Allow audio system to handle synchronized low-latency audio I/O

media/audio/audio_io.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_AUDIO_AUDIO_IO_H_
 #define MEDIA_AUDIO_AUDIO_IO_H_
 
 #include "base/basictypes.h"
 #include "media/audio/audio_buffers_state.h"
 #include "media/base/audio_bus.h"
@@ skipping 39 matching lines @@
 namespace media {
 
 class MEDIA_EXPORT AudioOutputStream {
  public:
   // Audio sources must implement AudioSourceCallback. This interface will be
   // called in a random thread which very likely is a high priority thread. Do
   // not rely on using this thread TLS or make calls that alter the thread
   // itself such as creating Windows or initializing COM.
   class MEDIA_EXPORT AudioSourceCallback {
    public:
-    // Provide more data by fully filling |audio_bus|.  The source will return
+    // Provide more data by fully filling |dest|.  The source will return
     // the number of frames it filled.  |buffers_state| contains current state
     // of the buffers, and can be used by the source to calculate delay.
-    virtual int OnMoreData(AudioBus* audio_bus,
+    virtual int OnMoreData(AudioBus* dest,
                            AudioBuffersState buffers_state) = 0;
 
+    virtual int OnMoreIOData(AudioBus* source,
+                             AudioBus* dest,
+                             AudioBuffersState buffers_state) = 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;
 
     // Waits till data becomes available. Used when buffering data starting
     // new audio stream.
     // Polling is not the best approach, but incorporating messaging loop
@@ skipping 94 matching lines @@
   // Sets the Automatic Gain Control (AGC) state.
   virtual void SetAutomaticGainControl(bool enabled) = 0;
 
   // Returns the Automatic Gain Control (AGC) state.
   virtual bool GetAutomaticGainControl() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_IO_H_