Simplified AudioOutputStream interface.

media/audio/audio_io.h

 // Copyright (c) 2010 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_AUDIO_AUDIO_IO_H_
 #define MEDIA_AUDIO_AUDIO_IO_H_
 
 #include "base/basictypes.h"
 #include "media/audio/audio_buffers_state.h"
 
@@ skipping 42 matching lines @@
     // Provide more data by filling |dest| up to |max_size| bytes. The provided
     // buffer size is usually what is specified in Open(). The source
     // will return the number of bytes it filled. The expected structure of
     // |dest| is platform and format specific.
     // |pending_bytes| is the number of bytes will be played before the
     // requested data is played.
     virtual uint32 OnMoreData(
         AudioOutputStream* stream, uint8* dest, uint32 max_size,
         AudioBuffersState buffers_state) = 0;
 
-    // The stream is done with this callback. After this call the audio source
-    // can go away or be destroyed.
-    virtual void OnClose(AudioOutputStream* stream) = 0;
-
     // There was an error while playing a buffer. Audio source cannot be
     // destroyed yet. No direct action needed by the AudioStream, but it is
     // a good place to stop accumulating sound data since is is likely that
     // playback will not continue. |code| is an error code that is platform
     // specific.
     virtual void OnError(AudioOutputStream* stream, int code) = 0;
   };
 
-  // Open the stream. |packet_size| is the requested buffer allocation which
-  // the audio source thinks it can usually fill without blocking. Internally
-  // two or three buffers of |packet_size| size are created, one will be
-  // locked for playback and one will be ready to be filled in the call to
-  // AudioSourceCallback::OnMoreData().
-  // The number of buffers is controlled by AUDIO_PCM_LOW_LATENCY. See more
-  // information below.
-  //
-  // TODO(ajwong): Streams are not reusable, so try to move packet_size into the
-  // constructor.
-  virtual bool Open(uint32 packet_size) = 0;
+  // Open the stream.

[scherkus (not reviewing), 2010/11/09 02:28:31]

so a lot of the comments went away

does it not apply anymore or can we at least be a bit more descriptive here? 
what does returning true/false mean? etc

[Sergey Ulanov, 2010/11/09 22:29:58]

The comments about |packet_size| do not apply anymore because we don't have this
parameter. The paragraph about AUDIO_PCM_LOW_LATENCY was invalid because it was
true only for Windows, on mac and linux you can't create stream with
AUDIO_PCM_LOW_LATENCY (BTW, do we need AUDIO_PCM_LOW_LATENCY at all? It doesn't
seem to be used anywhere)
I've added more comments here and above.

+  virtual bool Open() = 0;
 
   // Starts playing audio and generating AudioSourceCallback::OnMoreData().
   // Since implementor of AudioOutputStream may have internal buffers, right
   // after calling this method initial buffers are fetched.
   //
   // The output stream does not take ownership of this callback.
   virtual void Start(AudioSourceCallback* callback) = 0;
 
   // Stops playing audio. Effect might not be instantaneous as the hardware
   // might have locked audio data that is processing.
@@ skipping 53 matching lines @@
 
   // Close the stream. This also generates AudioInputCallback::OnClose(). This
   // should be the last call made on this object.
   virtual void Close() = 0;
 
  protected:
   virtual ~AudioInputStream() {}
 };
 
 #endif  // MEDIA_AUDIO_AUDIO_IO_H_