media/audio/audio_output_ipc.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_AUDIO_AUDIO_OUTPUT_IPC_H_
   6 #define MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_
   7
   8 #include "base/memory/shared_memory.h"
   9 #include "base/sync_socket.h"
  10 #include "media/audio/audio_parameters.h"
  11 #include "media/base/media_export.h"
  12
  13 namespace media {
  14
  15 // Contains IPC notifications for the state of the server side
  16 // (AudioOutputController) audio state changes and when an AudioOutputController
  17 // has been created.  Implemented by AudioOutputDevice.
  18 class MEDIA_EXPORT AudioOutputIPCDelegate {
  19  public:
  20   // Current status of the audio output stream in the browser process. Browser
  21   // sends information about the current playback state and error to the
  22   // renderer process using this type.
  23   enum State {
  24     kPlaying,
  25     kPaused,
  26     kError
  27   };
  28
  29   // Called when state of an audio stream has changed.
  30   virtual void OnStateChanged(State state) = 0;
  31
  32   // Called when an audio stream has been created.
  33   // The shared memory |handle| points to a memory section that's used to
  34   // transfer audio buffers from the AudioOutputIPCDelegate back to the
  35   // AudioRendererHost.  The implementation of OnStreamCreated takes ownership.
  36   // The |socket_handle| is used by AudioRendererHost to signal requests for
  37   // audio data to be written into the shared memory. The AudioOutputIPCDelegate
  38   // must read from this socket and provide audio whenever data (search for
  39   // "pending_bytes") is received.
  40   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
  41                                base::SyncSocket::Handle socket_handle,
  42                                int length) = 0;
  43
  44   // Called when the AudioOutputIPC object is going away and/or when the IPC
  45   // channel has been closed and no more ipc requests can be made.
  46   // Implementations should delete their owned AudioOutputIPC instance
  47   // immediately.
  48   virtual void OnIPCClosed() = 0;
  49
  50  protected:
  51   virtual ~AudioOutputIPCDelegate();
  52 };
  53
  54 // Provides the IPC functionality for an AudioOutputIPCDelegate (e.g., an
  55 // AudioOutputDevice).  The implementation should asynchronously deliver the
  56 // messages to an AudioOutputController object (or create one in the case of
  57 // CreateStream()), that may live in a separate process.
  58 class MEDIA_EXPORT AudioOutputIPC {
  59  public:
  60   virtual ~AudioOutputIPC();
  61
  62   // Sends a request to create an AudioOutputController object in the peer
  63   // process and configures it to use the specified audio |params| including
  64   // number of synchronized input channels.|session_id| is used by the browser
  65   // to select the correct input device if the input channel in |params| is
  66   // valid, otherwise it will be ignored.  Once the stream has been created,
  67   // the implementation will notify |delegate| by calling OnStreamCreated().
  68   virtual void CreateStream(AudioOutputIPCDelegate* delegate,
  69                             const AudioParameters& params,
  70                             int session_id) = 0;
  71
  72   // Starts playing the stream.  This should generate a call to
  73   // AudioOutputController::Play().
  74   virtual void PlayStream() = 0;
  75
  76   // Pauses an audio stream.  This should generate a call to
  77   // AudioOutputController::Pause().
  78   virtual void PauseStream() = 0;
  79
  80   // Closes the audio stream which should shut down the corresponding
  81   // AudioOutputController in the peer process.
  82   virtual void CloseStream() = 0;
  83
  84   // Sets the volume of the audio stream.
  85   virtual void SetVolume(double volume) = 0;
  86 };
  87
  88 }  // namespace media
  89
  90 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_IPC_H_