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 "url/gurl.h"
  20
  21 namespace base {
  22 class SingleThreadTaskRunner;
  23 }
  24
  25 namespace media {
  26
  27 typedef base::Callback<void(SwitchOutputDeviceResult)> SwitchOutputDeviceCB;
  28
  29 // AudioRendererSink is an interface representing the end-point for
  30 // rendered audio.  An implementation is expected to
  31 // periodically call Render() on a callback object.
  32
  33 class AudioRendererSink
  34     : public base::RefCountedThreadSafe<media::AudioRendererSink> {
  35  public:
  36   class RenderCallback {
  37    public:
  38     // Attempts to completely fill all channels of |dest|, returns actual
  39     // number of frames filled.
  40     virtual int Render(AudioBus* dest, int audio_delay_milliseconds) = 0;
  41
  42     // Signals an error has occurred.
  43     virtual void OnRenderError() = 0;
  44
  45    protected:
  46     virtual ~RenderCallback() {}
  47   };
  48
  49   // Sets important information about the audio stream format.
  50   // It must be called before any of the other methods.
  51   virtual void Initialize(const AudioParameters& params,
  52                           RenderCallback* callback) = 0;
  53
  54   // Starts audio playback.
  55   virtual void Start() = 0;
  56
  57   // Stops audio playback.
  58   virtual void Stop() = 0;
  59
  60   // Pauses playback.
  61   virtual void Pause() = 0;
  62
  63   // Resumes playback after calling Pause().
  64   virtual void Play() = 0;
  65
  66   // Sets the playback volume, with range [0.0, 1.0] inclusive.
  67   // Returns |true| on success.
  68   virtual bool SetVolume(double volume) = 0;
  69
  70   // Attempts to switch the audio output device.
  71   // Once the attempt is finished, |callback| is invoked with the
  72   // result of the operation passed as a parameter. The result is a value from
  73   // the  media::SwitchOutputDeviceResult enum.
  74   // There is no guarantee about the thread where |callback| will
  75   // be invoked, so users are advised to use media::BindToCurrentLoop() to
  76   // ensure that |callback| runs on the correct thread.
  77   // Note also that copy constructors and destructors for arguments bound to
  78   // |callback| may run on arbitrary threads as |callback| is moved across
  79   // threads. It is advisable to bind arguments such that they are released by
  80   // |callback| when it runs in order to avoid surprises.
  81   virtual void SwitchOutputDevice(const std::string& device_id,
  82                                   const GURL& security_origin,
  83                                   const SwitchOutputDeviceCB& callback) = 0;
  84
  85  protected:
  86   friend class base::RefCountedThreadSafe<AudioRendererSink>;
  87   virtual ~AudioRendererSink() {}
  88 };
  89
  90 }  // namespace media
  91
  92 #endif  // MEDIA_BASE_AUDIO_RENDERER_SINK_H_