87a7b82520
This CL adds proper multichannel support to the noise suppressor. To accomplish that in a safe way, a full refactoring of the noise suppressor code has been done. Due to floating point precision, the changes made are not entirely bitexact. They are, however, very close to being bitexact. As a safety measure, the former noise suppressor code is preserved and a kill-switch is added to allow revering to the legacy noise suppressor in case issues arise. Bug: webrtc:10895, b/143344262 Change-Id: I0b071011b23265ac12e6d4b3956499d122286657 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158407 Commit-Queue: Per Åhgren <peah@webrtc.org> Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org> Cr-Commit-Position: refs/heads/master@{#29646}
85 lines
2.2 KiB
C++
85 lines
2.2 KiB
C++
/*
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* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/ns/fast_math.h"
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#include <math.h>
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#include <stdint.h>
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#include "rtc_base/checks.h"
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namespace webrtc {
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namespace {
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float FastLog2f(float in) {
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RTC_DCHECK_GT(in, .0f);
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// Read and interpret float as uint32_t and then cast to float.
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// This is done to extract the exponent (bits 30 - 23).
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// "Right shift" of the exponent is then performed by multiplying
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// with the constant (1/2^23). Finally, we subtract a constant to
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// remove the bias (https://en.wikipedia.org/wiki/Exponent_bias).
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union {
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float dummy;
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uint32_t a;
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} x = {in};
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float out = x.a;
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out *= 1.1920929e-7f; // 1/2^23
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out -= 126.942695f; // Remove bias.
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return out;
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}
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} // namespace
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float SqrtFastApproximation(float f) {
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// TODO(peah): Add fast approximate implementation.
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return sqrtf(f);
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}
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float Pow2Approximation(float p) {
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// TODO(peah): Add fast approximate implementation.
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return powf(2.f, p);
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}
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float PowApproximation(float x, float p) {
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return Pow2Approximation(p * FastLog2f(x));
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}
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float LogApproximation(float x) {
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constexpr float kLogOf2 = 0.69314718056f;
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return FastLog2f(x) * kLogOf2;
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}
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void LogApproximation(rtc::ArrayView<const float> x, rtc::ArrayView<float> y) {
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for (size_t k = 0; k < x.size(); ++k) {
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y[k] = LogApproximation(x[k]);
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}
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}
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float ExpApproximation(float x) {
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constexpr float kLog10Ofe = 0.4342944819f;
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return PowApproximation(10.f, x * kLog10Ofe);
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}
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void ExpApproximation(rtc::ArrayView<const float> x, rtc::ArrayView<float> y) {
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for (size_t k = 0; k < x.size(); ++k) {
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y[k] = ExpApproximation(x[k]);
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}
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}
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void ExpApproximationSignFlip(rtc::ArrayView<const float> x,
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rtc::ArrayView<float> y) {
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for (size_t k = 0; k < x.size(); ++k) {
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y[k] = ExpApproximation(-x[k]);
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}
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}
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} // namespace webrtc
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