Adds a second vector of streams to FFmpegDemuxer to handle re-mapped audio/video streams.

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.
 //
@@ skipping 131 matching lines @@
   //
   // Safe to call on any thread.
   bool StreamsHavePendingReads();
 
   // FFmpeg context handle.
   scoped_ptr_malloc<AVFormatContext, ScopedPtrAVFree> format_context_;
 
   // Latest timestamp read on the demuxer thread.
   base::TimeDelta current_timestamp_;
 
-  // Vector of streams.
+  // 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.
   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_