root/media/audio/audio_input_ipc.h

INCLUDED FROM

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_AUDIO_INPUT_IPC_H_
#define MEDIA_AUDIO_AUDIO_INPUT_IPC_H_

#include "base/memory/shared_memory.h"
#include "base/sync_socket.h"
#include "media/audio/audio_parameters.h"
#include "media/base/media_export.h"

namespace media {

// Contains IPC notifications for the state of the server side
// (AudioInputController) audio state changes and when an AudioInputController
// has been created.  Implemented by AudioInputDevice.
class MEDIA_EXPORT AudioInputIPCDelegate {
 public:
  // Valid states for the input stream.
  enum State {
    kRecording,
    kStopped,
    kError,
    kStateLast = kError
  };

  // Called when an AudioInputController has been created.
  // The shared memory |handle| points to a memory section that's used to
  // transfer data between the AudioInputDevice and AudioInputController
  // objects.  The implementation of OnStreamCreated takes ownership.
  // The |socket_handle| is used by the AudioInputController to signal
  // notifications that more data is available and can optionally provide
  // parameter changes back.  The AudioInputDevice must read from this socket
  // and process the shared memory whenever data is read from the socket.
  virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                               base::SyncSocket::Handle socket_handle,
                               int length,
                               int total_segments) = 0;

  // Called when state of an audio stream has changed.
  virtual void OnStateChanged(State state) = 0;

  // Called when the input stream volume has changed.
  virtual void OnVolume(double volume) = 0;

  // Called when the AudioInputIPC object is going away and/or when the
  // IPC channel has been closed and no more IPC requests can be made.
  // Implementations should delete their owned AudioInputIPC instance
  // immediately.
  virtual void OnIPCClosed() = 0;

 protected:
  virtual ~AudioInputIPCDelegate();
};

// Provides IPC functionality for an AudioInputIPCDelegate (e.g., an
// AudioInputDevice).  The implementation should asynchronously deliver the
// messages to an AudioInputController object (or create one in the case of
// CreateStream()), that may live in a separate process.
class MEDIA_EXPORT AudioInputIPC {
 public:
  virtual ~AudioInputIPC();

  // Sends a request to create an AudioInputController object in the peer
  // process, and configures it to use the specified audio |params|.  The
  // |total_segments| indidates number of equal-lengthed segments in the shared
  // memory buffer.  Once the stream has been created, the implementation will
  // notify |delegate| by calling OnStreamCreated().
  virtual void CreateStream(AudioInputIPCDelegate* delegate,
                            int session_id,
                            const AudioParameters& params,
                            bool automatic_gain_control,
                            uint32 total_segments) = 0;

  // Corresponds to a call to AudioInputController::Record() on the server side.
  virtual void RecordStream() = 0;

  // Sets the volume of the audio stream.
  virtual void SetVolume(double volume) = 0;

  // Closes the audio stream, which should shut down the corresponding
  // AudioInputController in the peer process.
  virtual void CloseStream() = 0;
};

}  // namespace media

#endif  // MEDIA_AUDIO_AUDIO_INPUT_IPC_H_