115 lines
4.3 KiB
C
115 lines
4.3 KiB
C
/*
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libspecbleach - A spectral processing library
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Copyright 2022 Luciano Dato <lucianodato@gmail.com>
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef SPECBLEACH_ADENOISER_H_INCLUDED
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#define SPECBLEACH_ADENOISER_H_INCLUDED
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stdbool.h>
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#include <stdint.h>
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typedef void* SpectralBleachHandle;
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typedef struct SpectralBleachAdaptiveParameters {
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/* Enables outputting the residue of the reduction processing. It's either
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* true or false */
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bool residual_listen;
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/* Sets the amount of dBs that the noise will be attenuated. It goes from 0 dB
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* to 40 dB. This controls both the gain attenuation strength and the residual
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* noise mixing level for optimal noise reduction. */
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float reduction_amount;
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/* Percentage of smoothing to apply. Averages the reduction calculation frame
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* per frame so the rate of change is less resulting in less musical noise but
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* if too strong it can blur transient and reduce high frequencies. It goes
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* from 0 to 100 percent */
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float smoothing_factor;
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/* Percentage of whitening that is going to be applied to the residue of the
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* reduction. It modifies the noise floor to be more like white noise. This
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* can help hide musical noise when the noise is colored. It goes from 0 to
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* 100 percent */
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float whitening_factor;
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/* Type of algorithm used to scale noise in order to apply over or under
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* subtraction in different parts of the spectrum while calculating the
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* reduction. 0 is a-posteriori snr scaling using the complete spectrum, 1 is
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* a-posteriori using critical bands, 2 is using masking thresholds and 3 is
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* disabled.
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*/
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int noise_scaling_type;
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/* Strength in which the reduction will be applied. It uses the masking
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* thresholds of the signal to determine where in the spectrum the reduction
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* needs to be stronger. This parameter scales how much in each of the
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* frequencies the reduction is going to be applied. It can be a positive dB
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* value in between 0 dB and 12 dB */
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float noise_rescale;
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/* Sets the SNR threshold in dB in which the post-filter will start to blur
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* musical noise. It can be a positive or negative dB value in between -10 dB
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* and 10 dB */
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float post_filter_threshold;
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/* Method used for adaptive noise estimation in the adaptive denoiser.
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* 0: LOUIZOU_METHOD uses minimum statistics (default)
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* 1: SPP_MMSE_METHOD uses Speech Presence Probability with MMSE estimation
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* for lower complexity and unbiased noise tracking. */
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int noise_estimation_method;
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} SpectralBleachAdaptiveParameters;
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/**
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* Returns a handle to an instance of the library for the adaptive based
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* noise reduction. Sample rate could be anything from 4000hz to 192khz.
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* Recommended frame size range is between 20ms and 100ms
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*/
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SpectralBleachHandle specbleach_adaptive_initialize(uint32_t sample_rate,
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float frame_size);
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/**
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* Free instance associated to the handle passed
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*/
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void specbleach_adaptive_free(SpectralBleachHandle instance);
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/**
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* Loads the parameters for the reduction.
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* This has to be called before processing
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*/
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bool specbleach_adaptive_load_parameters(
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SpectralBleachHandle instance, SpectralBleachAdaptiveParameters parameters);
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/**
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* Returns the latency in samples associated with the library instance
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*/
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uint32_t specbleach_adaptive_get_latency(SpectralBleachHandle instance);
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/**
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* Process buffer of a number of samples
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*/
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bool specbleach_adaptive_process(SpectralBleachHandle instance,
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uint32_t number_of_samples, const float* input,
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float* output);
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#ifdef __cplusplus
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}
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#endif
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#endif
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