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