audio_renderer_sink.h revision 868fa2fe829687343ffae624259930155e16dbd8 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef MEDIA_BASE_AUDIO_RENDERER_SINK_H_
6#define MEDIA_BASE_AUDIO_RENDERER_SINK_H_
7
8#include <vector>
9#include "base/basictypes.h"
10#include "base/logging.h"
11#include "base/memory/ref_counted.h"
12#include "media/audio/audio_parameters.h"
13#include "media/base/audio_bus.h"
14#include "media/base/media_export.h"
15
16namespace media {
17
18// AudioRendererSink is an interface representing the end-point for
19// rendered audio.  An implementation is expected to
20// periodically call Render() on a callback object.
21
22class AudioRendererSink
23    : public base::RefCountedThreadSafe<media::AudioRendererSink> {
24 public:
25  class RenderCallback {
26   public:
27    // Attempts to completely fill all channels of |dest|, returns actual
28    // number of frames filled.
29    virtual int Render(AudioBus* dest, int audio_delay_milliseconds) = 0;
30
31    // Synchronized audio I/O - see InitializeIO() below.
32    virtual void RenderIO(AudioBus* source,
33                          AudioBus* dest,
34                          int audio_delay_milliseconds) {}
35
36    // Signals an error has occurred.
37    virtual void OnRenderError() = 0;
38
39   protected:
40    virtual ~RenderCallback() {}
41  };
42
43  // Sets important information about the audio stream format.
44  // It must be called before any of the other methods.
45  virtual void Initialize(const AudioParameters& params,
46                          RenderCallback* callback) = 0;
47
48  // Starts audio playback.
49  virtual void Start() = 0;
50
51  // Stops audio playback.
52  virtual void Stop() = 0;
53
54  // Pauses playback.
55  virtual void Pause() = 0;
56
57  // Resumes playback after calling Pause().
58  virtual void Play() = 0;
59
60  // Sets the playback volume, with range [0.0, 1.0] inclusive.
61  // Returns |true| on success.
62  virtual bool SetVolume(double volume) = 0;
63
64 protected:
65  friend class base::RefCountedThreadSafe<AudioRendererSink>;
66  virtual ~AudioRendererSink() {}
67};
68
69}  // namespace media
70
71#endif  // MEDIA_BASE_AUDIO_RENDERER_SINK_H_
72