1/* 2 * Copyright (C) 2010, Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY 17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25#ifndef AudioUtilities_h 26#define AudioUtilities_h 27 28#include "platform/PlatformExport.h" 29 30namespace blink { 31namespace AudioUtilities { 32 33// Standard functions for converting to and from decibel values from linear. 34PLATFORM_EXPORT float linearToDecibels(float); 35PLATFORM_EXPORT float decibelsToLinear(float); 36 37// timeConstant is the time it takes a first-order linear time-invariant system 38// to reach the value 1 - 1/e (around 63.2%) given a step input response. 39// discreteTimeConstantForSampleRate() will return the discrete time-constant for the specific sampleRate. 40PLATFORM_EXPORT double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate); 41 42// Convert the time to a sample frame at the given sample rate. 43PLATFORM_EXPORT size_t timeToSampleFrame(double time, double sampleRate); 44 45// Check that |sampleRate| is a valid rate for AudioBuffers. 46PLATFORM_EXPORT bool isValidAudioBufferSampleRate(float sampleRate); 47 48// Return max/min sample rate supported by AudioBuffers. 49PLATFORM_EXPORT float minAudioBufferSampleRate(); 50PLATFORM_EXPORT float maxAudioBufferSampleRate(); 51} // AudioUtilites 52} // namespace blink 53 54#endif // AudioUtilities_h 55