gecko/content/media/webaudio/AudioBufferSourceNode.cpp
Ehsan Akhgari e48730f81b Bug 849713 - Part 5: Implement the looping logic in AudioBufferSourceNodeEngine; r=roc
The logic in this function is based around a while loop.  In every
iteration of the loop, we determine whether we need to output silence
(if we're at a position before the playback has started or after it has
stopped) or if we need to produce sound.  In each case, we call a helper
function which eagerly tries to produce as much silence or sound as
possible, while maintaining the constraints that are explained in the
comments in the code.
2013-03-10 21:02:22 -04:00

337 lines
11 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "AudioBufferSourceNode.h"
#include "mozilla/dom/AudioBufferSourceNodeBinding.h"
#include "nsMathUtils.h"
#include "AudioNodeEngine.h"
#include "AudioNodeStream.h"
namespace mozilla {
namespace dom {
NS_IMPL_CYCLE_COLLECTION_INHERITED_1(AudioBufferSourceNode, AudioSourceNode, mBuffer)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(AudioBufferSourceNode)
NS_INTERFACE_MAP_END_INHERITING(AudioSourceNode)
NS_IMPL_ADDREF_INHERITED(AudioBufferSourceNode, AudioSourceNode)
NS_IMPL_RELEASE_INHERITED(AudioBufferSourceNode, AudioSourceNode)
class AudioBufferSourceNodeEngine : public AudioNodeEngine
{
public:
AudioBufferSourceNodeEngine() :
mStart(0), mStop(TRACK_TICKS_MAX),
mOffset(0), mDuration(0),
mLoop(false), mLoopStart(0), mLoopEnd(0)
{}
// START, OFFSET and DURATION are always set by start() (along with setting
// mBuffer to something non-null).
// STOP is set by stop().
enum Parameters {
START,
STOP,
OFFSET,
DURATION,
LOOP,
LOOPSTART,
LOOPEND
};
virtual void SetStreamTimeParameter(uint32_t aIndex, TrackTicks aParam)
{
switch (aIndex) {
case START: mStart = aParam; break;
case STOP: mStop = aParam; break;
default:
NS_ERROR("Bad AudioBufferSourceNodeEngine StreamTimeParameter");
}
}
virtual void SetInt32Parameter(uint32_t aIndex, int32_t aParam)
{
switch (aIndex) {
case OFFSET: mOffset = aParam; break;
case DURATION: mDuration = aParam; break;
case LOOP: mLoop = !!aParam; break;
case LOOPSTART: mLoopStart = aParam; break;
case LOOPEND: mLoopEnd = aParam; break;
default:
NS_ERROR("Bad AudioBufferSourceNodeEngine Int32Parameter");
}
}
virtual void SetBuffer(already_AddRefed<ThreadSharedFloatArrayBufferList> aBuffer)
{
mBuffer = aBuffer;
}
// Borrow a full buffer of size WEBAUDIO_BLOCK_SIZE from the source buffer
// at offset aSourceOffset. This avoids copying memory.
void BorrowFromInputBuffer(AudioChunk* aOutput,
uint32_t aChannels,
uintptr_t aSourceOffset)
{
aOutput->mDuration = WEBAUDIO_BLOCK_SIZE;
aOutput->mBuffer = mBuffer;
aOutput->mChannelData.SetLength(aChannels);
for (uint32_t i = 0; i < aChannels; ++i) {
aOutput->mChannelData[i] = mBuffer->GetData(i) + aSourceOffset;
}
aOutput->mVolume = 1.0f;
aOutput->mBufferFormat = AUDIO_FORMAT_FLOAT32;
}
// Copy aNumberOfFrames frames from the source buffer at offset aSourceOffset
// and put it at offset aBufferOffset in the destination buffer.
void CopyFromInputBuffer(AudioChunk* aOutput,
uint32_t aChannels,
uintptr_t aSourceOffset,
uintptr_t aBufferOffset,
uint32_t aNumberOfFrames) {
for (uint32_t i = 0; i < aChannels; ++i) {
float* baseChannelData = static_cast<float*>(const_cast<void*>(aOutput->mChannelData[i]));
memcpy(baseChannelData + aBufferOffset,
mBuffer->GetData(i) + aSourceOffset,
aNumberOfFrames * sizeof(float));
}
}
/**
* Fill aOutput with as many zero frames as we can, and advance
* aOffsetWithinBlock and aCurrentPosition based on how many frames we write.
* This will never advance aOffsetWithinBlock past WEBAUDIO_BLOCK_SIZE or
* aCurrentPosition past aMaxPos. This function knows when it needs to
* allocate the output buffer, and also optimizes the case where it can avoid
* memory allocations.
*/
void FillWithZeroes(AudioChunk* aOutput,
uint32_t aChannels,
uint32_t* aOffsetWithinBlock,
TrackTicks* aCurrentPosition,
TrackTicks aMaxPos)
{
uint32_t numFrames = std::min(WEBAUDIO_BLOCK_SIZE - *aOffsetWithinBlock,
uint32_t(aMaxPos - *aCurrentPosition));
if (numFrames == WEBAUDIO_BLOCK_SIZE) {
aOutput->SetNull(numFrames);
} else {
if (aOutput->IsNull()) {
AllocateAudioBlock(aChannels, aOutput);
}
WriteZeroesToAudioBlock(aOutput, *aOffsetWithinBlock, numFrames);
}
*aOffsetWithinBlock += numFrames;
*aCurrentPosition += numFrames;
}
/**
* Copy as many frames as possible from the source buffer to aOutput, and
* advance aOffsetWithinBlock and aCurrentPosition based on how many frames
* we copy. This will never advance aOffsetWithinBlock past
* WEBAUDIO_BLOCK_SIZE, or aCurrentPosition past mStop. It takes data from
* the buffer at aBufferOffset, and never takes more data than aBufferMax.
* This function knows when it needs to allocate the output buffer, and also
* optimizes the case where it can avoid memory allocations.
*/
void CopyFromBuffer(AudioChunk* aOutput,
uint32_t aChannels,
uint32_t* aOffsetWithinBlock,
TrackTicks* aCurrentPosition,
uint32_t aBufferOffset,
uint32_t aBufferMax)
{
uint32_t numFrames = std::min(std::min(WEBAUDIO_BLOCK_SIZE - *aOffsetWithinBlock,
aBufferMax - aBufferOffset),
uint32_t(mStop - *aCurrentPosition));
if (numFrames == WEBAUDIO_BLOCK_SIZE) {
BorrowFromInputBuffer(aOutput, aChannels, aBufferOffset);
} else {
if (aOutput->IsNull()) {
AllocateAudioBlock(aChannels, aOutput);
}
CopyFromInputBuffer(aOutput, aChannels, aBufferOffset, *aOffsetWithinBlock, numFrames);
}
*aOffsetWithinBlock += numFrames;
*aCurrentPosition += numFrames;
}
virtual void ProduceAudioBlock(AudioNodeStream* aStream,
const AudioChunk& aInput,
AudioChunk* aOutput,
bool* aFinished)
{
if (!mBuffer)
return;
uint32_t channels = mBuffer->GetChannels();
if (!channels) {
aOutput->SetNull(WEBAUDIO_BLOCK_SIZE);
return;
}
uint32_t written = 0;
TrackTicks currentPosition = aStream->GetCurrentPosition();
while (written < WEBAUDIO_BLOCK_SIZE) {
if (mStop != TRACK_TICKS_MAX &&
currentPosition >= mStop) {
FillWithZeroes(aOutput, channels, &written, &currentPosition, TRACK_TICKS_MAX);
continue;
}
if (currentPosition < mStart) {
FillWithZeroes(aOutput, channels, &written, &currentPosition, mStart);
continue;
}
TrackTicks t = currentPosition - mStart;
if (mLoop) {
if (mOffset + t < mLoopEnd) {
CopyFromBuffer(aOutput, channels, &written, &currentPosition, mOffset + t, mLoopEnd);
} else {
uint32_t offsetInLoop = (mOffset + t - mLoopEnd) % (mLoopEnd - mLoopStart);
CopyFromBuffer(aOutput, channels, &written, &currentPosition, mLoopStart + offsetInLoop, mLoopEnd);
}
} else {
if (mOffset + t < mDuration) {
CopyFromBuffer(aOutput, channels, &written, &currentPosition, mOffset + t, mDuration);
} else {
FillWithZeroes(aOutput, channels, &written, &currentPosition, TRACK_TICKS_MAX);
}
}
}
// We've finished if we've gone past mStop, or if we're past mDuration when
// looping is disabled.
if (currentPosition >= mStop ||
(!mLoop && currentPosition - mStart + mOffset > mDuration)) {
*aFinished = true;
}
}
TrackTicks mStart;
TrackTicks mStop;
nsRefPtr<ThreadSharedFloatArrayBufferList> mBuffer;
int32_t mOffset;
int32_t mDuration;
bool mLoop;
int32_t mLoopStart;
int32_t mLoopEnd;
};
AudioBufferSourceNode::AudioBufferSourceNode(AudioContext* aContext)
: AudioSourceNode(aContext)
, mLoopStart(0.0)
, mLoopEnd(0.0)
, mLoop(false)
, mStartCalled(false)
{
SetProduceOwnOutput(true);
mStream = aContext->Graph()->CreateAudioNodeStream(new AudioBufferSourceNodeEngine());
mStream->AddMainThreadListener(this);
}
AudioBufferSourceNode::~AudioBufferSourceNode()
{
DestroyMediaStream();
}
JSObject*
AudioBufferSourceNode::WrapObject(JSContext* aCx, JSObject* aScope)
{
return AudioBufferSourceNodeBinding::Wrap(aCx, aScope, this);
}
void
AudioBufferSourceNode::Start(JSContext* aCx, double aWhen, double aOffset,
const Optional<double>& aDuration, ErrorResult& aRv)
{
if (mStartCalled) {
aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
return;
}
mStartCalled = true;
AudioNodeStream* ns = static_cast<AudioNodeStream*>(mStream.get());
if (!mBuffer || !ns) {
// Nothing to play, or we're already dead for some reason
return;
}
uint32_t rate = Context()->GetRate();
uint32_t lengthSamples;
nsRefPtr<ThreadSharedFloatArrayBufferList> data =
mBuffer->GetThreadSharedChannelsForRate(aCx, rate, &lengthSamples);
double length = double(lengthSamples)/rate;
double offset = std::max(0.0, aOffset);
double endOffset = aDuration.WasPassed() ?
std::min(aOffset + aDuration.Value(), length) : length;
if (offset >= endOffset) {
return;
}
// Don't compute and set the loop parameters unnecessarily
if (mLoop) {
double actualLoopStart, actualLoopEnd;
if (((mLoopStart != 0.0) || (mLoopEnd != 0.0)) &&
mLoopStart >= 0.0 && mLoopEnd > 0.0 &&
mLoopStart < mLoopEnd) {
actualLoopStart = (mLoopStart > length) ? 0.0 : mLoopStart;
actualLoopEnd = std::min(mLoopEnd, length);
} else {
actualLoopStart = 0.0;
actualLoopEnd = length;
}
int32_t loopStartTicks = NS_lround(actualLoopStart * rate);
int32_t loopEndTicks = NS_lround(actualLoopEnd * rate);
ns->SetInt32Parameter(AudioBufferSourceNodeEngine::LOOP, 1);
ns->SetInt32Parameter(AudioBufferSourceNodeEngine::LOOPSTART, loopStartTicks);
ns->SetInt32Parameter(AudioBufferSourceNodeEngine::LOOPEND, loopEndTicks);
}
ns->SetBuffer(data.forget());
// Don't set parameter unnecessarily
if (aWhen > 0.0) {
ns->SetStreamTimeParameter(AudioBufferSourceNodeEngine::START,
Context()->DestinationStream(),
aWhen);
}
int32_t offsetTicks = NS_lround(offset*rate);
// Don't set parameter unnecessarily
if (offsetTicks > 0) {
ns->SetInt32Parameter(AudioBufferSourceNodeEngine::OFFSET, offsetTicks);
}
ns->SetInt32Parameter(AudioBufferSourceNodeEngine::DURATION,
NS_lround(endOffset*rate) - offsetTicks);
}
void
AudioBufferSourceNode::Stop(double aWhen, ErrorResult& aRv)
{
if (!mStartCalled) {
aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
return;
}
AudioNodeStream* ns = static_cast<AudioNodeStream*>(mStream.get());
if (!ns) {
// We've already stopped and had our stream shut down
return;
}
ns->SetStreamTimeParameter(AudioBufferSourceNodeEngine::STOP,
Context()->DestinationStream(),
std::max(0.0, aWhen));
}
void
AudioBufferSourceNode::NotifyMainThreadStateChanged()
{
if (mStream->IsFinished()) {
SetProduceOwnOutput(false);
}
}
}
}