Attempt decoder fallback if first decode fails

media/filters/decoder_stream.h

 // Copyright 2014 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.
 
 #ifndef MEDIA_FILTERS_DECODER_STREAM_H_
 #define MEDIA_FILTERS_DECODER_STREAM_H_
 
 #include <list>
 
 #include "base/callback.h"
@@ skipping 104 matching lines @@
   typedef base::Closure ConfigChangeObserverCB;
   void set_config_change_observer(
       const ConfigChangeObserverCB& config_change_observer) {
     config_change_observer_cb_ = config_change_observer;
   }
 
   const Decoder* get_previous_decoder_for_testing() const {
     return previous_decoder_.get();
   }
 
+  int get_pending_buffers_size_for_testing() const {
+    return pending_buffers_.size();
+  }
+
+  int get_fallback_buffers_size_for_testing() const {
+    return fallback_buffers_.size();
+  }
+
  private:
   enum State {
     STATE_UNINITIALIZED,
     STATE_INITIALIZING,
     STATE_NORMAL,  // Includes idle, pending decoder decode/reset.
     STATE_FLUSHING_DECODER,
     STATE_PENDING_DEMUXER_READ,
     STATE_REINITIALIZING_DECODER,
     STATE_END_OF_STREAM,  // End of stream reached; returns EOS on all reads.
-    STATE_ERROR
+    STATE_ERROR,
+    // TODO(tguilbert): support config changes during decoder fallback, see
+    // crbug.com/603713
+    STATE_CONFIG_CHANGE_RECEIVED_WHILE_REINITIALIZING_DECODER
   };
 
   void SelectDecoder(CdmContext* cdm_context);
 
   // Called when |decoder_selector| selected the |selected_decoder|.
   // |decrypting_demuxer_stream| was also populated if a DecryptingDemuxerStream
   // is created to help decrypt the encrypted stream.
   void OnDecoderSelected(
       scoped_ptr<Decoder> selected_decoder,
       scoped_ptr<DecryptingDemuxerStream> decrypting_demuxer_stream);
 
   // Satisfy pending |read_cb_| with |status| and |output|.
   void SatisfyRead(Status status,
                    const scoped_refptr<Output>& output);
 
   // Decodes |buffer| and returns the result via OnDecodeOutputReady().
+  // Saves |buffer| into |pending_buffers_| if appropriate.
   void Decode(const scoped_refptr<DecoderBuffer>& buffer);
 
+  // Performs the heavy lifting of the decode call.
+  void DecodeInternal(const scoped_refptr<DecoderBuffer>& buffer);
+
   // Flushes the decoder with an EOS buffer to retrieve internally buffered
   // decoder output.
   void FlushDecoder();
 
   // Callback for Decoder::Decode().
   void OnDecodeDone(int buffer_size, bool end_of_stream, DecodeStatus status);
 
   // Output callback passed to Decoder::Initialize().
   void OnDecodeOutputReady(const scoped_refptr<Output>& output);
 
@@ skipping 55 matching lines @@
   // Decoded buffers that haven't been read yet. Used when the decoder supports
   // parallel decoding.
   std::list<scoped_refptr<Output> > ready_outputs_;
 
   // Number of outstanding decode requests sent to the |decoder_|.
   int pending_decode_requests_;
 
   // Tracks the duration of incoming packets over time.
   MovingAverage duration_tracker_;
 
+  // Stores buffers that might be reused if the decoder fails right after
+  // Initialize().
+  std::deque<scoped_refptr<DecoderBuffer>> pending_buffers_;
+
+  // Stores buffers that are garanteed to be fed to the decoder before fetching

[DaleCurtis, 2016/04/15 01:19:17]

guaranteed 

[tguilbert, 2016/04/15 20:45:52]

Done.

+  // more from the demuxer stream. Populated by |pending_buffers_| on decoder

[DaleCurtis, 2016/04/15 01:19:17]

"Populated by ..." seems like it should be followed by a function name, not
another variable name?

[tguilbert, 2016/04/15 20:45:52]

Done.

+  // fallback.
+  std::deque<scoped_refptr<DecoderBuffer>> fallback_buffers_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
-  base::WeakPtrFactory<DecoderStream<StreamType> > weak_factory_;
+  base::WeakPtrFactory<DecoderStream<StreamType>> weak_factory_;
+  base::WeakPtrFactory<DecoderStream<StreamType>> decode_weak_factory_;

[DaleCurtis, 2016/04/15 01:19:17]

This should have a comment about exactly what this is for.

[tguilbert, 2016/04/15 20:45:52]

Done.

 };
 
 template <>
 bool DecoderStream<DemuxerStream::AUDIO>::CanReadWithoutStalling() const;
 
 template <>
 int DecoderStream<DemuxerStream::AUDIO>::GetMaxDecodeRequests() const;
 
 typedef DecoderStream<DemuxerStream::VIDEO> VideoFrameStream;
 typedef DecoderStream<DemuxerStream::AUDIO> AudioBufferStream;
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_DECODER_STREAM_H_