shaping_clipper.h

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/* Calf DSP plugin pack
 * Distortion-shaping clipper
 *
 * Copyright (C) 2014-2021 Jason Jang
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General
 * Public License along with this program; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */
#include <vector>
#include "pffft.h"
 
class shaping_clipper
{
public:

    shaping_clipper(int sample_rate, int fft_size, float clip_level = 16384);
    ~shaping_clipper();

    void feed(const float* in_smaples, float* out_samples, bool diff_only = false, float* total_margin_shift = NULL);

    int get_feed_size();

    void set_clip_level(float clip_level);

    void set_iterations(int iterations);

    void set_adaptive_distortion_strength(float strength);

    void set_margin_curve(int points[][2], int num_points);
 
private:
    int size;
    int overlap;
    int num_psy_bins;
    PFFFT_Setup* pffft;
    float sample_rate;
    float clip_level;
    float iterations;
    float adaptive_distortion_strength;

    std::vector<float> in_frame, out_dist_frame, margin_curve, window, inv_window, spread_table;

    std::vector<int> spread_table_index;
    std::vector<std::pair<int, int>> spread_table_range;

    void generate_hann_window();

    void generate_spread_table();

    void apply_window(const float* in_frame, float* out_frame, const bool add_to_out_frame = false);

    void clip_to_window(const float* windowed_frame, float* clipping_delta, float delta_boost = 1.0);

    void calculate_mask_curve(const float* spectrum, float* mask_curve);

    void limit_clip_spectrum(float* clip_spectrum, const float* mask_curve);
 
};