gecko/content/media/nsAudioAvailableEventManager.cpp

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/* ***** BEGIN LICENSE BLOCK *****
 * 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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 *
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 * 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
#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, PRUint64 aTime) :
    mDecoder(aDecoder),
    mFrameBuffer(aFrameBuffer),
    mFrameBufferLength(aFrameBufferLength),
    mTime(aTime)
  {
  }

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

  const PRUint32 mFrameBufferLength;
  const PRUint64 mTime;
};


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

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

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

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

void nsAudioAvailableEventManager::QueueWrittenAudioData(float* 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;
  }
  float* audioData = aAudioData;
  PRUint32 audioDataLength = aAudioDataLength;
  PRUint32 signalBufferTail = mSignalBufferLength - mSignalBufferPosition;

  // Group audio samples into optimal size for event dispatch, and queue.
  while (signalBufferTail <= audioDataLength) {
    PRUint64 time = 0;
    // Guard against unsigned number overflow during first frame time calculation.
    if (aEndTimeSampleOffset > mSignalBufferPosition + audioDataLength) {
      time = MILLISECONDS_PER_SECOND * (aEndTimeSampleOffset -
             mSignalBufferPosition - audioDataLength) / mSamplesPerSecond;
    }

    // Fill the signalBuffer.
    memcpy(mSignalBuffer.get() + mSignalBufferPosition,
           audioData, sizeof(float) * signalBufferTail);
    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.
    memcpy(mSignalBuffer.get() + mSignalBufferPosition,
           audioData, sizeof(float) * audioDataLength);
    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.
  nsCOMPtr<nsIRunnable> lastEvent =
    new nsAudioAvailableEventRunner(mDecoder, mSignalBuffer.forget(),
                                    mSignalBufferLength, aEndTime);
  NS_DispatchToMainThread(lastEvent, NS_DISPATCH_NORMAL);

  mSignalBufferPosition = 0;
}