private/limiter/limiter.h

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/*
 * Copyright (C) 2010-2018 Fons Adriaensen <fons@linuxaudio.org>
 * Copyright (C) 2021 Robin Gareus <robin@gareus.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef _PEAKLIM_H
#define _PEAKLIM_H
 
#include <stdint.h>
 
namespace AudioGrapherDSP {
 
class Limiter
{
public:
        Limiter ();
        ~Limiter ();
 
        void init (float fsamp, int nchan);
        void fini ();
 
        void set_inpgain (float);
        void set_threshold (float);
        void set_release (float);
        void set_truepeak (bool);
 
        int
        get_latency () const
        {
                return _delay;
        }
 
        void
        get_stats (float* peak, float* gmax, float* gmin)
        {
                *peak  = _peak;
                *gmax  = _gmax;
                *gmin  = _gmin;
                _rstat = true;
        }
 
        void process (int nsamp, float const* inp, float* out);
 
private:
        class Histmin
        {
        public:
                void  init (int hlen);
                float write (float v);
                float vmin () { return _vmin; }
 
        private:
                enum {
                        SIZE = 32,
                        MASK = SIZE - 1
                };
 
                int   _hlen;
                int   _hold;
                int   _wind;
                float _vmin;
                float _hist[SIZE];
        };
 
        class Upsampler
        {
        public:
                Upsampler ();
                ~Upsampler ();
 
                void init (int nchan);
                void fini ();
 
                int
                get_latency () const
                {
                        return 23;
                }
 
                float process_one (int chn, float const x);
 
        private:
                int     _nchan;
                float** _z;
        };
 
        float _fsamp;
        int   _nchan;
        bool  _truepeak;
 
        float** _dly_buf;
        float*  _zlf;
 
        int   _delay;
        int   _dly_mask;
        int   _dly_ridx;
        int   _div1, _div2;
        int   _c1, _c2;
        float _g0, _g1, _dg;
        float _gt, _m1, _m2;
        float _w1, _w2, _w3, _wlf;
        float _z1, _z2, _z3;
 
        bool  _rstat;
        float _peak;
        float _gmax;
        float _gmin;
 
        Upsampler _upsampler;
        Histmin   _hist1;
        Histmin   _hist2;
};
 
}
#endif