Source/WebCore/platform/audio/Reverb.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
  *     documentation and/or other materials provided with the distribution.
  * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"

 #if ENABLE(WEB_AUDIO)

 #include "Reverb.h"

 #include "AudioBus.h"
 #include "AudioFileReader.h"
 #include "ReverbConvolver.h"
 #include "VectorMath.h"
 #include <math.h>
 #include <wtf/MathExtras.h>

 namespace WebCore {

 // Empirical gain calibration tested across many impulse responses to ensure perceived volume is same as dry (unprocessed) signal
 constexpr float GainCalibration = -58;
 constexpr float GainCalibrationSampleRate = 44100;

 // A minimum power value to when normalizing a silent (or very quiet) impulse response
 constexpr float MinPower = 0.000125f;

 static float calculateNormalizationScale(AudioBus* response)
 {
     // Normalize by RMS power
     size_t numberOfChannels = response->numberOfChannels();
     size_t length = response->length();

     float power = 0;

     for (size_t i = 0; i < numberOfChannels; ++i)
         power += VectorMath::sumOfSquares(response->channel(i)->data(), length);

     power = sqrt(power / (numberOfChannels * length));

     // Protect against accidental overload
     if (std::isinf(power) || std::isnan(power) || power < MinPower)
         power = MinPower;

     float scale = 1 / power;

     scale *= powf(10, GainCalibration * 0.05f); // calibrate to make perceived volume same as unprocessed

     // Scale depends on sample-rate.
     if (response->sampleRate())
         scale *= GainCalibrationSampleRate / response->sampleRate();

     // True-stereo compensation
     if (response->numberOfChannels() == 4)
         scale *= 0.5f;

     return scale;
 }

 Reverb::Reverb(AudioBus* impulseResponse, size_t renderSliceSize, size_t maxFFTSize, bool useBackgroundThreads, bool normalize)
 {
     float scale = 1;

     if (normalize)
         scale = calculateNormalizationScale(impulseResponse);

     initialize(impulseResponse, renderSliceSize, maxFFTSize, useBackgroundThreads, scale);
 }

 void Reverb::initialize(AudioBus* impulseResponseBuffer, size_t renderSliceSize, size_t maxFFTSize, bool useBackgroundThreads, float scale)
 {
     m_impulseResponseLength = impulseResponseBuffer->length();

     // The reverb can handle a mono impulse response and still do stereo processing
     m_numberOfResponseChannels = impulseResponseBuffer->numberOfChannels();
     unsigned convolverCount = std::max(m_numberOfResponseChannels, 2u);
     m_convolvers.reserveCapacity(convolverCount);

     int convolverRenderPhase = 0;
     for (unsigned i = 0; i < convolverCount; ++i) {
         auto* channel = impulseResponseBuffer->channel(std::min(i, m_numberOfResponseChannels - 1));

         m_convolvers.append(makeUnique<ReverbConvolver>(channel, renderSliceSize, maxFFTSize, convolverRenderPhase, useBackgroundThreads, scale));

         convolverRenderPhase += renderSliceSize;
     }

     // For "True" stereo processing we allocate a temporary buffer to avoid repeatedly allocating it in the process() method.
     // It can be bad to allocate memory in a real-time thread.
     if (m_numberOfResponseChannels == 4)
         m_tempBuffer = AudioBus::create(2, MaxFrameSize);
 }

 void Reverb::process(const AudioBus* sourceBus, AudioBus* destinationBus, size_t framesToProcess)
 {
     // Do a fairly comprehensive sanity check.
     // If these conditions are satisfied, all of the source and destination
     // pointers will be valid for the various matrixing cases.
     ASSERT(sourceBus);
     ASSERT(destinationBus);
     ASSERT(sourceBus->numberOfChannels() > 0u);
     ASSERT(destinationBus->numberOfChannels() > 0u);
     ASSERT(framesToProcess <= MaxFrameSize);
     ASSERT(framesToProcess <= sourceBus->length());
     ASSERT(framesToProcess <= destinationBus->length());

     // For now only handle mono or stereo output
     if (destinationBus->numberOfChannels() > 2) {
         destinationBus->zero();
         return;
     }

     AudioChannel* destinationChannelL = destinationBus->channel(0);
     const AudioChannel* sourceChannelL = sourceBus->channel(0);

     // Handle input -> output matrixing...
     size_t numInputChannels = sourceBus->numberOfChannels();
     size_t numOutputChannels = destinationBus->numberOfChannels();
     size_t numberOfResponseChannels = m_numberOfResponseChannels;

     ASSERT(numInputChannels <= 2ul);
     ASSERT(numOutputChannels <= 2ul);
     ASSERT(numberOfResponseChannels == 1 || numberOfResponseChannels == 2 || numberOfResponseChannels == 4);

     // These are the possible combinations of number inputs, response
     // channels and outputs channels that need to be supported:
     //
     //   numInputChannels:         1 or 2
     //   numberOfResponseChannels: 1, 2, or 4
     //   numOutputChannels:        1 or 2
     //
     // Not all possible combinations are valid. numOutputChannels is
     // one only if both numInputChannels and numberOfResponseChannels are 1.
     // Otherwise numOutputChannels MUST be 2.
     //
     // The valid combinations are
     //
     //   Case     in -> resp -> out
     //   1        1 -> 1 -> 1
     //   2        1 -> 2 -> 2
     //   3        1 -> 4 -> 2
     //   4        2 -> 1 -> 2
     //   5        2 -> 2 -> 2
     //   6        2 -> 4 -> 2

     if (numInputChannels == 2 && (numberOfResponseChannels == 1 || numberOfResponseChannels == 2) && numOutputChannels == 2) {
         // Case 4 and 5: 2 -> 2 -> 2 or 2 -> 1 -> 2.
         //
         // These can be handled in the same way because in the latter
         // case, two connvolvers are still created with the second being a
         // copy of the first.
         const AudioChannel* sourceChannelR = sourceBus->channel(1);
         AudioChannel* destinationChannelR = destinationBus->channel(1);
         m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
         m_convolvers[1]->process(sourceChannelR, destinationChannelR, framesToProcess);
     } else  if (numInputChannels == 1 && numOutputChannels == 2 && numberOfResponseChannels == 2) {
         // Case 2: 1 -> 2 -> 2
         for (int i = 0; i < 2; ++i) {
             AudioChannel* destinationChannel = destinationBus->channel(i);
             m_convolvers[i]->process(sourceChannelL, destinationChannel, framesToProcess);
         }
     } else if (numInputChannels == 1 && numberOfResponseChannels == 1) {
         // Case 1: 1 -> 1 -> 1
         ASSERT(numOutputChannels == 1ul);
         m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
     } else if (numInputChannels == 2 && numberOfResponseChannels == 4 && numOutputChannels == 2) {
         // Case 6: 2 -> 4 -> 2 ("True" stereo)
         const AudioChannel* sourceChannelR = sourceBus->channel(1);
         AudioChannel* destinationChannelR = destinationBus->channel(1);

         AudioChannel* tempChannelL = m_tempBuffer->channel(0);
         AudioChannel* tempChannelR = m_tempBuffer->channel(1);

         // Process left virtual source
         m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
         m_convolvers[1]->process(sourceChannelL, destinationChannelR, framesToProcess);

         // Process right virtual source
         m_convolvers[2]->process(sourceChannelR, tempChannelL, framesToProcess);
         m_convolvers[3]->process(sourceChannelR, tempChannelR, framesToProcess);

         destinationBus->sumFrom(*m_tempBuffer);
     } else if (numInputChannels == 1 && numberOfResponseChannels == 4 && numOutputChannels == 2) {
         // Case 3: 1 -> 4 -> 2 (Processing mono with "True" stereo impulse
         // response) This is an inefficient use of a four-channel impulse
         // response, but we should handle the case.
         AudioChannel* destinationChannelR = destinationBus->channel(1);

         AudioChannel* tempChannelL = m_tempBuffer->channel(0);
         AudioChannel* tempChannelR = m_tempBuffer->channel(1);

         // Process left virtual source
         m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
         m_convolvers[1]->process(sourceChannelL, destinationChannelR, framesToProcess);

         // Process right virtual source
         m_convolvers[2]->process(sourceChannelL, tempChannelL, framesToProcess);
         m_convolvers[3]->process(sourceChannelL, tempChannelR, framesToProcess);

         destinationBus->sumFrom(*m_tempBuffer);
     } else {
         ASSERT_NOT_REACHED();
         destinationBus->zero();
     }
 }

 void Reverb::reset()
 {
     for (size_t i = 0; i < m_convolvers.size(); ++i)
         m_convolvers[i]->reset();
 }

 size_t Reverb::latencyFrames() const
 {
     return !m_convolvers.isEmpty() ? m_convolvers.first()->latencyFrames() : 0;
 }

 } // namespace WebCore

 #endif // ENABLE(WEB_AUDIO)
	/*
	* Copyright (C) 2010 Google Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. Neither the name of Apple Inc. ("Apple") nor the names of
	* its contributors may be used to endorse or promote products derived
	* from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"

	#if ENABLE(WEB_AUDIO)

	#include "Reverb.h"

	#include "AudioBus.h"
	#include "AudioFileReader.h"
	#include "ReverbConvolver.h"
	#include "VectorMath.h"
	#include <math.h>
	#include <wtf/MathExtras.h>

	namespace WebCore {

	// Empirical gain calibration tested across many impulse responses to ensure perceived volume is same as dry (unprocessed) signal
	constexpr float GainCalibration = -58;
	constexpr float GainCalibrationSampleRate = 44100;

	// A minimum power value to when normalizing a silent (or very quiet) impulse response
	constexpr float MinPower = 0.000125f;

	static float calculateNormalizationScale(AudioBus* response)
	{
	// Normalize by RMS power
	size_t numberOfChannels = response->numberOfChannels();
	size_t length = response->length();

	float power = 0;

	for (size_t i = 0; i < numberOfChannels; ++i)
	power += VectorMath::sumOfSquares(response->channel(i)->data(), length);

	power = sqrt(power / (numberOfChannels * length));

	// Protect against accidental overload
	if (std::isinf(power) \|\| std::isnan(power) \|\| power < MinPower)
	power = MinPower;

	float scale = 1 / power;

	scale = powf(10, GainCalibration 0.05f); // calibrate to make perceived volume same as unprocessed

	// Scale depends on sample-rate.
	if (response->sampleRate())
	scale *= GainCalibrationSampleRate / response->sampleRate();

	// True-stereo compensation
	if (response->numberOfChannels() == 4)
	scale *= 0.5f;

	return scale;
	}

	Reverb::Reverb(AudioBus* impulseResponse, size_t renderSliceSize, size_t maxFFTSize, bool useBackgroundThreads, bool normalize)
	{
	float scale = 1;

	if (normalize)
	scale = calculateNormalizationScale(impulseResponse);

	initialize(impulseResponse, renderSliceSize, maxFFTSize, useBackgroundThreads, scale);
	}

	void Reverb::initialize(AudioBus* impulseResponseBuffer, size_t renderSliceSize, size_t maxFFTSize, bool useBackgroundThreads, float scale)
	{
	m_impulseResponseLength = impulseResponseBuffer->length();

	// The reverb can handle a mono impulse response and still do stereo processing
	m_numberOfResponseChannels = impulseResponseBuffer->numberOfChannels();
	unsigned convolverCount = std::max(m_numberOfResponseChannels, 2u);
	m_convolvers.reserveCapacity(convolverCount);

	int convolverRenderPhase = 0;
	for (unsigned i = 0; i < convolverCount; ++i) {
	auto* channel = impulseResponseBuffer->channel(std::min(i, m_numberOfResponseChannels - 1));

	m_convolvers.append(makeUnique<ReverbConvolver>(channel, renderSliceSize, maxFFTSize, convolverRenderPhase, useBackgroundThreads, scale));

	convolverRenderPhase += renderSliceSize;
	}

	// For "True" stereo processing we allocate a temporary buffer to avoid repeatedly allocating it in the process() method.
	// It can be bad to allocate memory in a real-time thread.
	if (m_numberOfResponseChannels == 4)
	m_tempBuffer = AudioBus::create(2, MaxFrameSize);
	}

	void Reverb::process(const AudioBus* sourceBus, AudioBus* destinationBus, size_t framesToProcess)
	{
	// Do a fairly comprehensive sanity check.
	// If these conditions are satisfied, all of the source and destination
	// pointers will be valid for the various matrixing cases.
	ASSERT(sourceBus);
	ASSERT(destinationBus);
	ASSERT(sourceBus->numberOfChannels() > 0u);
	ASSERT(destinationBus->numberOfChannels() > 0u);
	ASSERT(framesToProcess <= MaxFrameSize);
	ASSERT(framesToProcess <= sourceBus->length());
	ASSERT(framesToProcess <= destinationBus->length());

	// For now only handle mono or stereo output
	if (destinationBus->numberOfChannels() > 2) {
	destinationBus->zero();
	return;
	}

	AudioChannel* destinationChannelL = destinationBus->channel(0);
	const AudioChannel* sourceChannelL = sourceBus->channel(0);

	// Handle input -> output matrixing...
	size_t numInputChannels = sourceBus->numberOfChannels();
	size_t numOutputChannels = destinationBus->numberOfChannels();
	size_t numberOfResponseChannels = m_numberOfResponseChannels;

	ASSERT(numInputChannels <= 2ul);
	ASSERT(numOutputChannels <= 2ul);
	ASSERT(numberOfResponseChannels == 1 \|\| numberOfResponseChannels == 2 \|\| numberOfResponseChannels == 4);

	// These are the possible combinations of number inputs, response
	// channels and outputs channels that need to be supported:
	//
	// numInputChannels: 1 or 2
	// numberOfResponseChannels: 1, 2, or 4
	// numOutputChannels: 1 or 2
	//
	// Not all possible combinations are valid. numOutputChannels is
	// one only if both numInputChannels and numberOfResponseChannels are 1.
	// Otherwise numOutputChannels MUST be 2.
	//
	// The valid combinations are
	//
	// Case in -> resp -> out
	// 1 1 -> 1 -> 1
	// 2 1 -> 2 -> 2
	// 3 1 -> 4 -> 2
	// 4 2 -> 1 -> 2
	// 5 2 -> 2 -> 2
	// 6 2 -> 4 -> 2

	if (numInputChannels == 2 && (numberOfResponseChannels == 1 \|\| numberOfResponseChannels == 2) && numOutputChannels == 2) {
	// Case 4 and 5: 2 -> 2 -> 2 or 2 -> 1 -> 2.
	//
	// These can be handled in the same way because in the latter
	// case, two connvolvers are still created with the second being a
	// copy of the first.
	const AudioChannel* sourceChannelR = sourceBus->channel(1);
	AudioChannel* destinationChannelR = destinationBus->channel(1);
	m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
	m_convolvers[1]->process(sourceChannelR, destinationChannelR, framesToProcess);
	} else if (numInputChannels == 1 && numOutputChannels == 2 && numberOfResponseChannels == 2) {
	// Case 2: 1 -> 2 -> 2
	for (int i = 0; i < 2; ++i) {
	AudioChannel* destinationChannel = destinationBus->channel(i);
	m_convolvers[i]->process(sourceChannelL, destinationChannel, framesToProcess);
	}
	} else if (numInputChannels == 1 && numberOfResponseChannels == 1) {
	// Case 1: 1 -> 1 -> 1
	ASSERT(numOutputChannels == 1ul);
	m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
	} else if (numInputChannels == 2 && numberOfResponseChannels == 4 && numOutputChannels == 2) {
	// Case 6: 2 -> 4 -> 2 ("True" stereo)
	const AudioChannel* sourceChannelR = sourceBus->channel(1);
	AudioChannel* destinationChannelR = destinationBus->channel(1);

	AudioChannel* tempChannelL = m_tempBuffer->channel(0);
	AudioChannel* tempChannelR = m_tempBuffer->channel(1);

	// Process left virtual source
	m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
	m_convolvers[1]->process(sourceChannelL, destinationChannelR, framesToProcess);

	// Process right virtual source
	m_convolvers[2]->process(sourceChannelR, tempChannelL, framesToProcess);
	m_convolvers[3]->process(sourceChannelR, tempChannelR, framesToProcess);

	destinationBus->sumFrom(*m_tempBuffer);
	} else if (numInputChannels == 1 && numberOfResponseChannels == 4 && numOutputChannels == 2) {
	// Case 3: 1 -> 4 -> 2 (Processing mono with "True" stereo impulse
	// response) This is an inefficient use of a four-channel impulse
	// response, but we should handle the case.
	AudioChannel* destinationChannelR = destinationBus->channel(1);

	AudioChannel* tempChannelL = m_tempBuffer->channel(0);
	AudioChannel* tempChannelR = m_tempBuffer->channel(1);

	// Process left virtual source
	m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
	m_convolvers[1]->process(sourceChannelL, destinationChannelR, framesToProcess);

	// Process right virtual source
	m_convolvers[2]->process(sourceChannelL, tempChannelL, framesToProcess);
	m_convolvers[3]->process(sourceChannelL, tempChannelR, framesToProcess);

	destinationBus->sumFrom(*m_tempBuffer);
	} else {
	ASSERT_NOT_REACHED();
	destinationBus->zero();
	}
	}

	void Reverb::reset()
	{
	for (size_t i = 0; i < m_convolvers.size(); ++i)
	m_convolvers[i]->reset();
	}

	size_t Reverb::latencyFrames() const
	{
	return !m_convolvers.isEmpty() ? m_convolvers.first()->latencyFrames() : 0;
	}

	} // namespace WebCore

	#endif // ENABLE(WEB_AUDIO)