| /* |
| * 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 |