Integrate HTMLMediaElement with Web Audio API's MediaElementAudioSourceNode

media/filters/audio_renderer_sink.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.
+
+#ifndef MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_
+#define MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_
+
+#include <vector>
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "media/audio/audio_parameters.h"
+
+namespace media {
+
+// AudioRendererSink is an interface representing the end-point for
+// rendered audio in the renderer process.  An implementation is expected to
+// periodically call Render() on a callback object.  The normal implementation
+// will talk with the browser process to get a rendered audio stream to the
+// audio hardware.
+
+class AudioRendererSink
+    : public base::RefCountedThreadSafe<media::AudioRendererSink> {
+ public:
+  class RenderCallback {
+   public:
+    virtual void Render(const std::vector<float*>& audio_data,
+                        size_t number_of_frames,
+                        size_t audio_delay_milliseconds) = 0;
+
+    virtual void SetAudioRendererSink(media::AudioRendererSink* audio_sink) {}

[acolwell GONE FROM CHROMIUM, 2011/12/19 23:01:49]

I too believe this should be removed. Conceptually it seems strange to me to
pass an object to an AudioRendererSink with a method that is supposed to change
it's implementation. I can't quite put my finger on what to call it, but it
seems like breaking encapsulation.

[Chris Rogers, 2011/12/19 23:28:14]

That settles it!  I'm moving this directly into AudioRendererImpl (when we've
finished discussing your other comments)

On 2011/12/19 23:01:49, acolwell wrote:

[Chris Rogers, 2011/12/21 01:38:17]

Done.

+
+   protected:
+    virtual ~RenderCallback() {}
+  };
+
+  virtual ~AudioRendererSink() {}
+
+  // Sets important information about the audio stream format.
+  // It must be called before any of the other methods.
+  virtual void Initialize(size_t buffer_size,
+                          int channels,
+                          double sample_rate,
+                          AudioParameters::Format latency_format,
+                          RenderCallback* callback) = 0;
+
+  // Starts audio playback.
+  virtual void Start() = 0;
+
+  // Stops audio playback.
+  virtual void Stop() = 0;
+
+  // Pauses playback.
+  virtual void Pause(bool flush) = 0;
+
+  // Resumes playback after calling Pause().
+  virtual void Play() = 0;
+
+  // Sets the playback volume, with range [0.0, 1.0] inclusive.
+  // Returns |true| on success.
+  virtual bool SetVolume(double volume) = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_AUDIO_RENDERER_SINK_H_