1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/webaudio/DelayBuffer.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,114 @@
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 +#ifndef DelayBuffer_h_
1.11 +#define DelayBuffer_h_
1.12 +
1.13 +#include "nsTArray.h"
1.14 +#include "AudioSegment.h"
1.15 +#include "mozilla/dom/AudioNodeBinding.h" // for ChannelInterpretation
1.16 +
1.17 +namespace mozilla {
1.18 +
1.19 +class DelayBuffer {
1.20 + typedef dom::ChannelInterpretation ChannelInterpretation;
1.21 +
1.22 +public:
1.23 + // See WebAudioUtils::ComputeSmoothingRate() for frame to frame exponential
1.24 + // |smoothingRate| multiplier.
1.25 + DelayBuffer(double aMaxDelayTicks, double aSmoothingRate)
1.26 + : mSmoothingRate(aSmoothingRate)
1.27 + , mCurrentDelay(-1.0)
1.28 + // Round the maximum delay up to the next tick.
1.29 + , mMaxDelayTicks(ceil(aMaxDelayTicks))
1.30 + , mCurrentChunk(0)
1.31 + // mLastReadChunk is initialized in EnsureBuffer
1.32 +#ifdef DEBUG
1.33 + , mHaveWrittenBlock(false)
1.34 +#endif
1.35 + {
1.36 + // The 180 second limit in AudioContext::CreateDelay() and the
1.37 + // 1 << MEDIA_TIME_FRAC_BITS limit on sample rate provide a limit on the
1.38 + // maximum delay.
1.39 + MOZ_ASSERT(aMaxDelayTicks <=
1.40 + std::numeric_limits<decltype(mMaxDelayTicks)>::max());
1.41 + }
1.42 +
1.43 + // Write a WEBAUDIO_BLOCK_SIZE block for aChannelCount channels.
1.44 + void Write(const AudioChunk& aInputChunk);
1.45 +
1.46 + // Read a block with an array of delays, in ticks, for each sample frame.
1.47 + // Each delay should be >= 0 and <= MaxDelayTicks().
1.48 + void Read(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.49 + AudioChunk* aOutputChunk,
1.50 + ChannelInterpretation aChannelInterpretation);
1.51 + // Read a block with a constant delay, which will be smoothed with the
1.52 + // previous delay. The delay should be >= 0 and <= MaxDelayTicks().
1.53 + void Read(double aDelayTicks, AudioChunk* aOutputChunk,
1.54 + ChannelInterpretation aChannelInterpretation);
1.55 +
1.56 + // Read into one of the channels of aOutputChunk, given an array of
1.57 + // delays in ticks. This is useful when delays are different on different
1.58 + // channels. aOutputChunk must have already been allocated with at least as
1.59 + // many channels as were in any of the blocks passed to Write().
1.60 + void ReadChannel(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.61 + const AudioChunk* aOutputChunk, uint32_t aChannel,
1.62 + ChannelInterpretation aChannelInterpretation);
1.63 +
1.64 + // Advance the buffer pointer
1.65 + void NextBlock()
1.66 + {
1.67 + mCurrentChunk = (mCurrentChunk + 1) % mChunks.Length();
1.68 +#ifdef DEBUG
1.69 + MOZ_ASSERT(mHaveWrittenBlock);
1.70 + mHaveWrittenBlock = false;
1.71 +#endif
1.72 + }
1.73 +
1.74 + void Reset() {
1.75 + mChunks.Clear();
1.76 + mCurrentDelay = -1.0;
1.77 + };
1.78 +
1.79 + int MaxDelayTicks() const { return mMaxDelayTicks; }
1.80 +
1.81 + size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
1.82 +
1.83 +private:
1.84 + void ReadChannels(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
1.85 + const AudioChunk* aOutputChunk,
1.86 + uint32_t aFirstChannel, uint32_t aNumChannelsToRead,
1.87 + ChannelInterpretation aChannelInterpretation);
1.88 + bool EnsureBuffer();
1.89 + int PositionForDelay(int aDelay);
1.90 + int ChunkForPosition(int aPosition);
1.91 + int OffsetForPosition(int aPosition);
1.92 + int ChunkForDelay(int aDelay);
1.93 + void UpdateUpmixChannels(int aNewReadChunk, uint32_t channelCount,
1.94 + ChannelInterpretation aChannelInterpretation);
1.95 +
1.96 + // Circular buffer for capturing delayed samples.
1.97 + FallibleTArray<AudioChunk> mChunks;
1.98 + // Cache upmixed channel arrays.
1.99 + nsAutoTArray<const void*,GUESS_AUDIO_CHANNELS> mUpmixChannels;
1.100 + double mSmoothingRate;
1.101 + // Current delay, in fractional ticks
1.102 + double mCurrentDelay;
1.103 + // Maximum delay, in ticks
1.104 + int mMaxDelayTicks;
1.105 + // The current position in the circular buffer. The next write will be to
1.106 + // this chunk, and the next read may begin before this chunk.
1.107 + int mCurrentChunk;
1.108 + // The chunk owning the pointers in mUpmixChannels
1.109 + int mLastReadChunk;
1.110 +#ifdef DEBUG
1.111 + bool mHaveWrittenBlock;
1.112 +#endif
1.113 +};
1.114 +
1.115 +} // mozilla
1.116 +
1.117 +#endif // DelayBuffer_h_
