The Tor Browser: content/media/webaudio/WebAudioUtils.h@6474c204b198 (annotated)

content/media/webaudio/WebAudioUtils.h@6474c204b198 (annotated)

content/media/webaudio/WebAudioUtils.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #ifndef WebAudioUtils_h_
 #define WebAudioUtils_h_
 #include <cmath>
 #include <limits>
 #include "mozilla/TypeTraits.h"
 #include "mozilla/FloatingPoint.h"
 #include "MediaSegment.h"
 // Forward declaration
 typedef struct SpeexResamplerState_ SpeexResamplerState;
 namespace mozilla {
 class AudioNodeStream;
 namespace dom {
 class AudioParamTimeline;
 namespace WebAudioUtils {
   // 32 is the minimum required by the spec for createBuffer() and
   // createScriptProcessor() and matches what is used by Blink.  The limit
   // protects against large memory allocations.
   const uint32_t MaxChannelCount = 32;
   // AudioContext::CreateBuffer() "must support sample-rates in at least the
   // range 22050 to 96000."
   const uint32_t MinSampleRate = 8000;
   const uint32_t MaxSampleRate = 192000;
   inline bool FuzzyEqual(float v1, float v2)
   {
     using namespace std;
     return fabsf(v1 - v2) < 1e-7f;
   }
   inline bool FuzzyEqual(double v1, double v2)
   {
     using namespace std;
     return fabs(v1 - v2) < 1e-7;
   }
   /**
    * Computes an exponential smoothing rate for a time based variable
    * over aDuration seconds.
    */
   inline double ComputeSmoothingRate(double aDuration, double aSampleRate)
   {
     return 1.0 - std::exp(-1.0 / (aDuration * aSampleRate));
   }
   /**
    * Converts AudioParamTimeline floating point time values to tick values
    * with respect to a source and a destination AudioNodeStream.
    *
    * This needs to be called for each AudioParamTimeline that gets sent to an
    * AudioNodeEngine on the engine side where the AudioParamTimeline is
    * received.  This means that such engines need to be aware of their source
    * and destination streams as well.
    */
   void ConvertAudioParamToTicks(AudioParamTimeline& aParam,
                                 AudioNodeStream* aSource,
                                 AudioNodeStream* aDest);
   /**
    * Converts a linear value to decibels.  Returns aMinDecibels if the linear
    * value is 0.
    */
   inline float ConvertLinearToDecibels(float aLinearValue, float aMinDecibels)
   {
     return aLinearValue ? 20.0f * std::log10(aLinearValue) : aMinDecibels;
   }
   /**
    * Converts a decibel value to a linear value.
    */
   inline float ConvertDecibelsToLinear(float aDecibels)
   {
     return std::pow(10.0f, 0.05f * aDecibels);
   }
   /**
    * Converts a decibel to a linear value.
    */
   inline float ConvertDecibelToLinear(float aDecibel)
   {
     return std::pow(10.0f, 0.05f * aDecibel);
   }
   inline void FixNaN(double& aDouble)
   {
     if (IsNaN(aDouble) || IsInfinite(aDouble)) {
       aDouble = 0.0;
     }
   }
   inline double DiscreteTimeConstantForSampleRate(double timeConstant, double sampleRate)
   {
     return 1.0 - std::exp(-1.0 / (sampleRate * timeConstant));
   }
   inline bool IsTimeValid(double aTime)
   {
     return aTime >= 0 &&  aTime <= (MEDIA_TIME_MAX >> MEDIA_TIME_FRAC_BITS);
   }
   /**
    * Converts a floating point value to an integral type in a safe and
    * platform agnostic way.  The following program demonstrates the kinds
    * of ways things can go wrong depending on the CPU architecture you're
    * compiling for:
    *
    * #include <stdio.h>
    * volatile float r;
    * int main()
    * {
    *   unsigned int q;
    *   r = 1e100;
    *   q = r;
    *   printf("%f %d\n", r, q);
    *   r = -1e100;
    *   q = r;
    *   printf("%f %d\n", r, q);
    *   r = 1e15;
    *   q = r;
    *   printf("%f %x\n", r, q);
    *   r = 0/0.;
    *   q = r;
    *   printf("%f %d\n", r, q);
    * }
    *
    * This program, when compiled for unsigned int, generates the following
    * results depending on the architecture:
    *
    * x86 and x86-64
    * ---
    *  inf 0
    *  -inf 0
    *  999999995904.000000 -727384064 d4a50000
    *  nan 0
    *
    * ARM
    * ---
    *  inf -1
    *  -inf 0
    *  999999995904.000000 -1
    *  nan 0
    *
    * When compiled for int, this program generates the following results:
    *
    * x86 and x86-64
    * ---
    *  inf -2147483648
    *  -inf -2147483648
    *  999999995904.000000 -2147483648
    *  nan -2147483648
    *
    * ARM
    * ---
    *  inf 2147483647
    *  -inf -2147483648
    *  999999995904.000000 2147483647
    *  nan 0
    *
    * Note that the caller is responsible to make sure that the value
    * passed to this function is not a NaN.  This function will abort if
    * it sees a NaN.
    */
   template <typename IntType, typename FloatType>
   IntType TruncateFloatToInt(FloatType f)
   {
     using namespace std;
     static_assert(mozilla::IsIntegral<IntType>::value == true,
                   "IntType must be an integral type");
     static_assert(mozilla::IsFloatingPoint<FloatType>::value == true,
                   "FloatType must be a floating point type");
     if (f != f) {
       // It is the responsibility of the caller to deal with NaN values.
       // If we ever get to this point, we have a serious bug to fix.
       NS_RUNTIMEABORT("We should never see a NaN here");
     }
     if (f > FloatType(numeric_limits<IntType>::max())) {
       // If the floating point value is outside of the range of maximum
       // integral value for this type, just clamp to the maximum value.
       return numeric_limits<IntType>::max();
     }
     if (f < FloatType(numeric_limits<IntType>::min())) {
       // If the floating point value is outside of the range of minimum
       // integral value for this type, just clamp to the minimum value.
       return numeric_limits<IntType>::min();
     }
     // Otherwise, this conversion must be well defined.
     return IntType(f);
   }
   void Shutdown();
   int
   SpeexResamplerProcess(SpeexResamplerState* aResampler,
                         uint32_t aChannel,
                         const float* aIn, uint32_t* aInLen,
                         float* aOut, uint32_t* aOutLen);
   int
   SpeexResamplerProcess(SpeexResamplerState* aResampler,
                         uint32_t aChannel,
                         const int16_t* aIn, uint32_t* aInLen,
                         float* aOut, uint32_t* aOutLen);
   int
   SpeexResamplerProcess(SpeexResamplerState* aResampler,
                         uint32_t aChannel,
                         const int16_t* aIn, uint32_t* aInLen,
                         int16_t* aOut, uint32_t* aOutLen);
   }
 }
 }
 #endif

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content/media/webaudio/WebAudioUtils.h@6474c204b198 (annotated)

content/media/webaudio/WebAudioUtils.h