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    // Signals an error has occurred.
32    virtual void OnRenderError() = 0;
33
34   protected:
35    virtual ~RenderCallback() {}
36  };
37
38  // Sets important information about the audio stream format.
39  // It must be called before any of the other methods.
40  virtual void Initialize(const AudioParameters& params,
41                          RenderCallback* callback) = 0;
42
43  // Starts audio playback.
44  virtual void Start() = 0;
45
46  // Stops audio playback.
47  virtual void Stop() = 0;
48
49  // Pauses playback.
50  virtual void Pause() = 0;
51
52  // Resumes playback after calling Pause().
53  virtual void Play() = 0;
54
55  // Sets the playback volume, with range [0.0, 1.0] inclusive.
56  // Returns |true| on success.
57  virtual bool SetVolume(double volume) = 0;
58
59 protected:
60  friend class base::RefCountedThreadSafe<AudioRendererSink>;
61  virtual ~AudioRendererSink() {}
62};
63
64}  // namespace media
65
66#endif  // MEDIA_BASE_AUDIO_RENDERER_SINK_H_
67