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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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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 "platform/audio/AudioUtilities.h"
#include "wtf/Assertions.h"
#include "wtf/MathExtras.h"
namespace blink {
namespace AudioUtilities {
float decibelsToLinear(float decibels)
{
return powf(10, 0.05f * decibels);
}
float linearToDecibels(float linear)
{
// It's not possible to calculate decibels for a zero linear value since it would be -Inf.
// -1000.0 dB represents a very tiny linear value in case we ever reach this case.
ASSERT(linear);
if (!linear)
return -1000;
return 20 * log10f(linear);
}
double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate)
{
return 1 - exp(-1 / (sampleRate * timeConstant));
}
size_t timeToSampleFrame(double time, double sampleRate)
{
return static_cast<size_t>(round(time * sampleRate));
}
bool isValidAudioBufferSampleRate(float sampleRate)
{
return sampleRate >= minAudioBufferSampleRate() && sampleRate <= maxAudioBufferSampleRate();
}
float minAudioBufferSampleRate()
{
// crbug.com/344375
return 3000;
}
float maxAudioBufferSampleRate()
{
// Windows can support audio sampling rates this high, so allow AudioBuffer rates this high as well.
return 192000;
}
} // AudioUtilites
} // namespace blink
#endif // ENABLE(WEB_AUDIO)
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