void AudioBufferSourceHandler::handleStoppableSourceNode()
{
// If the source node is not looping, and we have a buffer, we can determine when the source
// would stop playing. This is intended to handle the (uncommon) scenario where start() has
// been called but is never connected to the destination (directly or indirectly). By stopping
// the node, the node can be collected. Otherwise, the node will never get collected, leaking
// memory.
//
// If looping was ever done (m_didSetLooping = true), give up. We can't easily determine how
// long we looped so we don't know the actual duration thus far, so don't try to do anything
// fancy.
if (!m_didSetLooping && buffer() && isPlayingOrScheduled() && m_minPlaybackRate > 0) {
// Adjust the duration to include the playback rate. Only need to account for rate < 1
// which makes the sound last longer. For rate >= 1, the source stops sooner, but that's
// ok.
double actualDuration = buffer()->duration() / m_minPlaybackRate;
double stopTime = m_startTime + actualDuration;
// See crbug.com/478301. If a source node is started via start(), the source may not start
// at that time but one quantum (128 frames) later. But we compute the stop time based on
// the start time and the duration, so we end up stopping one quantum early. Thus, add a
// little extra time; we just need to stop the source sometime after it should have stopped
// if it hadn't already. We don't need to be super precise on when to stop.
double extraStopTime = kExtraStopFrames / static_cast<double>(context()->sampleRate());
stopTime += extraStopTime;
if (context()->currentTime() > stopTime) {
// The context time has passed the time when the source nodes should have stopped
// playing. Stop the node now and deref it. (But don't run the onEnded event because the
// source never actually played.)
finishWithoutOnEnded();
}
}
}
bool AudioBufferSourceNode::propagatesSilence() const
{
return !isPlayingOrScheduled() || hasFinished() || !m_buffer;
}