blob: 84d7eb9d745af36a47c4767e9cfad530db14eeef [file] [log] [blame]
* 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 <string.h> // size_t
#include <memory>
#include "rtc_base/constructormagic.h"
namespace webrtc {
// Forward declarations.
class AudioMultiVector;
class PostDecodeVad;
// This class handles estimation of background noise parameters.
class BackgroundNoise {
// TODO(hlundin): For 48 kHz support, increase kMaxLpcOrder to 10.
// Will work anyway, but probably sound a little worse.
static const size_t kMaxLpcOrder = 8; // 32000 / 8000 + 4.
explicit BackgroundNoise(size_t num_channels);
virtual ~BackgroundNoise();
void Reset();
// Updates the parameter estimates based on the signal currently in the
// |sync_buffer|, and on the latest decision in |vad| if it is running.
void Update(const AudioMultiVector& sync_buffer, const PostDecodeVad& vad);
// Returns |energy_| for |channel|.
int32_t Energy(size_t channel) const;
// Sets the value of |mute_factor_| for |channel| to |value|.
void SetMuteFactor(size_t channel, int16_t value);
// Returns |mute_factor_| for |channel|.
int16_t MuteFactor(size_t channel) const;
// Returns a pointer to |filter_| for |channel|.
const int16_t* Filter(size_t channel) const;
// Returns a pointer to |filter_state_| for |channel|.
const int16_t* FilterState(size_t channel) const;
// Copies |length| elements from |input| to the filter state. Will not copy
// more than |kMaxLpcOrder| elements.
void SetFilterState(size_t channel, const int16_t* input, size_t length);
// Returns |scale_| for |channel|.
int16_t Scale(size_t channel) const;
// Returns |scale_shift_| for |channel|.
int16_t ScaleShift(size_t channel) const;
// Accessors.
bool initialized() const { return initialized_; }
static const int kThresholdIncrement = 229; // 0.0035 in Q16.
static const size_t kVecLen = 256;
static const int kLogVecLen = 8; // log2(kVecLen).
static const size_t kResidualLength = 64;
static const int16_t kLogResidualLength = 6; // log2(kResidualLength)
struct ChannelParameters {
// Constructor.
ChannelParameters() { Reset(); }
void Reset() {
energy = 2500;
max_energy = 0;
energy_update_threshold = 500000;
low_energy_update_threshold = 0;
memset(filter_state, 0, sizeof(filter_state));
memset(filter, 0, sizeof(filter));
filter[0] = 4096;
mute_factor = 0;
scale = 20000;
scale_shift = 24;
int32_t energy;
int32_t max_energy;
int32_t energy_update_threshold;
int32_t low_energy_update_threshold;
int16_t filter_state[kMaxLpcOrder];
int16_t filter[kMaxLpcOrder + 1];
int16_t mute_factor;
int16_t scale;
int16_t scale_shift;
int32_t CalculateAutoCorrelation(const int16_t* signal,
size_t length,
int32_t* auto_correlation) const;
// Increments the energy threshold by a factor 1 + |kThresholdIncrement|.
void IncrementEnergyThreshold(size_t channel, int32_t sample_energy);
// Updates the filter parameters.
void SaveParameters(size_t channel,
const int16_t* lpc_coefficients,
const int16_t* filter_state,
int32_t sample_energy,
int32_t residual_energy);
size_t num_channels_;
std::unique_ptr<ChannelParameters[]> channel_parameters_;
bool initialized_;
} // namespace webrtc