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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 "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) {
ASSERT(linear >= 0);
return 20 * log10f(linear);
}
double discreteTimeConstantForSampleRate(double timeConstant,
double sampleRate) {
return 1 - exp(-1 / (sampleRate * timeConstant));
}
size_t timeToSampleFrame(double time, double sampleRate) {
ASSERT(time >= 0);
double frame = round(time * sampleRate);
// Just return the largest possible size_t value if necessary.
if (frame >= std::numeric_limits<size_t>::max()) {
return std::numeric_limits<size_t>::max();
}
return static_cast<size_t>(frame);
}
bool isValidAudioBufferSampleRate(float sampleRate) {
return sampleRate >= minAudioBufferSampleRate() &&
sampleRate <= maxAudioBufferSampleRate();
}
float minAudioBufferSampleRate() {
// crbug.com/344375
return 3000;
}
float maxAudioBufferSampleRate() {
// <video> tags support sample rates up 384 kHz so audio context
// should too.
return 384000;
}
bool isPowerOfTwo(size_t x) {
// From Hacker's Delight. x & (x - 1) turns off (zeroes) the
// rightmost 1-bit in the word x. If x is a power of two, then the
// result is, of course, 0.
return x > 0 && ((x & (x - 1)) == 0);
}
} // namespace AudioUtilities
} // namespace blink
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