Simplify AudioSplicer logic which slots buffers before or after a splice point.

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 "base/basictypes.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ skipping 71 matching lines @@
   void Stop(const base::Closure& closure);
 
   // Returns true if the decoder currently has the ability to decode and return
   // an Output.
   // TODO(rileya): Remove the need for this by refactoring Decoder queueing
   // behavior.
   bool CanReadWithoutStalling() const;
 
   // Allows callers to register for notification of splice buffers from the
   // demuxer.  I.e., DecoderBuffer::splice_timestamp() is not kNoTimestamp().
+  //
+  // The observer will be notified of all buffers with a splice_timestamp() and
+  // the first buffer after which has a splice_timestamp() of kNoTimestamp().

[wolenetz, 2014/04/17 18:24:03]

Clarification of my understanding: Is the intent here that SpliceObserverCB
(AudioRendererImpl::OnNewSpliceBuffer currently) is notified of each in sequence
of the splice timestamps for all pre-splice buffers followed by the
post-splice-buffer? Is the order of splice notification vs read_cb_ undocumented
here? (If so, nit: please add that documentation. My understanding is there
could be some decoder delay, but read_cb_ should be executed for the decoded
active splice buffer at some point in time *after* the associated
spliceobservercb was called. Is this correct? Could there be more than one
buffer's decoded contents passed to read_cb_ in the interim, and would the
renderer_impl take such into account?)

[DaleCurtis, 2014/04/17 20:03:18]

I'll fix the comment in StreamParserBuffer() to document this better.  The
documentation here is a statement of what will happen, not how splices are made.

Since the first post splice buffer happens after a config change, we don't need
to worry about any additional buffers in the queue when marking the end of pre
splice buffers.

   typedef base::Callback<void(base::TimeDelta)> SpliceObserverCB;
   void set_splice_observer(const SpliceObserverCB& splice_observer) {
     splice_observer_cb_ = splice_observer;
   }
 
   // Allows callers to register for notification of config changes; this is
   // called immediately after recieving the 'kConfigChanged' status from the
   // DemuxerStream, before any action is taken to handle the config change.
   typedef base::Closure ConfigChangeObserverCB;
   void set_config_change_observer(
@@ skipping 71 matching lines @@
 
   scoped_ptr<DecoderSelector<StreamType> > decoder_selector_;
 
   // These two will be set by DecoderSelector::SelectDecoder().
   scoped_ptr<Decoder> decoder_;
   scoped_ptr<DecryptingDemuxerStream> decrypting_demuxer_stream_;
 
   SpliceObserverCB splice_observer_cb_;
   ConfigChangeObserverCB config_change_observer_cb_;
 
+  // If a splice_timestamp() has been seen, this is true until a
+  // splice_timestamp() of kNoTimestamp() is encountered.
+  bool active_splice_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<DecoderStream<StreamType> > weak_factory_;
 
   // This is required so the VideoFrameStream can access private members in
   // FinishInitialization() and ReportStatistics().
   DISALLOW_IMPLICIT_CONSTRUCTORS(DecoderStream);
 };
 
 template <>
 bool DecoderStream<DemuxerStream::AUDIO>::CanReadWithoutStalling() const;
 
 typedef DecoderStream<DemuxerStream::VIDEO> VideoFrameStream;
 typedef DecoderStream<DemuxerStream::AUDIO> AudioBufferStream;
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_DECODER_STREAM_H_