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/*
* 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 Computer, 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 <math.h>
#include <wtf/MathExtras.h>
#include <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>
#if OS(DARWIN)
using namespace std;
#endif
namespace WebCore {
// Empirical gain calibration tested across many impulse responses to ensure perceived volume is same as dry (unprocessed) signal
const double GainCalibration = -58.0;
// A minimum power value to when normalizing a silent (or very quiet) impulse response
const double MinPower = 0.000125;
static double calculateNormalizationScale(AudioBus* response)
{
// Normalize by RMS power
size_t numberOfChannels = response->numberOfChannels();
size_t length = response->length();
double power = 0.0;
for (size_t i = 0; i < numberOfChannels; ++i) {
int n = length;
float* p = response->channel(i)->data();
while (n--) {
float sample = *p++;
power += sample * sample;
}
}
power = sqrt(power / (numberOfChannels * length));
// Protect against accidental overload
if (isinf(power) || isnan(power) || power < MinPower)
power = MinPower;
double scale = 1.0 / power;
scale *= pow(10.0, GainCalibration * 0.05); // calibrate to make perceived volume same as unprocessed
// True-stereo compensation
if (response->numberOfChannels() == 4)
scale *= 0.5;
return scale;
}
Reverb::Reverb(AudioBus* impulseResponse, size_t renderSliceSize, size_t maxFFTSize, size_t numberOfChannels, bool useBackgroundThreads)
{
double scale = calculateNormalizationScale(impulseResponse);
if (scale)
impulseResponse->scale(scale);
initialize(impulseResponse, renderSliceSize, maxFFTSize, numberOfChannels, useBackgroundThreads);
// Undo scaling since this shouldn't be a destructive operation on impulseResponse
if (scale)
impulseResponse->scale(1.0 / scale);
}
void Reverb::initialize(AudioBus* impulseResponseBuffer, size_t renderSliceSize, size_t maxFFTSize, size_t numberOfChannels, bool useBackgroundThreads)
{
m_impulseResponseLength = impulseResponseBuffer->length();
// The reverb can handle a mono impulse response and still do stereo processing
size_t numResponseChannels = impulseResponseBuffer->numberOfChannels();
m_convolvers.reserveCapacity(numberOfChannels);
int convolverRenderPhase = 0;
for (size_t i = 0; i < numResponseChannels; ++i) {
AudioChannel* channel = impulseResponseBuffer->channel(i);
OwnPtr<ReverbConvolver> convolver = adoptPtr(new ReverbConvolver(channel, renderSliceSize, maxFFTSize, convolverRenderPhase, useBackgroundThreads));
m_convolvers.append(convolver.release());
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 (numResponseChannels == 4)
m_tempBuffer = new AudioBus(2, MaxFrameSize);
}
void Reverb::process(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.
bool isSafeToProcess = sourceBus && destinationBus && sourceBus->numberOfChannels() > 0 && destinationBus->numberOfChannels() > 0
&& framesToProcess <= MaxFrameSize && framesToProcess <= sourceBus->length() && framesToProcess <= destinationBus->length();
ASSERT(isSafeToProcess);
if (!isSafeToProcess)
return;
// For now only handle mono or stereo output
if (destinationBus->numberOfChannels() > 2) {
destinationBus->zero();
return;
}
AudioChannel* destinationChannelL = destinationBus->channel(0);
AudioChannel* sourceChannelL = sourceBus->channel(0);
// Handle input -> output matrixing...
size_t numInputChannels = sourceBus->numberOfChannels();
size_t numOutputChannels = destinationBus->numberOfChannels();
size_t numReverbChannels = m_convolvers.size();
if (numInputChannels == 2 && numReverbChannels == 2 && numOutputChannels == 2) {
// 2 -> 2 -> 2
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 && numReverbChannels == 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 && numReverbChannels == 1 && numOutputChannels == 2) {
// 1 -> 1 -> 2
m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
// simply copy L -> R
AudioChannel* destinationChannelR = destinationBus->channel(1);
bool isCopySafe = destinationChannelL->data() && destinationChannelR->data() && destinationChannelL->length() >= framesToProcess && destinationChannelR->length() >= framesToProcess;
ASSERT(isCopySafe);
if (!isCopySafe)
return;
memcpy(destinationChannelR->data(), destinationChannelL->data(), sizeof(float) * framesToProcess);
} else if (numInputChannels == 1 && numReverbChannels == 1 && numOutputChannels == 1) {
// 1 -> 1 -> 1
m_convolvers[0]->process(sourceChannelL, destinationChannelL, framesToProcess);
} else if (numInputChannels == 2 && numReverbChannels == 4 && numOutputChannels == 2) {
// 2 -> 4 -> 2 ("True" stereo)
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 && numReverbChannels == 4 && numOutputChannels == 2) {
// 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 {
// Handle gracefully any unexpected / unsupported matrixing
// FIXME: add code for 5.1 support...
destinationBus->zero();
}
}
void Reverb::reset()
{
for (size_t i = 0; i < m_convolvers.size(); ++i)
m_convolvers[i]->reset();
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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