michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim:set ts=2 sw=2 sts=2 et cindent: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef DelayBuffer_h_
michael@0: #define DelayBuffer_h_
michael@0: 
michael@0: #include "nsTArray.h"
michael@0: #include "AudioSegment.h"
michael@0: #include "mozilla/dom/AudioNodeBinding.h" // for ChannelInterpretation
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: class DelayBuffer {
michael@0:   typedef dom::ChannelInterpretation ChannelInterpretation;
michael@0: 
michael@0: public:
michael@0:   // See WebAudioUtils::ComputeSmoothingRate() for frame to frame exponential
michael@0:   // |smoothingRate| multiplier.
michael@0:   DelayBuffer(double aMaxDelayTicks, double aSmoothingRate)
michael@0:     : mSmoothingRate(aSmoothingRate)
michael@0:     , mCurrentDelay(-1.0)
michael@0:     // Round the maximum delay up to the next tick.
michael@0:     , mMaxDelayTicks(ceil(aMaxDelayTicks))
michael@0:     , mCurrentChunk(0)
michael@0:     // mLastReadChunk is initialized in EnsureBuffer
michael@0: #ifdef DEBUG
michael@0:     , mHaveWrittenBlock(false)
michael@0: #endif
michael@0:   {
michael@0:     // The 180 second limit in AudioContext::CreateDelay() and the
michael@0:     // 1 << MEDIA_TIME_FRAC_BITS limit on sample rate provide a limit on the
michael@0:     // maximum delay.
michael@0:     MOZ_ASSERT(aMaxDelayTicks <=
michael@0:                std::numeric_limits<decltype(mMaxDelayTicks)>::max());
michael@0:   }
michael@0: 
michael@0:   // Write a WEBAUDIO_BLOCK_SIZE block for aChannelCount channels.
michael@0:   void Write(const AudioChunk& aInputChunk);
michael@0: 
michael@0:   // Read a block with an array of delays, in ticks, for each sample frame.
michael@0:   // Each delay should be >= 0 and <= MaxDelayTicks().
michael@0:   void Read(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
michael@0:             AudioChunk* aOutputChunk,
michael@0:             ChannelInterpretation aChannelInterpretation);
michael@0:   // Read a block with a constant delay, which will be smoothed with the
michael@0:   // previous delay.  The delay should be >= 0 and <= MaxDelayTicks().
michael@0:   void Read(double aDelayTicks, AudioChunk* aOutputChunk,
michael@0:             ChannelInterpretation aChannelInterpretation);
michael@0: 
michael@0:   // Read into one of the channels of aOutputChunk, given an array of
michael@0:   // delays in ticks.  This is useful when delays are different on different
michael@0:   // channels.  aOutputChunk must have already been allocated with at least as
michael@0:   // many channels as were in any of the blocks passed to Write().
michael@0:   void ReadChannel(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
michael@0:                    const AudioChunk* aOutputChunk, uint32_t aChannel,
michael@0:                    ChannelInterpretation aChannelInterpretation);
michael@0: 
michael@0:   // Advance the buffer pointer
michael@0:   void NextBlock()
michael@0:   {
michael@0:     mCurrentChunk = (mCurrentChunk + 1) % mChunks.Length();
michael@0: #ifdef DEBUG
michael@0:     MOZ_ASSERT(mHaveWrittenBlock);
michael@0:     mHaveWrittenBlock = false;
michael@0: #endif
michael@0:   }
michael@0: 
michael@0:   void Reset() {
michael@0:     mChunks.Clear();
michael@0:     mCurrentDelay = -1.0;
michael@0:   };
michael@0: 
michael@0:   int MaxDelayTicks() const { return mMaxDelayTicks; }
michael@0: 
michael@0:   size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
michael@0: 
michael@0: private:
michael@0:   void ReadChannels(const double aPerFrameDelays[WEBAUDIO_BLOCK_SIZE],
michael@0:                     const AudioChunk* aOutputChunk,
michael@0:                     uint32_t aFirstChannel, uint32_t aNumChannelsToRead,
michael@0:                     ChannelInterpretation aChannelInterpretation);
michael@0:   bool EnsureBuffer();
michael@0:   int PositionForDelay(int aDelay);
michael@0:   int ChunkForPosition(int aPosition);
michael@0:   int OffsetForPosition(int aPosition);
michael@0:   int ChunkForDelay(int aDelay);
michael@0:   void UpdateUpmixChannels(int aNewReadChunk, uint32_t channelCount,
michael@0:                            ChannelInterpretation aChannelInterpretation);
michael@0: 
michael@0:   // Circular buffer for capturing delayed samples.
michael@0:   FallibleTArray<AudioChunk> mChunks;
michael@0:   // Cache upmixed channel arrays.
michael@0:   nsAutoTArray<const void*,GUESS_AUDIO_CHANNELS> mUpmixChannels;
michael@0:   double mSmoothingRate;
michael@0:   // Current delay, in fractional ticks
michael@0:   double mCurrentDelay;
michael@0:   // Maximum delay, in ticks
michael@0:   int mMaxDelayTicks;
michael@0:   // The current position in the circular buffer.  The next write will be to
michael@0:   // this chunk, and the next read may begin before this chunk.
michael@0:   int mCurrentChunk;
michael@0:   // The chunk owning the pointers in mUpmixChannels
michael@0:   int mLastReadChunk;
michael@0: #ifdef DEBUG
michael@0:   bool mHaveWrittenBlock;
michael@0: #endif
michael@0: };
michael@0: 
michael@0: } // mozilla
michael@0: 
michael@0: #endif // DelayBuffer_h_