gecko/content/media/nsAudioAvailableEventManager.cpp

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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
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 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla code.
 *
 * The Initial Developer of the Original Code is the Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  David Humphrey <david.humphrey@senecac.on.ca>
 *  Yury Delendik
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#include "nsTArray.h"
#include "nsAudioAvailableEventManager.h"

#define MILLISECONDS_PER_SECOND 1000.0f
#define MAX_PENDING_EVENTS 100

using namespace mozilla;

class nsAudioAvailableEventRunner : public nsRunnable
{
private:
  nsCOMPtr<nsBuiltinDecoder> mDecoder;
  nsAutoArrayPtr<float> mFrameBuffer;
public:
  nsAudioAvailableEventRunner(nsBuiltinDecoder* aDecoder, float* aFrameBuffer,
                              PRUint32 aFrameBufferLength, float aTime) :
    mDecoder(aDecoder),
    mFrameBuffer(aFrameBuffer),
    mFrameBufferLength(aFrameBufferLength),
    mTime(aTime)
  {
    MOZ_COUNT_CTOR(nsAudioAvailableEventRunner);
  }

  ~nsAudioAvailableEventRunner() {
    MOZ_COUNT_DTOR(nsAudioAvailableEventRunner);
  }

  NS_IMETHOD Run()
  {
    mDecoder->AudioAvailable(mFrameBuffer.forget(), mFrameBufferLength, mTime);
    return NS_OK;
  }

  const PRUint32 mFrameBufferLength;

  // Start time of the buffer data (in seconds).
  const float mTime;
};


nsAudioAvailableEventManager::nsAudioAvailableEventManager(nsBuiltinDecoder* aDecoder) :
  mDecoder(aDecoder),
  mSignalBuffer(new float[mDecoder->GetFrameBufferLength()]),
  mSignalBufferLength(mDecoder->GetFrameBufferLength()),
  mSignalBufferPosition(0),
  mMonitor("media.audioavailableeventmanager")
{
  MOZ_COUNT_CTOR(nsAudioAvailableEventManager);
}

nsAudioAvailableEventManager::~nsAudioAvailableEventManager()
{
  MOZ_COUNT_DTOR(nsAudioAvailableEventManager);
}

void nsAudioAvailableEventManager::Init(PRUint32 aChannels, PRUint32 aRate)
{
  NS_ASSERTION(aChannels != 0 && aRate != 0, "Audio metadata not known.");
  mSamplesPerSecond = static_cast<float>(aChannels * aRate);
}

void nsAudioAvailableEventManager::DispatchPendingEvents(PRUint64 aCurrentTime)
{
  MonitorAutoEnter mon(mMonitor);

  while (mPendingEvents.Length() > 0) {
    nsAudioAvailableEventRunner* e =
      (nsAudioAvailableEventRunner*)mPendingEvents[0].get();
    if (e->mTime * MILLISECONDS_PER_SECOND > aCurrentTime) {
      break;
    }
    nsCOMPtr<nsIRunnable> event = mPendingEvents[0];
    mPendingEvents.RemoveElementAt(0);
    NS_DispatchToMainThread(event, NS_DISPATCH_NORMAL);
  }
}

void nsAudioAvailableEventManager::QueueWrittenAudioData(SoundDataValue* aAudioData,
                                                         PRUint32 aAudioDataLength,
                                                         PRUint64 aEndTimeSampleOffset)
{
  PRUint32 currentBufferSize = mDecoder->GetFrameBufferLength();
  if (currentBufferSize == 0) {
    NS_WARNING("Decoder framebuffer length not set.");
    return;
  }

  if (!mSignalBuffer ||
      (mSignalBufferPosition == 0 && mSignalBufferLength != currentBufferSize)) {
    if (!mSignalBuffer || (mSignalBufferLength < currentBufferSize)) {
      // Only resize if buffer is empty or smaller.
      mSignalBuffer = new float[currentBufferSize];
    }
    mSignalBufferLength = currentBufferSize;
  }
  SoundDataValue* audioData = aAudioData;
  PRUint32 audioDataLength = aAudioDataLength;
  PRUint32 signalBufferTail = mSignalBufferLength - mSignalBufferPosition;

  // Group audio samples into optimal size for event dispatch, and queue.
  while (signalBufferTail <= audioDataLength) {
    float time = 0.0;
    // Guard against unsigned number overflow during first frame time calculation.
    if (aEndTimeSampleOffset > mSignalBufferPosition + audioDataLength) {
      time = (aEndTimeSampleOffset - mSignalBufferPosition - audioDataLength) / 
             mSamplesPerSecond;
    }

    // Fill the signalBuffer.
    PRUint32 i;
    float *signalBuffer = mSignalBuffer.get() + mSignalBufferPosition;
    for (i = 0; i < signalBufferTail; ++i) {
      signalBuffer[i] = MOZ_CONVERT_SOUND_SAMPLE(audioData[i]);
    }
    audioData += signalBufferTail;
    audioDataLength -= signalBufferTail;

    MonitorAutoEnter mon(mMonitor);

    if (mPendingEvents.Length() > 0) {
      // Check last event timecode to make sure that all queued events
      // are in non-descending sequence.
      nsAudioAvailableEventRunner* lastPendingEvent =
        (nsAudioAvailableEventRunner*)mPendingEvents[mPendingEvents.Length() - 1].get();
      if (lastPendingEvent->mTime > time) {
        // Clear the queue to start a fresh sequence.
        mPendingEvents.Clear();
      } else if (mPendingEvents.Length() >= MAX_PENDING_EVENTS) {
        NS_WARNING("Hit audio event queue max.");
        mPendingEvents.RemoveElementsAt(0, mPendingEvents.Length() - MAX_PENDING_EVENTS + 1);
      }
    }

    // Inform the element that we've written sound data.
    nsCOMPtr<nsIRunnable> event =
      new nsAudioAvailableEventRunner(mDecoder, mSignalBuffer.forget(),
                                      mSignalBufferLength, time);
    mPendingEvents.AppendElement(event);

    // Reset the buffer
    mSignalBufferLength = currentBufferSize;
    mSignalBuffer = new float[currentBufferSize];
    mSignalBufferPosition = 0;
    signalBufferTail = currentBufferSize;
    NS_ASSERTION(audioDataLength >= 0, "Past new signal data length.");
  }

  NS_ASSERTION(mSignalBufferPosition + audioDataLength < mSignalBufferLength,
               "Intermediate signal buffer must fit at least one more item.");

  if (audioDataLength > 0) {
    // Add data to the signalBuffer.
    PRUint32 i;
    float *signalBuffer = mSignalBuffer.get() + mSignalBufferPosition;
    for (i = 0; i < audioDataLength; ++i) {
      signalBuffer[i] = MOZ_CONVERT_SOUND_SAMPLE(audioData[i]);
    }
    mSignalBufferPosition += audioDataLength;
  }
}

void nsAudioAvailableEventManager::Clear()
{
  MonitorAutoEnter mon(mMonitor);

  mPendingEvents.Clear();
  mSignalBufferPosition = 0;
}

void nsAudioAvailableEventManager::Drain(PRUint64 aEndTime)
{
  MonitorAutoEnter mon(mMonitor);

  // Force all pending events to go now.
  for (PRUint32 i = 0; i < mPendingEvents.Length(); ++i) {
    nsCOMPtr<nsIRunnable> event = mPendingEvents[i];
    NS_DispatchToMainThread(event, NS_DISPATCH_NORMAL);
  }
  mPendingEvents.Clear();

  // If there is anything left in the signal buffer, put it in an event and fire.
  if (0 == mSignalBufferPosition)
    return;

  // Zero-pad the end of the signal buffer so it's complete.
  memset(mSignalBuffer.get() + mSignalBufferPosition, 0,
         (mSignalBufferLength - mSignalBufferPosition) * sizeof(float));

  // Force this last event to go now.
  float time = (aEndTime / MILLISECONDS_PER_SECOND) - 
               (mSignalBufferPosition / mSamplesPerSecond);
  nsCOMPtr<nsIRunnable> lastEvent =
    new nsAudioAvailableEventRunner(mDecoder, mSignalBuffer.forget(),
                                    mSignalBufferLength, time);
  NS_DispatchToMainThread(lastEvent, NS_DISPATCH_NORMAL);

  mSignalBufferPosition = 0;
}