obs-studio/libobs/obs-audio-controls.c

/*
Copyright (C) 2014 by Leonhard Oelke <leonhard@in-verted.de>

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, see <http://www.gnu.org/licenses/>.
*/

#include <math.h>

#include "util/threading.h"
#include "util/bmem.h"
#include "obs.h"
#include "obs-internal.h"

#include "obs-audio-controls.h"

/* These are pointless warnings generated not by our code, but by a standard
 * library macro, INFINITY */
#ifdef _MSC_VER
#pragma warning(disable : 4056)
#pragma warning(disable : 4756)
#endif

typedef float (*obs_fader_conversion_t)(const float val);

struct obs_fader {
	pthread_mutex_t        mutex;
	signal_handler_t       *signals;
	obs_fader_conversion_t def_to_db;
	obs_fader_conversion_t db_to_def;
	obs_source_t           *source;
	enum obs_fader_type    type;
	float                  max_db;
	float                  min_db;
	float                  cur_db;
	bool                   ignore_next_signal;
};

static const char *fader_signals[] = {
	"void volume_changed(ptr fader, float db)",
	NULL
};

static inline float mul_to_db(const float mul)
{
	return (mul == 0.0f) ? -INFINITY : 20.0f * log10f(mul);
}

static inline float db_to_mul(const float db)
{
	return (db == -INFINITY) ? 0.0f : powf(10.0f, db / 20.0f);
}

static float cubic_def_to_db(const float def)
{
	if (def == 1.0f)
		return 0.0f;
	else if (def <= 0.0f)
		return -INFINITY;

	return mul_to_db(def * def * def);
}

static float cubic_db_to_def(const float db)
{
	if (db == 0.0f)
		return 1.0f;
	else if (db == -INFINITY)
		return 0.0f;

	return cbrtf(db_to_mul(db));
}

static void signal_volume_changed(signal_handler_t *sh,
		struct obs_fader *fader, const float db)
{
	struct calldata data;

	calldata_init(&data);

	calldata_set_ptr  (&data, "fader", fader);
	calldata_set_float(&data, "db",    db);

	signal_handler_signal(sh, "volume_changed", &data);

	calldata_free(&data);
}

static void fader_source_volume_changed(void *vptr, calldata_t *calldata)
{
	struct obs_fader *fader = (struct obs_fader *) vptr;

	pthread_mutex_lock(&fader->mutex);

	if (fader->ignore_next_signal) {
		fader->ignore_next_signal = false;
		pthread_mutex_unlock(&fader->mutex);
		return;
	}

	signal_handler_t *sh = fader->signals;
	const float mul      = (float)calldata_float(calldata, "volume");
	const float db       = mul_to_db(mul);
	fader->cur_db        = db;

	pthread_mutex_unlock(&fader->mutex);

	signal_volume_changed(sh, fader, db);
}

static void fader_source_destroyed(void *vptr, calldata_t *calldata)
{
	UNUSED_PARAMETER(calldata);
	struct obs_fader *fader = (struct obs_fader *) vptr;

	obs_fader_detach_source(fader);
}

obs_fader_t *obs_fader_create(enum obs_fader_type type)
{
	struct obs_fader *fader = bzalloc(sizeof(struct obs_fader));
	if (!fader)
		return NULL;

	pthread_mutex_init_value(&fader->mutex);
	if (pthread_mutex_init(&fader->mutex, NULL) != 0)
		goto fail;
	fader->signals = signal_handler_create();
	if (!fader->signals)
		goto fail;
	if (!signal_handler_add_array(fader->signals, fader_signals))
		goto fail;

	switch(type) {
	case OBS_FADER_CUBIC:
		fader->def_to_db = cubic_def_to_db;
		fader->db_to_def = cubic_db_to_def;
		fader->max_db    = 0.0f;
		fader->min_db    = -INFINITY;
		break;
	default:
		goto fail;
		break;
	}
	fader->type = type;

	return fader;
fail:
	obs_fader_destroy(fader);
	return NULL;
}

void obs_fader_destroy(obs_fader_t *fader)
{
	if (!fader)
		return;

	obs_fader_detach_source(fader);
	signal_handler_destroy(fader->signals);
	pthread_mutex_destroy(&fader->mutex);

	bfree(fader);
}

bool obs_fader_set_db(obs_fader_t *fader, const float db)
{
	if (!fader)
		return false;

	pthread_mutex_lock(&fader->mutex);

	bool clamped  = false;
	fader->cur_db = db;

	if (fader->cur_db > fader->max_db) {
		fader->cur_db = fader->max_db;
		clamped       = true;
	}
	if (fader->cur_db < fader->min_db) {
		fader->cur_db = -INFINITY;
		clamped       = true;
	}

	fader->ignore_next_signal = true;
	obs_source_t *src         = fader->source;
	const float mul           = db_to_mul(fader->cur_db);

	pthread_mutex_unlock(&fader->mutex);

	if (src)
		obs_source_set_volume(src, mul);

	return !clamped;
}

float obs_fader_get_db(obs_fader_t *fader)
{
	if (!fader)
		return 0.0f;

	pthread_mutex_lock(&fader->mutex);
	const float db = fader->cur_db;
	pthread_mutex_unlock(&fader->mutex);

	return db;
}

bool obs_fader_set_deflection(obs_fader_t *fader, const float def)
{
	if (!fader)
		return false;

	return obs_fader_set_db(fader, fader->def_to_db(def));
}

float obs_fader_get_deflection(obs_fader_t *fader)
{
	if (!fader)
		return 0.0f;

	pthread_mutex_lock(&fader->mutex);
	const float def = fader->db_to_def(fader->cur_db);
	pthread_mutex_unlock(&fader->mutex);

	return def;
}

bool obs_fader_set_mul(obs_fader_t *fader, const float mul)
{
	if (!fader)
		return false;

	return obs_fader_set_db(fader, mul_to_db(mul));
}

float obs_fader_get_mul(obs_fader_t *fader)
{
	if (!fader)
		return 0.0f;

	pthread_mutex_lock(&fader->mutex);
	const float mul = db_to_mul(fader->cur_db);
	pthread_mutex_unlock(&fader->mutex);

	return mul;
}

bool obs_fader_attach_source(obs_fader_t *fader, obs_source_t *source)
{
	if (!fader || !source)
		return false;

	obs_fader_detach_source(fader);

	pthread_mutex_lock(&fader->mutex);

	signal_handler_t *sh = obs_source_get_signal_handler(source);
	signal_handler_connect(sh, "volume",
			fader_source_volume_changed, fader);
	signal_handler_connect(sh, "destroy",
			fader_source_destroyed, fader);

	fader->source = source;
	fader->cur_db = mul_to_db(obs_source_get_volume(source));

	pthread_mutex_unlock(&fader->mutex);

	return true;
}

void obs_fader_detach_source(obs_fader_t *fader)
{
	if (!fader)
		return;

	pthread_mutex_lock(&fader->mutex);

	if (!fader->source)
		goto exit;

	signal_handler_t *sh = obs_source_get_signal_handler(fader->source);
	signal_handler_disconnect(sh, "volume",
			fader_source_volume_changed, fader);
	signal_handler_disconnect(sh, "destroy",
			fader_source_destroyed, fader);

	fader->source = NULL;

exit:
	pthread_mutex_unlock(&fader->mutex);
}

signal_handler_t *obs_fader_get_signal_handler(obs_fader_t *fader)
{
	return (fader) ? fader->signals : NULL;
}