noise_suppressor.cc | Explore in Territory

/*
 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "modules/audio_processing/ns/noise_suppressor.h"

#include <math.h>
#include <stdlib.h>
#include <string.h>

#include <algorithm>

#include "modules/audio_processing/ns/fast_math.h"
#include "rtc_base/checks.h"

namespace webrtc {

namespace {

// Maps sample rate to number of bands.
size_t NumBandsForRate(size_t sample_rate_hz) { … }

// Maximum number of channels for which the channel data is stored on
// the stack. If the number of channels are larger than this, they are stored
// using scratch memory that is pre-allocated on the heap. The reason for this
// partitioning is not to waste heap space for handling the more common numbers
// of channels, while at the same time not limiting the support for higher
// numbers of channels by enforcing the channel data to be stored on the
// stack using a fixed maximum value.
constexpr size_t kMaxNumChannelsOnStack = …;

// Chooses the number of channels to store on the heap when that is required due
// to the number of channels being larger than the pre-defined number
// of channels to store on the stack.
size_t NumChannelsOnHeap(size_t num_channels) { … }

// Hybrib Hanning and flat window for the filterbank.
constexpr std::array<float, 96> kBlocks160w256FirstHalf = …;

// Applies the filterbank window to a buffer.
void ApplyFilterBankWindow(rtc::ArrayView<float, kFftSize> x) { … }

// Extends a frame with previous data.
void FormExtendedFrame(rtc::ArrayView<const float, kNsFrameSize> frame,
                       rtc::ArrayView<float, kFftSize - kNsFrameSize> old_data,
                       rtc::ArrayView<float, kFftSize> extended_frame) { … }

// Uses overlap-and-add to produce an output frame.
void OverlapAndAdd(rtc::ArrayView<const float, kFftSize> extended_frame,
                   rtc::ArrayView<float, kOverlapSize> overlap_memory,
                   rtc::ArrayView<float, kNsFrameSize> output_frame) { … }

// Produces a delayed frame.
void DelaySignal(rtc::ArrayView<const float, kNsFrameSize> frame,
                 rtc::ArrayView<float, kFftSize - kNsFrameSize> delay_buffer,
                 rtc::ArrayView<float, kNsFrameSize> delayed_frame) { … }

// Computes the energy of an extended frame.
float ComputeEnergyOfExtendedFrame(rtc::ArrayView<const float, kFftSize> x) { … }

// Computes the energy of an extended frame based on its subcomponents.
float ComputeEnergyOfExtendedFrame(
    rtc::ArrayView<const float, kNsFrameSize> frame,
    rtc::ArrayView<float, kFftSize - kNsFrameSize> old_data) { … }

// Computes the magnitude spectrum based on an FFT output.
void ComputeMagnitudeSpectrum(
    rtc::ArrayView<const float, kFftSize> real,
    rtc::ArrayView<const float, kFftSize> imag,
    rtc::ArrayView<float, kFftSizeBy2Plus1> signal_spectrum) { … }

// Compute prior and post SNR.
void ComputeSnr(rtc::ArrayView<const float, kFftSizeBy2Plus1> filter,
                rtc::ArrayView<const float> prev_signal_spectrum,
                rtc::ArrayView<const float> signal_spectrum,
                rtc::ArrayView<const float> prev_noise_spectrum,
                rtc::ArrayView<const float> noise_spectrum,
                rtc::ArrayView<float> prior_snr,
                rtc::ArrayView<float> post_snr) { … }

// Computes the attenuating gain for the noise suppression of the upper bands.
float ComputeUpperBandsGain(
    float minimum_attenuating_gain,
    rtc::ArrayView<const float, kFftSizeBy2Plus1> filter,
    rtc::ArrayView<const float> speech_probability,
    rtc::ArrayView<const float, kFftSizeBy2Plus1> prev_analysis_signal_spectrum,
    rtc::ArrayView<const float, kFftSizeBy2Plus1> signal_spectrum) { … }

}  // namespace

NoiseSuppressor::ChannelState::ChannelState(
    const SuppressionParams& suppression_params,
    size_t num_bands)
    : … { … }

NoiseSuppressor::NoiseSuppressor(const NsConfig& config,
                                 size_t sample_rate_hz,
                                 size_t num_channels)
    : … { … }

void NoiseSuppressor::AggregateWienerFilters(
    rtc::ArrayView<float, kFftSizeBy2Plus1> filter) const { … }

void NoiseSuppressor::Analyze(const AudioBuffer& audio) { … }

void NoiseSuppressor::Process(AudioBuffer* audio) { … }

}  // namespace webrtc
chromium/third_party/webrtc/modules/audio_processing/ns/noise_suppressor.cc
