cmus/op/mixer_alsa.c

/*
 * Copyright 2008-2013 Various Authors
 * Copyright 2004-2005 Timo Hirvonen
 *
 * 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 "../mixer.h"
#include "../op.h"
#include "../xmalloc.h"
#include "../debug.h"

#include <strings.h>
#include <math.h>

#define ALSA_PCM_NEW_HW_PARAMS_API
#define ALSA_PCM_NEW_SW_PARAMS_API

#include <alsa/asoundlib.h>

static snd_mixer_t *mixer;
static snd_mixer_elem_t *mixer_elem = NULL;

/* configuration */
static char *alsa_mixer_device = NULL;
static char *alsa_mixer_element = NULL;
static int alsa_mixer_mapped_volume = 1;

static int alsa_mixer_init(void)
{
	if (alsa_mixer_device == NULL)
		alsa_mixer_device = xstrdup("default");
	if (alsa_mixer_element == NULL)
		alsa_mixer_element = xstrdup("PCM");
	return 0;
}

static int alsa_mixer_exit(void)
{
	free(alsa_mixer_device);
	alsa_mixer_device = NULL;
	free(alsa_mixer_element);
	alsa_mixer_element = NULL;
	return 0;
}

static snd_mixer_elem_t *find_mixer_elem_by_name(const char *name)
{
	snd_mixer_elem_t *elem;
	snd_mixer_selem_id_t *sid = NULL;
	snd_mixer_selem_id_alloca(&sid);

	if (snd_mixer_selem_id_parse(sid, name))
		return NULL;

	elem = snd_mixer_find_selem(mixer, sid);
	if (!elem) {
		d_print("unable to find simple control '%s',%i\n",
				snd_mixer_selem_id_get_name(sid),
				snd_mixer_selem_id_get_index(sid));
		return NULL;
	}

	if (!snd_mixer_selem_has_playback_volume(elem)) {
		d_print("simple control '%s',%i does not have playback volume\n",
				snd_mixer_selem_id_get_name(sid),
				snd_mixer_selem_id_get_index(sid));
		return NULL;
	}

	return elem;
}

static int alsa_mixer_open(int *volume_max)
{
	snd_mixer_elem_t *elem;
	int rc;

	rc = snd_mixer_open(&mixer, 0);
	if (rc < 0)
		goto error;
	rc = snd_mixer_attach(mixer, alsa_mixer_device);
	if (rc < 0)
		goto error;
	rc = snd_mixer_selem_register(mixer, NULL, NULL);
	if (rc < 0)
		goto error;
	rc = snd_mixer_load(mixer);
	if (rc < 0)
		goto error;

	elem = find_mixer_elem_by_name(alsa_mixer_element);
	if (!elem) {
		d_print("mixer element '%s' not found, trying 'Master'\n",
				alsa_mixer_element);
		elem = find_mixer_elem_by_name("Master");
		if (!elem) {
			d_print("error: cannot find suitable mixer element\n");
			return -2;
		}
	}

	mixer_elem = elem;
	*volume_max = 100;
	return 0;
error:
	d_print("error: %s\n", snd_strerror(rc));
	return -1;
}

static int alsa_mixer_close(void)
{
	snd_mixer_close(mixer);
	return 0;
}

static int alsa_mixer_get_fds(int what, int *fds)
{
	struct pollfd pfd[NR_MIXER_FDS];
	int count, i;

	switch (what) {
	case MIXER_FDS_VOLUME:
		count = snd_mixer_poll_descriptors(mixer, pfd, NR_MIXER_FDS);
		for (i = 0; i < count; i++)
			fds[i] = pfd[i].fd;
		return count;
	default:
		return 0;
	}
}

static void alsa_mixer_get_range(long *min, long *max, int *linear_mapping)
{
	if (!*linear_mapping) {
		int err = snd_mixer_selem_get_playback_dB_range(
				mixer_elem, min, max);
		*linear_mapping = err != 0 || *min >= *max;

		/* Force linear mapping for small ranges of 24 dB */
		enum { max_linear_db_scale = 24 };
		*linear_mapping |= *max - *min <= max_linear_db_scale * 100;
	}
	if (*linear_mapping)
		snd_mixer_selem_get_playback_volume_range(mixer_elem, min, max);
}

static void alsa_mixer_set_vol(snd_mixer_selem_channel_id_t channel,
		long min, long max, int vol, int linear_mapping)
{
	if (linear_mapping) {
		long v = (long)(vol * (max - min) / 100.0 + 0.5) + min;
		snd_mixer_selem_set_playback_volume(mixer_elem, channel, v);
	} else {
		/* alsamixer's volume mapping */
		double norm = vol / 100.0;
		if (min != SND_CTL_TLV_DB_GAIN_MUTE) {
			double min_norm = pow(10, (min - max) / 6000.0);
			norm = norm * (1 - min_norm) + min_norm;
		}
		if (norm <= 0)
			norm = 1e-36;
		long v = (long)(6000.0 * log10(norm) + 0.5) + max;
		snd_mixer_selem_set_playback_dB(mixer_elem, channel, v, 0);
	}
}

static int alsa_mixer_set_volume(int l, int r)
{
	int linear_mapping = !alsa_mixer_mapped_volume;
	long min, max;

	if (!mixer_elem)
		return -1;

	snd_mixer_handle_events(mixer);

	alsa_mixer_get_range(&min, &max, &linear_mapping);

	alsa_mixer_set_vol(SND_MIXER_SCHN_FRONT_LEFT,
			min, max, l, linear_mapping);
	alsa_mixer_set_vol(SND_MIXER_SCHN_FRONT_RIGHT,
			min, max, r, linear_mapping);
	return 0;
}

static int alsa_mixer_get_vol(snd_mixer_selem_channel_id_t channel,
		long min, long max, int linear_mapping)
{
	long val;

	if (linear_mapping) {
		snd_mixer_selem_get_playback_volume(mixer_elem, channel, &val);
		return ((val - min) / (double)(max - min) * 100) + 0.5;
	}

	/* alsamixer's volume mapping */
	snd_mixer_selem_get_playback_dB(mixer_elem, channel, &val);
	double normalized = pow(10, (val - max) / 6000.0);
	if (min != SND_CTL_TLV_DB_GAIN_MUTE) {
		double min_norm = pow(10, (min - max) / 6000.0);
		normalized = (normalized - min_norm) / (1 - min_norm);
	}
	return normalized * 100.0 + 0.5;
}

static int alsa_mixer_get_volume(int *l, int *r)
{
	int linear_mapping = !alsa_mixer_mapped_volume;
	long min, max;

	if (!mixer_elem)
		return -1;

	snd_mixer_handle_events(mixer);

	alsa_mixer_get_range(&min, &max, &linear_mapping);

	*l = alsa_mixer_get_vol(SND_MIXER_SCHN_FRONT_LEFT,
			min, max, linear_mapping);
	*r = alsa_mixer_get_vol(SND_MIXER_SCHN_FRONT_RIGHT,
			min, max, linear_mapping);
	return 0;
}

static int alsa_mixer_set_channel(const char *val)
{
	free(alsa_mixer_element);
	alsa_mixer_element = xstrdup(val);
	return 0;
}

static int alsa_mixer_get_channel(char **val)
{
	if (alsa_mixer_element)
		*val = xstrdup(alsa_mixer_element);
	return 0;
}

static int alsa_mixer_set_device(const char *val)
{
	free(alsa_mixer_device);
	alsa_mixer_device = xstrdup(val);
	return 0;
}

static int alsa_mixer_get_device(char **val)
{
	if (alsa_mixer_device)
		*val = xstrdup(alsa_mixer_device);
	return 0;
}

static int alsa_mixer_set_mapped_volume(const char *val)
{
	alsa_mixer_mapped_volume = atoi(val);
	return 0;
}

static int alsa_mixer_get_mapped_volume(char **val)
{
	*val = alsa_mixer_mapped_volume ? xstrdup("1") : xstrdup("0");
	return 0;
}

const struct mixer_plugin_ops op_mixer_ops = {
	.init = alsa_mixer_init,
	.exit = alsa_mixer_exit,
	.open = alsa_mixer_open,
	.close = alsa_mixer_close,
	.get_fds.abi_2 = alsa_mixer_get_fds,
	.set_volume = alsa_mixer_set_volume,
	.get_volume = alsa_mixer_get_volume,
};

const struct mixer_plugin_opt op_mixer_options[] = {
	OPT(alsa_mixer, channel),
	OPT(alsa_mixer, device),
	OPT(alsa_mixer, mapped_volume),
	{ NULL },
};