content/media/webaudio/DelayBuffer.h@b8a032363ba2 (annotated)
content/media/webaudio/DelayBuffer.h
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| michael@0 | 2 | /* vim:set ts=2 sw=2 sts=2 et cindent: */ |
| michael@0 | 3 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 4 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 5 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 6 | |
| michael@0 | 7 | #ifndef DelayBuffer_h_ |
| michael@0 | 8 | #define DelayBuffer_h_ |
| michael@0 | 9 | |
| michael@0 | 10 | #include "nsTArray.h" |
| michael@0 | 11 | #include "AudioSegment.h" |
| michael@0 | 12 | #include "mozilla/dom/AudioNodeBinding.h" // for ChannelInterpretation |
| michael@0 | 13 | |
| michael@0 | 14 | namespace mozilla { |
| michael@0 | 15 | |
| michael@0 | 16 | class DelayBuffer { |
| michael@0 | 17 | typedef dom::ChannelInterpretation ChannelInterpretation; |
| michael@0 | 18 | |
| michael@0 | 19 | public: |
| michael@0 | 20 | // See WebAudioUtils::ComputeSmoothingRate() for frame to frame exponential |
| michael@0 | 21 | // |smoothingRate| multiplier. |
| michael@0 | 22 | DelayBuffer(double aMaxDelayTicks, double aSmoothingRate) |
| michael@0 | 23 | : mSmoothingRate(aSmoothingRate) |
| michael@0 | 24 | , mCurrentDelay(-1.0) |
| michael@0 | 25 | // Round the maximum delay up to the next tick. |
| michael@0 | 26 | , mMaxDelayTicks(ceil(aMaxDelayTicks)) |
| michael@0 | 27 | , mCurrentChunk(0) |
| michael@0 | 28 | // mLastReadChunk is initialized in EnsureBuffer |
| michael@0 | 29 | #ifdef DEBUG |
| michael@0 | 30 | , mHaveWrittenBlock(false) |
| michael@0 | 31 | #endif |
| michael@0 | 32 | { |
| michael@0 | 33 | // The 180 second limit in AudioContext::CreateDelay() and the |
| michael@0 | 34 | // 1 << MEDIA_TIME_FRAC_BITS limit on sample rate provide a limit on the |
| michael@0 | 35 | // maximum delay. |
| michael@0 | 36 | MOZ_ASSERT(aMaxDelayTicks <= |
| michael@0 | 37 | std::numeric_limits<decltype(mMaxDelayTicks)>::max()); |
| michael@0 | 38 | } |
| michael@0 | 39 | |
| michael@0 | 40 | // Write a WEBAUDIO_BLOCK_SIZE block for aChannelCount channels. |
| michael@0 | 41 | void Write(const AudioChunk& aInputChunk); |
| michael@0 | 42 | |
| michael@0 | 43 | // Read a block with an array of delays, in ticks, for each sample frame. |
| michael@0 | 44 | // Each delay should be >= 0 and <= MaxDelayTicks(). |
| michael@0 | 45 | void Read(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], |
| michael@0 | 46 | AudioChunk* aOutputChunk, |
| michael@0 | 47 | ChannelInterpretation aChannelInterpretation); |
| michael@0 | 48 | // Read a block with a constant delay, which will be smoothed with the |
| michael@0 | 49 | // previous delay. The delay should be >= 0 and <= MaxDelayTicks(). |
| michael@0 | 50 | void Read(double aDelayTicks, AudioChunk* aOutputChunk, |
| michael@0 | 51 | ChannelInterpretation aChannelInterpretation); |
| michael@0 | 52 | |
| michael@0 | 53 | // Read into one of the channels of aOutputChunk, given an array of |
| michael@0 | 54 | // delays in ticks. This is useful when delays are different on different |
| michael@0 | 55 | // channels. aOutputChunk must have already been allocated with at least as |
| michael@0 | 56 | // many channels as were in any of the blocks passed to Write(). |
| michael@0 | 57 | void ReadChannel(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], |
| michael@0 | 58 | const AudioChunk* aOutputChunk, uint32_t aChannel, |
| michael@0 | 59 | ChannelInterpretation aChannelInterpretation); |
| michael@0 | 60 | |
| michael@0 | 61 | // Advance the buffer pointer |
| michael@0 | 62 | void NextBlock() |
| michael@0 | 63 | { |
| michael@0 | 64 | mCurrentChunk = (mCurrentChunk + 1) % mChunks.Length(); |
| michael@0 | 65 | #ifdef DEBUG |
| michael@0 | 66 | MOZ_ASSERT(mHaveWrittenBlock); |
| michael@0 | 67 | mHaveWrittenBlock = false; |
| michael@0 | 68 | #endif |
| michael@0 | 69 | } |
| michael@0 | 70 | |
| michael@0 | 71 | void Reset() { |
| michael@0 | 72 | mChunks.Clear(); |
| michael@0 | 73 | mCurrentDelay = -1.0; |
| michael@0 | 74 | }; |
| michael@0 | 75 | |
| michael@0 | 76 | int MaxDelayTicks() const { return mMaxDelayTicks; } |
| michael@0 | 77 | |
| michael@0 | 78 | size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const; |
| michael@0 | 79 | |
| michael@0 | 80 | private: |
| michael@0 | 81 | void ReadChannels(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE], |
| michael@0 | 82 | const AudioChunk* aOutputChunk, |
| michael@0 | 83 | uint32_t aFirstChannel, uint32_t aNumChannelsToRead, |
| michael@0 | 84 | ChannelInterpretation aChannelInterpretation); |
| michael@0 | 85 | bool EnsureBuffer(); |
| michael@0 | 86 | int PositionForDelay(int aDelay); |
| michael@0 | 87 | int ChunkForPosition(int aPosition); |
| michael@0 | 88 | int OffsetForPosition(int aPosition); |
| michael@0 | 89 | int ChunkForDelay(int aDelay); |
| michael@0 | 90 | void UpdateUpmixChannels(int aNewReadChunk, uint32_t channelCount, |
| michael@0 | 91 | ChannelInterpretation aChannelInterpretation); |
| michael@0 | 92 | |
| michael@0 | 93 | // Circular buffer for capturing delayed samples. |
| michael@0 | 94 | FallibleTArray<AudioChunk> mChunks; |
| michael@0 | 95 | // Cache upmixed channel arrays. |
| michael@0 | 96 | nsAutoTArray<const void*,GUESS_AUDIO_CHANNELS> mUpmixChannels; |
| michael@0 | 97 | double mSmoothingRate; |
| michael@0 | 98 | // Current delay, in fractional ticks |
| michael@0 | 99 | double mCurrentDelay; |
| michael@0 | 100 | // Maximum delay, in ticks |
| michael@0 | 101 | int mMaxDelayTicks; |
| michael@0 | 102 | // The current position in the circular buffer. The next write will be to |
| michael@0 | 103 | // this chunk, and the next read may begin before this chunk. |
| michael@0 | 104 | int mCurrentChunk; |
| michael@0 | 105 | // The chunk owning the pointers in mUpmixChannels |
| michael@0 | 106 | int mLastReadChunk; |
| michael@0 | 107 | #ifdef DEBUG |
| michael@0 | 108 | bool mHaveWrittenBlock; |
| michael@0 | 109 | #endif |
| michael@0 | 110 | }; |
| michael@0 | 111 | |
| michael@0 | 112 | } // mozilla |
| michael@0 | 113 | |
| michael@0 | 114 | #endif // DelayBuffer_h_ |
