/* * 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. */ #ifndef AudioUtilities_h #define AudioUtilities_h #include <cmath> namespace WebCore { namespace AudioUtilities { // https://www.w3.org/TR/webaudio/#render-quantum-size constexpr size_t renderQuantumSize = 128; // Standard functions for converting to and from decibel values from linear. float linearToDecibels(float); float decibelsToLinear(float); // timeConstant is the time it takes a first-order linear time-invariant system // to reach the value 1 - 1/e (around 63.2%) given a step input response. // discreteTimeConstantForSampleRate() will return the discrete time-constant for the specific sampleRate. double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate); // How to do rounding when converting time to sample frame. enum class SampleFrameRounding { Nearest, Down, Up }; // Convert the time to a sample frame at the given sample rate. size_t timeToSampleFrame(double time, double sampleRate, SampleFrameRounding = SampleFrameRounding::Nearest); inline float linearToDecibels(float linear) { ASSERT(linear >= 0); return 20 * log10f(linear); } inline float decibelsToLinear(float decibels) { return powf(10, 0.05f * decibels); } } // AudioUtilites } // WebCore #endif // AudioUtilities_h