wdsp/rnnr.c

/*	rnnr.c

This file is part of a program that implements a Software-Defined Radio.

This code/file can be found on GitHub : https://github.com/ramdor/Thetis

Copyright (C) 2000-2025 Original authors
Copyright (C) 2020-2025 Richard Samphire MW0LGE

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.

The author can be reached by email at

mw0lge@grange-lane.co.uk

This code is based on code and ideas from  : https://github.com/vu3rdd/wdsp
and and uses RNNoise
https://gitlab.xiph.org/xiph/rnnoise

It uses a non modified version of rmnoise and implements a ringbuffer to handle input/output frame size differences.
*/
//
//============================================================================================//
// Dual-Licensing Statement (Applies Only to Author's Contributions, Richard Samphire MW0LGE) //
// ------------------------------------------------------------------------------------------ //
// For any code originally written by Richard Samphire MW0LGE, or for any modifications		  //
// made by him, the copyright holder for those portions (Richard Samphire) reserves the		  //
// right to use, license, and distribute such code under different terms, including			  //
// closed-source and proprietary licences, in addition to the GNU General Public License	  //
// granted above. Nothing in this statement restricts any rights granted to recipients under  //
// the GNU GPL. Code contributed by others (not Richard Samphire) remains licensed under	  //
// its original terms and is not affected by this dual-licensing statement in any way.		  //
// Richard Samphire can be reached by email at :  mw0lge@grange-lane.co.uk					  //
//============================================================================================//

#define _CRT_SECURE_NO_WARNINGS
#include "comm.h"
#include "rnnoise.h"

static inline float db_to_lin(float db) { return powf(10.0f, db / 20.0f); }
static inline float lin_to_db(float lin) { return 20.0f * log10f(fmaxf(lin, 1e-12f)); }

#define AGC_TARGET_DB	(60.0f)
#define AGC_MIN_DB		(-12.0f)
#define AGC_MAX_DB		(+220.0f)
#define AGC_ATTACK_MS	(10.0f)
#define AGC_RELEASE_MS	(200.0f)
#define AGC_RMS_FLOOR	(1e-6f)
#define SAFETY_CEIL		(30000.0f)

static float agc_alpha_ms(float ms, float frame_hz) {
	const float tc = ms / 1000.0f;
	const float a = expf(-(1.0f / frame_hz) / tc);
	return a < 0.0f ? 0.0f : (a > 1.0f ? 1.0f : a);
}

void rnnr_agc_init(RNNR a)
{
	const float frame_hz = (a->frame_size > 0) ? ((float)a->rate / (float)a->frame_size) : 100.0f;
	a->agc_att_a = agc_alpha_ms(AGC_ATTACK_MS, frame_hz);
	a->agc_rel_a = agc_alpha_ms(AGC_RELEASE_MS, frame_hz);
	a->gain_db = AGC_TARGET_DB;
	a->gain = db_to_lin(a->gain_db);
}

static float frame_rms(const float* x, int n) {
	double s = 0.0;
	for (int i = 0; i < n; i++) { double v = (double)x[i]; s += v * v; }
	float r = (float)sqrt(s / (double)n);
	return (r < AGC_RMS_FLOOR) ? AGC_RMS_FLOOR : r;
}

//used to track RNNR instances
static RNNR* _rnnr_instances = NULL;
static int _rnnr_count = 0;
static int _rnnr_capacity = 0;

// the model to use when creating new RNNR instances
static RNNModel* _rnnr_model = NULL;

//ringbuffer
static void ring_buffer_init(rnnr_ring_buffer* rb, int capacity)
{
	rb->buf = malloc0(capacity * sizeof(float));
	rb->capacity = capacity;
	rb->head = 0;
	rb->tail = 0;
	rb->count = 0;
}

static void ring_buffer_free(rnnr_ring_buffer* rb)
{
	_aligned_free(rb->buf);
	rb->buf = NULL;
	rb->capacity = 0;
	rb->head = rb->tail = rb->count = 0;
}

static void ring_buffer_put(rnnr_ring_buffer* rb, float v)
{
	if (rb->count < rb->capacity)
	{
		rb->buf[rb->tail] = v;
		rb->tail = (rb->tail + 1) % rb->capacity;
		rb->count++;
	}
}

static int ring_buffer_get_bulk(rnnr_ring_buffer* rb, float* dest, int n)
{
	int to_get = n < rb->count ? n : rb->count;
	for (int i = 0; i < to_get; i++)
	{
		dest[i] = rb->buf[rb->head];
		rb->head = (rb->head + 1) % rb->capacity;
	}
	rb->count -= to_get;
	return to_get;
}

static void ring_buffer_resize(rnnr_ring_buffer* rb, int new_capacity)
{
	if (new_capacity == rb->capacity) return;
	float* new_buf = malloc0(new_capacity * sizeof(float));
	int cnt = rb->count;
	for (int i = 0; i < cnt; i++)
	{
		new_buf[i] = rb->buf[(rb->head + i) % rb->capacity];
	}
	_aligned_free(rb->buf);
	rb->buf = new_buf;
	rb->capacity = new_capacity;
	rb->head = 0;
	rb->tail = cnt % new_capacity;
}
//

PORT
void SetRXARNNRRun (int channel, int run)
{
	RNNR a = rxa[channel].rnnr.p;
	if (a->run != run)
	{
		RXAbp1Check (channel, rxa[channel].amd.p->run, rxa[channel].snba.p->run,
							 rxa[channel].emnr.p->run, rxa[channel].anf.p->run, rxa[channel].anr.p->run,
							 run, rxa[channel].sbnr.p->run); // NR3 + NR4 support

		EnterCriticalSection (&ch[channel].csDSP);
		a->run = run;
		RXAbp1Set (channel);
		LeaveCriticalSection (&ch[channel].csDSP);
	}
}

void setSize_rnnr(RNNR a, int size)
{
	_aligned_free(a->output_buffer);
	a->buffer_size = size;
	a->output_buffer = malloc0(a->buffer_size * sizeof(float));

	int new_cap = a->frame_size + a->buffer_size;
	ring_buffer_resize(&a->input_ring, new_cap);
	ring_buffer_resize(&a->output_ring, new_cap);
}

void setBuffers_rnnr(RNNR a, double* in, double* out)
{
	a->in = in;
	a->out = out;
}

void setSamplerate_rnnr(RNNR a, int rate)
{
	a->rate = rate;
	rnnr_agc_init(a);
}

RNNR create_rnnr(int run, int position, int size, double* in, double* out, int rate)
{
	RNNR a = malloc0(sizeof(rnnr));
	InitializeCriticalSection(&a->cs);
	a->run = run;
	a->position = position;
	a->rate = rate; // not used currently, but here for future use
	a->st = rnnoise_create(_rnnr_model);	
	a->frame_size = rnnoise_get_frame_size();
	a->in = in;
	a->out = out;
	a->buffer_size = size;
	rnnr_agc_init(a);

	ring_buffer_init(&a->input_ring, a->frame_size + a->buffer_size);
	ring_buffer_init(&a->output_ring, a->frame_size + a->buffer_size);
	a->to_process_buffer = malloc0(a->frame_size * sizeof(float));
	a->processed_output_buffer = malloc0(a->frame_size * sizeof(float));
	a->output_buffer = malloc0(a->buffer_size * sizeof(float));

	// used to maintain a record of RNNR's here and is used so we can update them all if/when model is changed
	if (_rnnr_count == _rnnr_capacity)
	{
		int new_cap = _rnnr_capacity ? _rnnr_capacity * 2 : 4; // limit number of reallocs by doubling space each time, overkill but that is my middle name ;)
		RNNR* tmp = malloc0(new_cap * sizeof(RNNR));
		memcpy(tmp, _rnnr_instances, _rnnr_count * sizeof(RNNR));
		_aligned_free(_rnnr_instances);
		_rnnr_instances = tmp;
		_rnnr_capacity = new_cap;
	}
	_rnnr_instances[_rnnr_count++] = a;
	//

	return a;
}

void xrnnr(RNNR a, int pos)
{
	if (a->st && a->run && pos == a->position)
	{
		int	 bs = a->buffer_size;
		int	 fs = a->frame_size;
		float* to_process = a->to_process_buffer;
		float* process_out = a->processed_output_buffer;

		EnterCriticalSection(&a->cs);
		for (int i = 0; i < bs; i++)
		{
			ring_buffer_put(&a->input_ring, (float)a->in[2 * i + 0]);

			if (a->input_ring.count >= fs)
			{
				ring_buffer_get_bulk(&a->input_ring, to_process, fs);

				float rms = frame_rms(to_process, fs);
				float cur_db = lin_to_db(rms);
				float desired_db = AGC_TARGET_DB - cur_db;

				float alpha = (desired_db > a->gain_db) ? a->agc_att_a : a->agc_rel_a;
				a->gain_db = alpha * a->gain_db + (1.0f - alpha) * desired_db;
				if (a->gain_db < AGC_MIN_DB) a->gain_db = AGC_MIN_DB;
				if (a->gain_db > AGC_MAX_DB) a->gain_db = AGC_MAX_DB;

				a->gain = db_to_lin(a->gain_db);

				for (int j = 0; j < fs; j++)
				{
					float v = to_process[j] * a->gain;
					if (v > SAFETY_CEIL) v = SAFETY_CEIL;
					if (v < -SAFETY_CEIL) v = -SAFETY_CEIL;
					to_process[j] = v;
				}

				rnnoise_process_frame(a->st, process_out, to_process);

				const float inv = (a->gain > 0.0f) ? (1.0f / a->gain) : 0.0f;
				for (int j = 0; j < fs; j++)
				{
					ring_buffer_put(&a->output_ring, process_out[j] * inv);
				}
			}
		}
		LeaveCriticalSection(&a->cs);

		if (a->output_ring.count >= bs)
		{
			ring_buffer_get_bulk(&a->output_ring, a->output_buffer, bs);
			for (int i = 0; i < bs; i++)
			{
				a->out[2 * i + 0] = (double)a->output_buffer[i];
				a->out[2 * i + 1] = 0;
			}
		}
		else
		{
			memcpy(a->out, a->in, a->buffer_size * sizeof(complex));
		}
	}
	else if (a->out != a->in)
	{
		memcpy(a->out, a->in, a->buffer_size * sizeof(complex));
	}
}

void destroy_rnnr(RNNR a)
{
	// we dont need to maintain order, so just replace with last, and decrement total
	for (int i = 0; i < _rnnr_count; i++)
	{
		if (_rnnr_instances[i] == a)
		{
			_rnnr_instances[i] = _rnnr_instances[--_rnnr_count];
			break;
		}
	}

	EnterCriticalSection(&a->cs);
	rnnoise_destroy(a->st);
	LeaveCriticalSection(&a->cs);
	DeleteCriticalSection(&a->cs);

	_aligned_free(a->to_process_buffer);
	_aligned_free(a->processed_output_buffer);
	_aligned_free(a->output_buffer);
	ring_buffer_free(&a->input_ring);
	ring_buffer_free(&a->output_ring);
	_aligned_free(a);

	// tidy if none now in use
	if (_rnnr_count == 0)
	{
		_aligned_free(_rnnr_instances);
		_rnnr_instances = NULL;
		_rnnr_capacity = 0;
	}
}

PORT
void RNNRloadModel(const char* file_path)
{
	// destroy any in use
	for (int i = 0; i < _rnnr_count; i++)
	{
		RNNR a = _rnnr_instances[i];
		EnterCriticalSection(&a->cs);
		a->run_old = a->run;
		a->run = 0;
		rnnoise_destroy(a->st);
		LeaveCriticalSection(&a->cs);
	}

	// free up any previous loaded model
	if (_rnnr_model)
	{
		rnnoise_model_free(_rnnr_model);
	}

	_rnnr_model = NULL; // default to baked in model

	// try to load
	if (file_path && file_path[0])
	{
		_rnnr_model = rnnoise_model_from_filename(file_path);
	}

	// recreate any we had created previously and restart if needed
	for (int i = 0; i < _rnnr_count; i++)
	{
		RNNR a = _rnnr_instances[i];
		EnterCriticalSection(&a->cs);
		a->st = rnnoise_create(_rnnr_model);
		a->run = a->run_old;
		LeaveCriticalSection(&a->cs);
	}
}

PORT
void SetRXARNNRPosition(int channel, int position)
{
	EnterCriticalSection(&ch[channel].csDSP);
	rxa[channel].rnnr.p->position = position;
	rxa[channel].bp1.p->position = position;
	LeaveCriticalSection(&ch[channel].csDSP);
}