device/bluetooth/bluetooth_audio_sink.h

   1 // Copyright 2014 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 DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
   6 #define DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
   7
   8 #include <stdint.h>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "base/callback.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "device/bluetooth/bluetooth_export.h"
  16
  17 namespace device {
  18
  19 // TODO(mcchou): Define a BluetoothAudioSink specific IOBuffer abstraction.
  20
  21 // BluetoothAudioSink represents a local A2DP audio sink where a remote device
  22 // can stream audio data. Once a BluetoothAudioSink is successfully registered,
  23 // user applications can obtain a pointer to a BluetoothAudioSink object via
  24 // the interface provided by BluetoothAdapter. The validity of a
  25 // BluetoothAudioSink depends on whether BluetoothAdapter is present and whether
  26 // it is powered.
  27 class DEVICE_BLUETOOTH_EXPORT BluetoothAudioSink
  28     : public base::RefCounted<BluetoothAudioSink> {
  29  public:
  30   // Possible values indicating the connection states between the
  31   // BluetoothAudioSink and the remote device.
  32   enum State {
  33     STATE_INVALID,  // BluetoothAdapter not presented or not powered.
  34     STATE_DISCONNECTED,  // Not connected.
  35     STATE_IDLE,  // Connected but not streaming.
  36     STATE_PENDING,  // Connected, streaming but not acquired.
  37     STATE_ACTIVE,  // Connected, streaming and acquired.
  38   };
  39
  40   // Possible types of error raised by Audio Sink object.
  41   enum ErrorCode {
  42     ERROR_UNSUPPORTED_PLATFORM,  // A2DP sink not supported on current platform.
  43     ERROR_INVALID_ADAPTER,  // BluetoothAdapter not present/powered.
  44     ERROR_NOT_REGISTERED,  // BluetoothAudioSink not registered.
  45     ERROR_NOT_UNREGISTERED,  // BluetoothAudioSink not unregistered.
  46   };
  47
  48   // Options to configure an A2DP audio sink.
  49   struct Options {
  50     Options();
  51     ~Options();
  52
  53     uint8_t codec;
  54     std::vector<uint8_t> capabilities;
  55   };
  56
  57   // Interface for observing changes from a BluetoothAudioSink.
  58   class Observer {
  59    public:
  60     virtual ~Observer() {}
  61
  62     // Called when the state of the BluetoothAudioSink object is changed.
  63     // |audio_sink| indicates the object being changed, and |state| indicates
  64     // the new state of that object.
  65     virtual void BluetoothAudioSinkStateChanged(
  66         BluetoothAudioSink* audio_sink,
  67         BluetoothAudioSink::State state) = 0;
  68
  69     // Called when the volume of the BluetoothAudioSink object is changed.
  70     // |audio_sink| indicates the object being changed, and |volume| indicates
  71     // the new volume level of that object.
  72     virtual void BluetoothAudioSinkVolumeChanged(
  73         BluetoothAudioSink* audio_sink,
  74         uint16_t volume) = 0;
  75
  76     // Called when there is audio data available. |audio_sink| indicates the
  77     // object being changed. |data| is the pointer to the audio data and |size|
  78     // is the number of bytes in |data|. |read_mtu| is the max size of the RTP
  79     // packet. This method provides the raw audio data which hasn't been
  80     // processed, so RTP assembling and SBC decoding need to be handled in order
  81     // to get PCM data.
  82     virtual void BluetoothAudioSinkDataAvailable(BluetoothAudioSink* audio_sink,
  83                                                  char* data,
  84                                                  size_t size,
  85                                                  uint16_t read_mtu) = 0;
  86   };
  87
  88   // The ErrorCallback is used for the methods that can fail in which case it
  89   // is called.
  90   typedef base::Callback<void(ErrorCode)> ErrorCallback;
  91
  92   // Possible volumes for media transport are 0-127, and 128 is used to
  93   // represent invalid volume.
  94   static const uint16_t kInvalidVolume;
  95
  96   // Unregisters the audio sink. An audio sink will unregister itself
  97   // automatically in its destructor, but calling Unregister is recommended,
  98   // since user applications can be notified of an error returned by the call.
  99   virtual void Unregister(const base::Closure& callback,
 100                           const ErrorCallback& error_callback) = 0;
 101
 102   // Adds and removes an observer for events on the BluetoothAudioSink object.
 103   // If monitoring multiple audio sinks, check the |audio_sink| parameter of
 104   // observer methods to determine which audio sink is issuing the event.
 105   virtual void AddObserver(Observer* observer) = 0;
 106   virtual void RemoveObserver(Observer* observer) = 0;
 107
 108   // Getters for state and volume.
 109   virtual State GetState() const = 0;
 110
 111   // Returns the current volume level of the audio sink. The valid volumes are
 112   // 0-127, and |kInvalidVolume| is returned instead if the volume is unknown.
 113   virtual uint16_t GetVolume() const = 0;
 114
 115  protected:
 116   friend class base::RefCounted<BluetoothAudioSink>;
 117   BluetoothAudioSink();
 118
 119   // The destructor invokes Unregister() to ensure the audio sink will be
 120   // unregistered even if the user applications fail to do so.
 121   virtual ~BluetoothAudioSink();
 122
 123  private:
 124   DISALLOW_COPY_AND_ASSIGN(BluetoothAudioSink);
 125 };
 126
 127 }  // namespace device
 128
 129 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_