third_party/WebKit/Source/platform/audio/AudioUtilities.h

   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
  30 namespace blink {
  31 namespace AudioUtilities {
  32
  33 // Standard functions for converting to and from decibel values from linear.
  34 PLATFORM_EXPORT float linearToDecibels(float);
  35 PLATFORM_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.
  40 PLATFORM_EXPORT double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate);
  41
  42 // Convert the time to a sample frame at the given sample rate.
  43 PLATFORM_EXPORT size_t timeToSampleFrame(double time, double sampleRate);
  44
  45 // Check that |sampleRate| is a valid rate for AudioBuffers.
  46 PLATFORM_EXPORT bool isValidAudioBufferSampleRate(float sampleRate);
  47
  48 // Return max/min sample rate supported by AudioBuffers.
  49 PLATFORM_EXPORT float minAudioBufferSampleRate();
  50 PLATFORM_EXPORT float maxAudioBufferSampleRate();
  51 } // AudioUtilites
  52 } // namespace blink
  53
  54 #endif // AudioUtilities_h