Source code
Revision control
Copy as Markdown
Other Tools
/* -*- 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
#ifndef MOZILLA_AUDIOBLOCK_H_
#define MOZILLA_AUDIOBLOCK_H_
#include "AudioSegment.h"
namespace mozilla {
/**
* An AudioChunk whose buffer contents need to be valid only for one
* processing block iteration, after which contents can be overwritten if the
* buffer has not been passed to longer term storage or to another thread,
* which may happen though AsAudioChunk() or AsMutableChunk().
*
* Use on graph thread only.
*/
class AudioBlock : private AudioChunk {
public:
AudioBlock() {
mDuration = WEBAUDIO_BLOCK_SIZE;
mBufferFormat = AUDIO_FORMAT_SILENCE;
}
// No effort is made in constructors to ensure that mBufferIsDownstreamRef
// is set because the block is expected to be a temporary and so the
// reference will be released before the next iteration.
// The custom copy constructor is required so as not to set
// mBufferIsDownstreamRef without notifying AudioBlockBuffer.
AudioBlock(const AudioBlock& aBlock) : AudioChunk(aBlock.AsAudioChunk()) {}
explicit AudioBlock(const AudioChunk& aChunk) : AudioChunk(aChunk) {
MOZ_ASSERT(aChunk.mDuration == WEBAUDIO_BLOCK_SIZE);
}
~AudioBlock();
using AudioChunk::ChannelCount;
using AudioChunk::ChannelData;
using AudioChunk::GetDuration;
using AudioChunk::IsNull;
using AudioChunk::SizeOfExcludingThis;
using AudioChunk::SizeOfExcludingThisIfUnshared;
// mDuration is not exposed. Use GetDuration().
// mBuffer is not exposed. Use Get/SetBuffer().
using AudioChunk::mBufferFormat;
using AudioChunk::mChannelData;
using AudioChunk::mVolume;
const AudioChunk& AsAudioChunk() const { return *this; }
AudioChunk* AsMutableChunk() {
ClearDownstreamMark();
return this;
}
/**
* Allocates, if necessary, aChannelCount buffers of WEBAUDIO_BLOCK_SIZE float
* samples for writing.
*/
void AllocateChannels(uint32_t aChannelCount);
/**
* ChannelFloatsForWrite() should only be used when the buffers have been
* created with AllocateChannels().
*/
float* ChannelFloatsForWrite(size_t aChannel) {
MOZ_ASSERT(mBufferFormat == AUDIO_FORMAT_FLOAT32);
MOZ_ASSERT(CanWrite());
return static_cast<float*>(const_cast<void*>(mChannelData[aChannel]));
}
ThreadSharedObject* GetBuffer() const { return mBuffer; }
void SetBuffer(ThreadSharedObject* aNewBuffer);
void SetNull(TrackTime aDuration) {
MOZ_ASSERT(aDuration == WEBAUDIO_BLOCK_SIZE);
SetBuffer(nullptr);
mChannelData.Clear();
mVolume = 1.0f;
mBufferFormat = AUDIO_FORMAT_SILENCE;
}
AudioBlock& operator=(const AudioBlock& aBlock) {
// Instead of just copying, mBufferIsDownstreamRef must be first cleared
// if set. It is set again for the new mBuffer if possible. This happens
// in SetBuffer().
return *this = aBlock.AsAudioChunk();
}
AudioBlock& operator=(const AudioChunk& aChunk) {
MOZ_ASSERT(aChunk.mDuration == WEBAUDIO_BLOCK_SIZE);
SetBuffer(aChunk.mBuffer);
mChannelData = aChunk.mChannelData;
mVolume = aChunk.mVolume;
mBufferFormat = aChunk.mBufferFormat;
return *this;
}
bool IsMuted() const { return mVolume == 0.0f; }
bool IsSilentOrSubnormal() const {
if (!mBuffer) {
return true;
}
for (uint32_t i = 0, length = mChannelData.Length(); i < length; ++i) {
const float* channel = static_cast<const float*>(mChannelData[i]);
for (TrackTime frame = 0; frame < mDuration; ++frame) {
if (fabs(channel[frame]) >= FLT_MIN) {
return false;
}
}
}
return true;
}
private:
void ClearDownstreamMark();
bool CanWrite();
// mBufferIsDownstreamRef is set only when mBuffer references an
// AudioBlockBuffer created in a different AudioBlock. That can happen when
// this AudioBlock is on a node downstream from the node which created the
// buffer. When this is set, the AudioBlockBuffer is notified that this
// reference does not prevent the upstream node from re-using the buffer next
// iteration and modifying its contents. The AudioBlockBuffer is also
// notified when mBuffer releases this reference.
bool mBufferIsDownstreamRef = false;
};
} // namespace mozilla
MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::AudioBlock)
#endif // MOZILLA_AUDIOBLOCK_H_