media/base/audio_renderer_sink.h

   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 <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/callback.h"
  13 #include "base/logging.h"
  14 #include "base/memory/ref_counted.h"
  15 #include "media/audio/audio_output_ipc.h"
  16 #include "media/audio/audio_parameters.h"
  17 #include "media/base/audio_bus.h"
  18 #include "media/base/media_export.h"
  19 #include "media/base/output_device.h"
  20 #include "url/gurl.h"
  21
  22 namespace base {
  23 class SingleThreadTaskRunner;
  24 }
  25
  26 namespace media {
  27
  28 // AudioRendererSink is an interface representing the end-point for
  29 // rendered audio.  An implementation is expected to
  30 // periodically call Render() on a callback object.
  31
  32 class AudioRendererSink
  33     : public base::RefCountedThreadSafe<media::AudioRendererSink> {
  34  public:
  35   class RenderCallback {
  36    public:
  37     // Attempts to completely fill all channels of |dest|, returns actual
  38     // number of frames filled.
  39     virtual int Render(AudioBus* dest, int audio_delay_milliseconds) = 0;
  40
  41     // Signals an error has occurred.
  42     virtual void OnRenderError() = 0;
  43
  44    protected:
  45     virtual ~RenderCallback() {}
  46   };
  47
  48   // Sets important information about the audio stream format.
  49   // It must be called before any of the other methods.
  50   virtual void Initialize(const AudioParameters& params,
  51                           RenderCallback* callback) = 0;
  52
  53   // Starts audio playback.
  54   virtual void Start() = 0;
  55
  56   // Stops audio playback.
  57   virtual void Stop() = 0;
  58
  59   // Pauses playback.
  60   virtual void Pause() = 0;
  61
  62   // Resumes playback after calling Pause().
  63   virtual void Play() = 0;
  64
  65   // Sets the playback volume, with range [0.0, 1.0] inclusive.
  66   // Returns |true| on success.
  67   virtual bool SetVolume(double volume) = 0;
  68
  69   // Returns a pointer to the internal output device.
  70   // This pointer is not to be owned by the caller and is valid only during
  71   // the lifetime of the AudioRendererSink.
  72   // It can be null, which means that access to the output device is not
  73   // supported.
  74   virtual OutputDevice* GetOutputDevice() = 0;
  75
  76  protected:
  77   friend class base::RefCountedThreadSafe<AudioRendererSink>;
  78   virtual ~AudioRendererSink() {}
  79 };
  80
  81 }  // namespace media
  82
  83 #endif  // MEDIA_BASE_AUDIO_RENDERER_SINK_H_