lufs_meter.h

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/*
 * Copyright (C) 2016-2026 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 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 General Public License for more details.
 *
 * You should have received a copy of the GNU 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.
 */
#ifndef _lufs_meter_h_
#define _lufs_meter_h_
 
#include <atomic>
#include <cstdint>
#include <functional>
#include <map>
 
#include "pbd/stack_allocator.h"
#include "pbd/ringbuffer.h"
 
#include "ardour/libardour_visibility.h"
 
namespace ARDOUR {
 
class LIBARDOUR_API LUFSMeter
{
public:
        LUFSMeter (double samplerate, uint32_t n_channels, bool with_hist = false);
        LUFSMeter (LUFSMeter const& other) = delete;
        ~LUFSMeter ();
 
        void run (float const** data, uint32_t n_samples);
        void reset ();
 
        float integrated_loudness () const;
        float momentary () const;
        float max_momentary () const;
        float short_term () const;
        float max_short_term () const;
        float lu_range () const;
        void  lu_range_min_max (float& range_min, float& range_max) const;
        float dbtp ();
        float max_dbtp () const;
 
        struct LUHistory {
                float integrated;
                float short_term;
                float momentary;
        };
 
        size_t hist_read (LUHistory* dest, size_t cnt) {
                return _rb.read (dest, cnt);
        }
 
        size_t hist_read_space () const {
                return _rb.read_space ();
        }
 
        void host_increment_read_idx (size_t cnt) {
                _rb.increment_read_idx (cnt);
        }
 
private:
        void init ();
        void clear ();
 
        float process (float const** data, const uint32_t n_samples, uint32_t offset);
        float sumfrag (uint32_t) const;
 
        void  calc_true_peak (float const** data, const uint32_t n_samples);
        float upsample_x4 (int chn, float const x);
        float upsample_x2 (int chn, float const x);
 
        std::function< float(int, const float) > upsample;
 
        const float _g[5] = { 1.0, 1.0, 1.0, 1.41, 1.41 };
 
        /* config */
        double   _samplerate;
        uint32_t _n_channels;
        uint32_t _n_fragment;
 
        /* filter coeff */
        float _a0, _a1, _a2;
        float _b1, _b2;
        float _c3, _c4;
 
        /* state */
        uint32_t _frag_pos;
        float    _frag_pwr;
        uint32_t _block_cnt;
        float    _block_pwr;
        float    _power[32];
        uint32_t _pow_idx;
        float    _thresh_rel;
        uint32_t _lu_s_div;
 
        float    _momentary_l;
        float    _short_l;
 
        float    _range_min;
        float    _range_max;
 
        float    _maxloudn_M;
        float    _maxloudn_S;
        float    _integrated;
        float    _dbtp;
        float    _max_dbtp;
 
        std::atomic<bool> _rst_dbtp;
        std::atomic<bool> _rst_lufs;
 
#if defined(_MSC_VER)
        typedef std::map<int, uint32_t> History;
#else
        typedef std::map<int, uint32_t, std::less<int>, PBD::StackAllocator<std::pair<const int, uint32_t>, 1000>> History;
#endif
 
        History _hist_m;
        History _hist_s;
 
        std::map<int, float> power_table;
 
        struct FilterState {
                void reset ();
                void sanitize ();
 
                float z1, z2, z3, z4;
        };
 
        FilterState _fst[5];
        float*      _z[5];
 
        bool _lu_history;
 
        PBD::RingBuffer<LUHistory> _rb;
};
 
} // namespace ARDOUR
#endif