dynamics_compressor.cc | Explore in Territory

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 * 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.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "third_party/blink/renderer/platform/audio/dynamics_compressor.h"

#include <algorithm>
#include <cmath>

#include "base/logging.h"
#include "base/notreached.h"
#include "third_party/blink/renderer/platform/audio/audio_bus.h"
#include "third_party/blink/renderer/platform/audio/audio_utilities.h"
#include "third_party/blink/renderer/platform/audio/denormal_disabler.h"
#include "third_party/blink/renderer/platform/wtf/math_extras.h"
#include "third_party/fdlibm/ieee754.h"

namespace blink {

namespace {

// Metering hits peaks instantly, but releases this fast (in seconds).
constexpr float kMeteringReleaseTimeConstant = …;

constexpr float kUninitializedValue = …;

constexpr float kPreDelay = …;  // seconds

// Release zone values 0 -> 1.
constexpr float kReleaseZone1 = …;
constexpr float kReleaseZone2 = …;
constexpr float kReleaseZone3 = …;
constexpr float kReleaseZone4 = …;

constexpr float kABase = …;
constexpr float kBBase = …;
constexpr float kCBase = …;
constexpr float kDBase = …;
constexpr float kEBase = …;

// Detector release time.
constexpr float kSatReleaseTime = …;

// Returns x if x is finite (not NaN or infinite), otherwise returns
// default_value
float EnsureFinite(float x, float default_value) { … }

}  // namespace

DynamicsCompressor::DynamicsCompressor(float sample_rate,
                                       unsigned number_of_channels)
    : … { … }

void DynamicsCompressor::Process(const AudioBus* source_bus,
                                 AudioBus* destination_bus,
                                 unsigned frames_to_process) { … }

void DynamicsCompressor::Reset() { … }

void DynamicsCompressor::SetNumberOfChannels(unsigned number_of_channels) { … }

void DynamicsCompressor::SetParameterValue(unsigned parameter_id, float value) { … }

float DynamicsCompressor::ParameterValue(unsigned parameter_id) const { … }

float DynamicsCompressor::SampleRate() const { … }

float DynamicsCompressor::Nyquist() const { … }

double DynamicsCompressor::TailTime() const { … }

double DynamicsCompressor::LatencyTime() const { … }

bool DynamicsCompressor::RequiresTailProcessing() const { … }

void DynamicsCompressor::InitializeParameters() { … }

void DynamicsCompressor::SetPreDelayTime(float pre_delay_time) { … }

// Exponential curve for the knee.
// It is 1st derivative matched at linear_threshold_ and asymptotically
// approaches the value linear_threshold_ + 1 / k.
float DynamicsCompressor::KneeCurve(float x, float k) const { … }

// Full compression curve with constant ratio after knee.
float DynamicsCompressor::Saturate(float x, float k) const { … }

float DynamicsCompressor::KAtSlope(float desired_slope) const { … }

float DynamicsCompressor::UpdateStaticCurveParameters(float db_threshold,
                                                      float db_knee,
                                                      float ratio) { … }

}  // namespace blink
chromium/third_party/blink/renderer/platform/audio/dynamics_compressor.cc
