gecko/content/media/omx/AudioOutput.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/*
 * Copyright (c) 2014 The Linux Foundation. All rights reserved.
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef AUDIOOUTPUT_H_
#define AUDIOOUTPUT_H_

#include <stagefright/foundation/ABase.h>
#include <utils/Mutex.h>
#include <AudioTrack.h>

#include "AudioSink.h"

#define LOG_TAG "AudioOffloadPlayer"

namespace mozilla {

/**
 * Stripped version of Android KK MediaPlayerService::AudioOutput class
 * Android MediaPlayer uses AudioOutput as a wrapper to handle
 * Android::AudioTrack
 * Similarly to ease handling offloaded tracks, part of AudioOutput is used here
 */
class AudioOutput : public AudioSink
{
  typedef android::Mutex Mutex;
  typedef android::String8 String8;
  typedef android::status_t status_t;
  typedef android::AudioTrack AudioTrack;

  class CallbackData;

public:
  AudioOutput(int aSessionId, int aUid);
  virtual ~AudioOutput();

  virtual ssize_t FrameSize() const;
  virtual status_t GetPosition(uint32_t* aPosition) const;
  virtual status_t SetVolume(float aVolume) const;
  virtual status_t SetParameters(const String8& aKeyValuePairs);

  // Creates an offloaded audio track with the given parameters
  // TODO: Try to recycle audio tracks instead of creating new audio tracks
  // every time
  virtual status_t Open(uint32_t aSampleRate,
                        int aChannelCount,
                        audio_channel_mask_t aChannelMask,
                        audio_format_t aFormat,
                        AudioCallback aCb,
                        void* aCookie,
                        audio_output_flags_t aFlags = AUDIO_OUTPUT_FLAG_NONE,
                        const audio_offload_info_t* aOffloadInfo = nullptr);

  virtual status_t Start();
  virtual void Stop();
  virtual void Flush();
  virtual void Pause();
  virtual void Close();

private:
  static void CallbackWrapper(int aEvent, void* aMe, void* aInfo);

  android::sp<AudioTrack> mTrack;
  void* mCallbackCookie;
  AudioCallback mCallback;
  CallbackData* mCallbackData;

  // Uid of the current process, need to create audio track
  int mUid;

  // Session id given by Android::AudioSystem and used to create audio track
  int mSessionId;

  // CallbackData is what is passed to the AudioTrack as the "user" data.
  // We need to be able to target this to a different Output on the fly,
  // so we can't use the Output itself for this.
  class CallbackData
  {
    public:
      CallbackData(AudioOutput* aCookie)
      {
        mData = aCookie;
      }
      AudioOutput* GetOutput() { return mData;}
      void SetOutput(AudioOutput* aNewcookie) { mData = aNewcookie; }
      // Lock/Unlock are used by the callback before accessing the payload of
      // this object
      void Lock() { mLock.lock(); }
      void Unlock() { mLock.unlock(); }
    private:
      AudioOutput* mData;
      mutable Mutex mLock;
      DISALLOW_EVIL_CONSTRUCTORS(CallbackData);
  };
}; // AudioOutput

} // namespace mozilla

#endif /* AUDIOOUTPUT_H_ */