path: root/src/replay_gain_state.c

/*
 * Copyright (C) 2003-2010 The Music Player Daemon Project
 * http://www.musicpd.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.
 */

#include "config.h"
#include "replay_gain_state.h"
#include "pcm_volume.h"

#include <glib.h>

#include <assert.h>
#include <math.h>

struct replay_gain_state {
	float preamp, missing_preamp;

	enum replay_gain_mode mode;

	struct replay_gain_info *info;

	float scale;
};

struct replay_gain_state *
replay_gain_state_new(float preamp, float missing_preamp)
{
	struct replay_gain_state *state = g_new(struct replay_gain_state, 1);

	state->preamp = preamp;
	state->missing_preamp = missing_preamp;
	state->mode = REPLAY_GAIN_OFF;
	state->info = NULL;

	return state;
}

void
replay_gain_state_free(struct replay_gain_state *state)
{
	assert(state != NULL);

	if (state->info != NULL)
		replay_gain_info_free(state->info);

	g_free(state);
}

static float
calc_replay_gain_scale(float gain, float peak, float preamp)
{
	float scale;

	if (gain == 0.0)
		return (1);
	scale = pow(10.0, gain / 20.0);
	scale *= preamp;
	if (scale > 15.0)
		scale = 15.0;

	if (scale * peak > 1.0) {
		scale = 1.0 / peak;
	}
	return (scale);
}

static void
replay_gain_state_calc_scale(struct replay_gain_state *state)
{
	assert(state != NULL);

	if (state->mode == REPLAY_GAIN_OFF || state->info == NULL)
		return;

	const struct replay_gain_tuple *tuple =
		&state->info->tuples[state->mode];

	g_debug("computing ReplayGain scale with gain %f, peak %f",
		tuple->gain, tuple->peak);

	state->scale = calc_replay_gain_scale(tuple->gain, tuple->peak,
					      state->preamp);
}

void
replay_gain_state_set_mode(struct replay_gain_state *state,
			   enum replay_gain_mode mode)
{
	assert(state != NULL);

	if (mode == state->mode)
		return;

	state->mode = mode;

	replay_gain_state_calc_scale(state);
}

void
replay_gain_state_set_info(struct replay_gain_state *state,
			   const struct replay_gain_info *info)
{
	assert(state != NULL);

	if (state->info != NULL)
		replay_gain_info_free(state->info);

	state->info = info != NULL
		? replay_gain_info_dup(info)
		: NULL;

	replay_gain_state_calc_scale(state);
}

void
replay_gain_state_apply(const struct replay_gain_state *state,
			void *buffer, size_t size,
			const struct audio_format *format)
{
	assert(state != NULL);

	if (state->mode == REPLAY_GAIN_OFF)
		return;

	float scale = state->info != NULL
		? state->scale : state->missing_preamp;
	pcm_volume(buffer, size, format, pcm_float_to_volume(scale));
}