Allow setting memory limits on media::DemuxerStream

media/base/demuxer_stream.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.
 
 #ifndef MEDIA_BASE_DEMUXER_STREAM_H_
 #define MEDIA_BASE_DEMUXER_STREAM_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "media/base/media_export.h"
@@ skipping 73 matching lines @@
   // A DemuxerStream that returns 'true' to this may return the 'kConfigChange'
   // status from a Read() call. In this case the client is expected to be
   // capable of taking appropriate action to handle config changes. Otherwise
   // audio_decoder_config() and video_decoder_config()'s return values are
   // guaranteed to remain constant, and the client may make optimizations based
   // on this.
   virtual bool SupportsConfigChanges() = 0;
 
   virtual VideoRotation video_rotation() = 0;
 
+  // Get the data buffer size, in bytes.

[wolenetz, 2015/06/12 21:31:57]

nit: s/size/size limit/

[servolk, 2015/06/16 01:30:51]

Done.

+  virtual int GetMemoryLimit() const;

[wolenetz, 2015/06/12 21:31:56]

nit: signed int: is a range including negative values useful for this interface?

[servolk, 2015/06/16 01:30:51]

The best type for this is probably size_t, but the old
ChunkDemuxer::SetMemoryLimit API used ints for some reason. I assumed it was for
easier interoperability with blink and/or JS or perhaps negative values were
used to indicate something (seems not to be the case, but I didn't know that
when I started working on this CL).
I'll change the type to size_t and see if any issues pop up.

+
+  // Set the data buffer size, in bytes.

[wolenetz, 2015/06/12 21:31:56]

nit ditto (limit)

[servolk, 2015/06/16 01:30:51]

Done.

+  virtual void SetMemoryLimit(int memory_limit);

[wolenetz, 2015/06/12 21:31:56]

nit ditto (int ?)

Also, is a DemuxerStream valid if SetMemoryLimit() has never been called? If
not, should there be some default or ctor arg?
IOW, if the goal is to eventually have memory limit specified and observed for
all real DemuxerStream implementations, would some default not be known at ctor
time? If so, making such default a base class DemuxerStream ctor arg seems good
to me. Somewhat of a nit, not too strong a feeling on this one. WDYT?

[servolk, 2015/06/16 01:30:51]

Yes, there are reasonable defaults for memory limits
(kSourceBufferAudioMemoryLimit=12Mb/kSourceBufferVideoMemoryLimit=150Mb). So we
can get away without having to pass those in the constructor, having default
values is convenient and doesn't limit our flexibility, since we now provide a
mechanism to change those defaults.

+
  protected:
   // Only allow concrete implementations to get deleted.
   virtual ~DemuxerStream();
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_DEMUXER_STREAM_H_