Very early implementation for HTMLMediaElement / Web Audio API integration

content/renderer/media/audio_device.h

 // Copyright (c) 2011 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.
 //
 // Low-latency audio rendering unit utilizing audio output stream provided
 // by browser process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioOutputController                AudioDevice
@@ skipping 39 matching lines @@
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "base/threading/simple_thread.h"
 #include "content/renderer/media/audio_message_filter.h"
 
 struct AudioParameters;
 
-class AudioDevice
-    : public AudioMessageFilter::Delegate,
-      public base::DelegateSimpleThread::Delegate,
-      public base::RefCountedThreadSafe<AudioDevice> {
+
+class AudioSink : public base::RefCountedThreadSafe<AudioSink> {

[scherkus (not reviewing), 2011/08/23 15:16:01]

what's the reasoning behind using an AudioSink as opposed to passing an
AudioDevice directly?

should also get moved to a separate .h file w/ docs

[Chris Rogers, 2011/08/24 00:41:52]

The idea is that there can be more than one kind of AudioSink:
1) AudioDevice which talks to the browser process
2) RenderAudioSourceProvider which connects into MediaElementAudioSourceNode
inside WebKit
3) ... maybe some other kind of destination for rendered audio stream in the
renderer ...

In this latest patch, I've renamed AudioSink to AudioRendererSink

On 2011/08/23 15:16:01, scherkus wrote:

  public:
   class RenderCallback {
    public:
     virtual void Render(const std::vector<float*>& audio_data,
                         size_t number_of_frames,
                         size_t audio_delay_milliseconds) = 0;
    protected:
     virtual ~RenderCallback() {}
   };
 
+  // Starts audio playback. Returns |true| on success.
+  virtual bool Start() = 0;
+
+    // Stops audio playback. Returns |true| on success.
+  virtual bool Stop() = 0;
+
+  // Sets the playback volume, with range [0.0, 1.0] inclusive.
+  // Returns |true| on success.
+  virtual bool SetVolume(double volume) = 0;
+};
+
+
+class AudioDevice
+    : public AudioMessageFilter::Delegate,
+      public base::DelegateSimpleThread::Delegate,
+      public AudioSink {
+ public:
+
   // Methods called on main render thread -------------------------------------
   AudioDevice(size_t buffer_size,
               int channels,
               double sample_rate,
               RenderCallback* callback);
   virtual ~AudioDevice();
 
   // Starts audio playback. Returns |true| on success.
   bool Start();

[scherkus (not reviewing), 2011/08/23 15:16:01]

Start/Stop/SetVolume() should become virtual and OVERRIDE

[Chris Rogers, 2011/08/24 00:41:52]

Done.

 
   // Stops audio playback. Returns |true| on success.
   bool Stop();
 
   // Sets the playback volume, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool SetVolume(double volume);
 
   // Gets the playback volume, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
@@ skipping 69 matching lines @@
 
   // Data transfer between browser and render process uses a combination
   // of sync sockets and shared memory to provide lowest possible latency.
   scoped_ptr<base::SharedMemory> shared_memory_;
   scoped_ptr<base::SyncSocket> socket_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_