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comparison: content/media/webaudio/DelayBuffer.h
content/media/webaudio/DelayBuffer.h
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| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* vim:set ts=2 sw=2 sts=2 et cindent: */ | |
| 3 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef DelayBuffer_h_ | |
| 8 #define DelayBuffer_h_ | |
| 9 | |
| 10 #include "nsTArray.h" | |
| 11 #include "AudioSegment.h" | |
| 12 #include "mozilla/dom/AudioNodeBinding.h" // for ChannelInterpretation | |
| 13 | |
| 14 namespace mozilla { | |
| 15 | |
| 16 class DelayBuffer { | |
| 17 typedef dom::ChannelInterpretation ChannelInterpretation; | |
| 18 | |
| 19 public: | |
| 20 // See WebAudioUtils::ComputeSmoothingRate() for frame to frame exponential | |
| 21 // |smoothingRate| multiplier. | |
| 22 DelayBuffer(double aMaxDelayTicks, double aSmoothingRate) | |
| 23 : mSmoothingRate(aSmoothingRate) | |
| 24 , mCurrentDelay(-1.0) | |
| 25 // Round the maximum delay up to the next tick. | |
| 26 , mMaxDelayTicks(ceil(aMaxDelayTicks)) | |
| 27 , mCurrentChunk(0) | |
| 28 // mLastReadChunk is initialized in EnsureBuffer | |
| 29 #ifdef DEBUG | |
| 30 , mHaveWrittenBlock(false) | |
| 31 #endif | |
| 32 { | |
| 33 // The 180 second limit in AudioContext::CreateDelay() and the | |
| 34 // 1 << MEDIA_TIME_FRAC_BITS limit on sample rate provide a limit on the | |
| 35 // maximum delay. | |
| 36 MOZ_ASSERT(aMaxDelayTicks <= | |
| 37 std::numeric_limits<decltype(mMaxDelayTicks)>::max()); | |
| 38 } | |
| 39 | |
| 40 // Write a WEBAUDIO_BLOCK_SIZE block for aChannelCount channels. | |
| 41 void Write(const AudioChunk& aInputChunk); | |
| 42 | |
| 43 // Read a block with an array of delays, in ticks, for each sample frame. | |
| 44 // Each delay should be >= 0 and <= MaxDelayTicks(). | |
| 45 void Read(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], | |
| 46 AudioChunk* aOutputChunk, | |
| 47 ChannelInterpretation aChannelInterpretation); | |
| 48 // Read a block with a constant delay, which will be smoothed with the | |
| 49 // previous delay. The delay should be >= 0 and <= MaxDelayTicks(). | |
| 50 void Read(double aDelayTicks, AudioChunk* aOutputChunk, | |
| 51 ChannelInterpretation aChannelInterpretation); | |
| 52 | |
| 53 // Read into one of the channels of aOutputChunk, given an array of | |
| 54 // delays in ticks. This is useful when delays are different on different | |
| 55 // channels. aOutputChunk must have already been allocated with at least as | |
| 56 // many channels as were in any of the blocks passed to Write(). | |
| 57 void ReadChannel(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], | |
| 58 const AudioChunk* aOutputChunk, uint32_t aChannel, | |
| 59 ChannelInterpretation aChannelInterpretation); | |
| 60 | |
| 61 // Advance the buffer pointer | |
| 62 void NextBlock() | |
| 63 { | |
| 64 mCurrentChunk = (mCurrentChunk + 1) % mChunks.Length(); | |
| 65 #ifdef DEBUG | |
| 66 MOZ_ASSERT(mHaveWrittenBlock); | |
| 67 mHaveWrittenBlock = false; | |
| 68 #endif | |
| 69 } | |
| 70 | |
| 71 void Reset() { | |
| 72 mChunks.Clear(); | |
| 73 mCurrentDelay = -1.0; | |
| 74 }; | |
| 75 | |
| 76 int MaxDelayTicks() const { return mMaxDelayTicks; } | |
| 77 | |
| 78 size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const; | |
| 79 | |
| 80 private: | |
| 81 void ReadChannels(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], | |
| 82 const AudioChunk* aOutputChunk, | |
| 83 uint32_t aFirstChannel, uint32_t aNumChannelsToRead, | |
| 84 ChannelInterpretation aChannelInterpretation); | |
| 85 bool EnsureBuffer(); | |
| 86 int PositionForDelay(int aDelay); | |
| 87 int ChunkForPosition(int aPosition); | |
| 88 int OffsetForPosition(int aPosition); | |
| 89 int ChunkForDelay(int aDelay); | |
| 90 void UpdateUpmixChannels(int aNewReadChunk, uint32_t channelCount, | |
| 91 ChannelInterpretation aChannelInterpretation); | |
| 92 | |
| 93 // Circular buffer for capturing delayed samples. | |
| 94 FallibleTArray<AudioChunk> mChunks; | |
| 95 // Cache upmixed channel arrays. | |
| 96 nsAutoTArray<const void*,GUESS_AUDIO_CHANNELS> mUpmixChannels; | |
| 97 double mSmoothingRate; | |
| 98 // Current delay, in fractional ticks | |
| 99 double mCurrentDelay; | |
| 100 // Maximum delay, in ticks | |
| 101 int mMaxDelayTicks; | |
| 102 // The current position in the circular buffer. The next write will be to | |
| 103 // this chunk, and the next read may begin before this chunk. | |
| 104 int mCurrentChunk; | |
| 105 // The chunk owning the pointers in mUpmixChannels | |
| 106 int mLastReadChunk; | |
| 107 #ifdef DEBUG | |
| 108 bool mHaveWrittenBlock; | |
| 109 #endif | |
| 110 }; | |
| 111 | |
| 112 } // mozilla | |
| 113 | |
| 114 #endif // DelayBuffer_h_ |
