AudioUtilities.cpp   [plain text]

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
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 *
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "AudioUtilities.h"
#include <wtf/MathExtras.h>

namespace WebCore {

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));
}
} // AudioUtilites

} // WebCore

#endif // ENABLE(WEB_AUDIO)