| /* |
| * 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 "config.h" |
| |
| #if ENABLE(WEB_AUDIO) |
| |
| #include "platform/audio/AudioUtilities.h" |
| #include "wtf/Assertions.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) |