1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/webaudio/DelayBuffer.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,269 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim:set ts=2 sw=2 sts=2 et cindent: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "DelayBuffer.h"
1.11 +
1.12 +#include "mozilla/PodOperations.h"
1.13 +#include "AudioChannelFormat.h"
1.14 +#include "AudioNodeEngine.h"
1.15 +
1.16 +namespace mozilla {
1.17 +
1.18 +size_t
1.19 +DelayBuffer::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
1.20 +{
1.21 + size_t amount = 0;
1.22 + amount += mChunks.SizeOfExcludingThis(aMallocSizeOf);
1.23 + for (size_t i = 0; i < mChunks.Length(); i++) {
1.24 + amount += mChunks[i].SizeOfExcludingThis(aMallocSizeOf, false);
1.25 + }
1.26 +
1.27 + amount += mUpmixChannels.SizeOfExcludingThis(aMallocSizeOf);
1.28 + return amount;
1.29 +}
1.30 +
1.31 +void
1.32 +DelayBuffer::Write(const AudioChunk& aInputChunk)
1.33 +{
1.34 + // We must have a reference to the buffer if there are channels
1.35 + MOZ_ASSERT(aInputChunk.IsNull() == !aInputChunk.mChannelData.Length());
1.36 +#ifdef DEBUG
1.37 + MOZ_ASSERT(!mHaveWrittenBlock);
1.38 + mHaveWrittenBlock = true;
1.39 +#endif
1.40 +
1.41 + if (!EnsureBuffer()) {
1.42 + return;
1.43 + }
1.44 +
1.45 + if (mCurrentChunk == mLastReadChunk) {
1.46 + mLastReadChunk = -1; // invalidate cache
1.47 + }
1.48 + mChunks[mCurrentChunk] = aInputChunk;
1.49 +}
1.50 +
1.51 +void
1.52 +DelayBuffer::Read(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.53 + AudioChunk* aOutputChunk,
1.54 + ChannelInterpretation aChannelInterpretation)
1.55 +{
1.56 + int chunkCount = mChunks.Length();
1.57 + if (!chunkCount) {
1.58 + aOutputChunk->SetNull(WEBAUDIO_BLOCK_SIZE);
1.59 + return;
1.60 + }
1.61 +
1.62 + // Find the maximum number of contributing channels to determine the output
1.63 + // channel count that retains all signal information. Buffered blocks will
1.64 + // be upmixed if necessary.
1.65 + //
1.66 + // First find the range of "delay" offsets backwards from the current
1.67 + // position. Note that these may be negative for frames that are after the
1.68 + // current position (including i).
1.69 + double minDelay = aPerFrameDelays[0];
1.70 + double maxDelay = minDelay;
1.71 + for (unsigned i = 1; i < WEBAUDIO_BLOCK_SIZE; ++i) {
1.72 + minDelay = std::min(minDelay, aPerFrameDelays[i] - i);
1.73 + maxDelay = std::max(maxDelay, aPerFrameDelays[i] - i);
1.74 + }
1.75 +
1.76 + // Now find the chunks touched by this range and check their channel counts.
1.77 + int oldestChunk = ChunkForDelay(int(maxDelay) + 1);
1.78 + int youngestChunk = ChunkForDelay(minDelay);
1.79 +
1.80 + uint32_t channelCount = 0;
1.81 + for (int i = oldestChunk; true; i = (i + 1) % chunkCount) {
1.82 + channelCount = GetAudioChannelsSuperset(channelCount,
1.83 + mChunks[i].ChannelCount());
1.84 + if (i == youngestChunk) {
1.85 + break;
1.86 + }
1.87 + }
1.88 +
1.89 + if (channelCount) {
1.90 + AllocateAudioBlock(channelCount, aOutputChunk);
1.91 + ReadChannels(aPerFrameDelays, aOutputChunk,
1.92 + 0, channelCount, aChannelInterpretation);
1.93 + } else {
1.94 + aOutputChunk->SetNull(WEBAUDIO_BLOCK_SIZE);
1.95 + }
1.96 +
1.97 + // Remember currentDelayFrames for the next ProcessBlock call
1.98 + mCurrentDelay = aPerFrameDelays[WEBAUDIO_BLOCK_SIZE - 1];
1.99 +}
1.100 +
1.101 +void
1.102 +DelayBuffer::ReadChannel(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.103 + const AudioChunk* aOutputChunk, uint32_t aChannel,
1.104 + ChannelInterpretation aChannelInterpretation)
1.105 +{
1.106 + if (!mChunks.Length()) {
1.107 + float* outputChannel = static_cast<float*>
1.108 + (const_cast<void*>(aOutputChunk->mChannelData[aChannel]));
1.109 + PodZero(outputChannel, WEBAUDIO_BLOCK_SIZE);
1.110 + return;
1.111 + }
1.112 +
1.113 + ReadChannels(aPerFrameDelays, aOutputChunk,
1.114 + aChannel, 1, aChannelInterpretation);
1.115 +}
1.116 +
1.117 +void
1.118 +DelayBuffer::ReadChannels(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.119 + const AudioChunk* aOutputChunk,
1.120 + uint32_t aFirstChannel, uint32_t aNumChannelsToRead,
1.121 + ChannelInterpretation aChannelInterpretation)
1.122 +{
1.123 + uint32_t totalChannelCount = aOutputChunk->mChannelData.Length();
1.124 + uint32_t readChannelsEnd = aFirstChannel + aNumChannelsToRead;
1.125 + MOZ_ASSERT(readChannelsEnd <= totalChannelCount);
1.126 +
1.127 + if (mUpmixChannels.Length() != totalChannelCount) {
1.128 + mLastReadChunk = -1; // invalidate cache
1.129 + }
1.130 +
1.131 + float* const* outputChannels = reinterpret_cast<float* const*>
1.132 + (const_cast<void* const*>(aOutputChunk->mChannelData.Elements()));
1.133 + for (uint32_t channel = aFirstChannel;
1.134 + channel < readChannelsEnd; ++channel) {
1.135 + PodZero(outputChannels[channel], WEBAUDIO_BLOCK_SIZE);
1.136 + }
1.137 +
1.138 + for (unsigned i = 0; i < WEBAUDIO_BLOCK_SIZE; ++i) {
1.139 + double currentDelay = aPerFrameDelays[i];
1.140 + MOZ_ASSERT(currentDelay >= 0.0);
1.141 + MOZ_ASSERT(currentDelay <= (mChunks.Length() - 1) * WEBAUDIO_BLOCK_SIZE);
1.142 +
1.143 + // Interpolate two input frames in case the read position does not match
1.144 + // an integer index.
1.145 + // Use the larger delay, for the older frame, first, as this is more
1.146 + // likely to use the cached upmixed channel arrays.
1.147 + int floorDelay = int(currentDelay);
1.148 + double interpolationFactor = currentDelay - floorDelay;
1.149 + int positions[2];
1.150 + positions[1] = PositionForDelay(floorDelay) + i;
1.151 + positions[0] = positions[1] - 1;
1.152 +
1.153 + for (unsigned tick = 0; tick < ArrayLength(positions); ++tick) {
1.154 + int readChunk = ChunkForPosition(positions[tick]);
1.155 + // mVolume is not set on default initialized chunks so handle null
1.156 + // chunks specially.
1.157 + if (!mChunks[readChunk].IsNull()) {
1.158 + int readOffset = OffsetForPosition(positions[tick]);
1.159 + UpdateUpmixChannels(readChunk, totalChannelCount,
1.160 + aChannelInterpretation);
1.161 + double multiplier = interpolationFactor * mChunks[readChunk].mVolume;
1.162 + for (uint32_t channel = aFirstChannel;
1.163 + channel < readChannelsEnd; ++channel) {
1.164 + outputChannels[channel][i] += multiplier *
1.165 + static_cast<const float*>(mUpmixChannels[channel])[readOffset];
1.166 + }
1.167 + }
1.168 +
1.169 + interpolationFactor = 1.0 - interpolationFactor;
1.170 + }
1.171 + }
1.172 +}
1.173 +
1.174 +void
1.175 +DelayBuffer::Read(double aDelayTicks, AudioChunk* aOutputChunk,
1.176 + ChannelInterpretation aChannelInterpretation)
1.177 +{
1.178 + const bool firstTime = mCurrentDelay < 0.0;
1.179 + double currentDelay = firstTime ? aDelayTicks : mCurrentDelay;
1.180 +
1.181 + double computedDelay[WEBAUDIO_BLOCK_SIZE];
1.182 +
1.183 + for (unsigned i = 0; i < WEBAUDIO_BLOCK_SIZE; ++i) {
1.184 + // If the value has changed, smoothly approach it
1.185 + currentDelay += (aDelayTicks - currentDelay) * mSmoothingRate;
1.186 + computedDelay[i] = currentDelay;
1.187 + }
1.188 +
1.189 + Read(computedDelay, aOutputChunk, aChannelInterpretation);
1.190 +}
1.191 +
1.192 +bool
1.193 +DelayBuffer::EnsureBuffer()
1.194 +{
1.195 + if (mChunks.Length() == 0) {
1.196 + // The length of the buffer is at least one block greater than the maximum
1.197 + // delay so that writing an input block does not overwrite the block that
1.198 + // would subsequently be read at maximum delay. Also round up to the next
1.199 + // block size, so that no block of writes will need to wrap.
1.200 + const int chunkCount = (mMaxDelayTicks + 2 * WEBAUDIO_BLOCK_SIZE - 1) >>
1.201 + WEBAUDIO_BLOCK_SIZE_BITS;
1.202 + if (!mChunks.SetLength(chunkCount)) {
1.203 + return false;
1.204 + }
1.205 +
1.206 + mLastReadChunk = -1;
1.207 + }
1.208 + return true;
1.209 +}
1.210 +
1.211 +int
1.212 +DelayBuffer::PositionForDelay(int aDelay) {
1.213 + // Adding mChunks.Length() keeps integers positive for defined and
1.214 + // appropriate bitshift, remainder, and bitwise operations.
1.215 + return ((mCurrentChunk + mChunks.Length()) * WEBAUDIO_BLOCK_SIZE) - aDelay;
1.216 +}
1.217 +
1.218 +int
1.219 +DelayBuffer::ChunkForPosition(int aPosition)
1.220 +{
1.221 + MOZ_ASSERT(aPosition >= 0);
1.222 + return (aPosition >> WEBAUDIO_BLOCK_SIZE_BITS) % mChunks.Length();
1.223 +}
1.224 +
1.225 +int
1.226 +DelayBuffer::OffsetForPosition(int aPosition)
1.227 +{
1.228 + MOZ_ASSERT(aPosition >= 0);
1.229 + return aPosition & (WEBAUDIO_BLOCK_SIZE - 1);
1.230 +}
1.231 +
1.232 +int
1.233 +DelayBuffer::ChunkForDelay(int aDelay)
1.234 +{
1.235 + return ChunkForPosition(PositionForDelay(aDelay));
1.236 +}
1.237 +
1.238 +void
1.239 +DelayBuffer::UpdateUpmixChannels(int aNewReadChunk, uint32_t aChannelCount,
1.240 + ChannelInterpretation aChannelInterpretation)
1.241 +{
1.242 + if (aNewReadChunk == mLastReadChunk) {
1.243 + MOZ_ASSERT(mUpmixChannels.Length() == aChannelCount);
1.244 + return;
1.245 + }
1.246 +
1.247 + static const float silenceChannel[WEBAUDIO_BLOCK_SIZE] = {};
1.248 +
1.249 + NS_WARN_IF_FALSE(mHaveWrittenBlock || aNewReadChunk != mCurrentChunk,
1.250 + "Smoothing is making feedback delay too small.");
1.251 +
1.252 + mLastReadChunk = aNewReadChunk;
1.253 + // Missing assignment operator is bug 976927
1.254 + mUpmixChannels.ReplaceElementsAt(0, mUpmixChannels.Length(),
1.255 + mChunks[aNewReadChunk].mChannelData);
1.256 + MOZ_ASSERT(mUpmixChannels.Length() <= aChannelCount);
1.257 + if (mUpmixChannels.Length() < aChannelCount) {
1.258 + if (aChannelInterpretation == ChannelInterpretation::Speakers) {
1.259 + AudioChannelsUpMix(&mUpmixChannels, aChannelCount, silenceChannel);
1.260 + MOZ_ASSERT(mUpmixChannels.Length() == aChannelCount,
1.261 + "We called GetAudioChannelsSuperset to avoid this");
1.262 + } else {
1.263 + // Fill up the remaining channels with zeros
1.264 + for (uint32_t channel = mUpmixChannels.Length();
1.265 + channel < aChannelCount; ++channel) {
1.266 + mUpmixChannels.AppendElement(silenceChannel);
1.267 + }
1.268 + }
1.269 + }
1.270 +}
1.271 +
1.272 +} // mozilla
