< scoped_refptr<FFmpegDemuxerStream> > StreamVector;
   StreamVector streams_;
   StreamVector packet_streams_;
 
   // Thread handle.
   base::Thread thread_;
 
   DISALLOW_COPY_AND_ASSIGN(FFmpegDemuxer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_FFMPEG_DEMUXER_H_