Moving mixers to audio outputs

NEWS

 ver 0.15 - (200?/??/??)
+* Rewritten mixer code to support multiple mixers
 * Add audio archive extraction support:
   - bzip2
   - iso9660

doc/mpd.conf.5

@@ -157,18 +157,23 @@ Linear interpolator, very fast, poor quality.
 For an up-to-date list of available converters, please see the libsamplerate
 documentation (available online at <\fBhttp://www.mega-nerd.com/SRC/\fP>).
 .TP
-.B mixer_type <oss, alsa or software>
-This specifies which mixer to use.  The default depends on what audio output
-support mpd was built with.
+.B mixer_type <alsa, oss, software or hardware>
+This specifies which mixer to use.  The default is hardware and depends on
+what audio output support mpd was built with. Options alsa and oss are
+legacy and should not be used in new configs, but when set mixer_device
+and mixer_control will apply.
 .TP
 .B mixer_device <mixer dev>
 This specifies which mixer to use.  The default for oss is "/dev/mixer"; the
-default for alsa is "default".
+default for alsa is "default". This option is deprecated and should not be
+used.  Look at the mix_device option of corresponding output device instead.
 .TP
 .B mixer_control <mixer ctrl>
 This specifies which mixer control to use (sometimes referred to as the
 "device").  Examples of mixer controls are PCM, Line1, Master, etc.  An example
-for OSS is "Pcm", and an example for alsa is "PCM".
+for OSS is "Pcm", and an example for alsa is "PCM". This option is deprecated
+and should not be used. Look at the mix_control option of corresponding
+output device instead.
 .TP
 .B replaygain <album or track>
 If specified, mpd will adjust the volume of songs played using ReplayGain tags
@@ -276,6 +281,15 @@ whatever audio format is passed to the audio output.
 .B device <dev>
 This specifies the device to use for audio output.  The default is "default".
 .TP
+.B mix_device <mixer dev>
+This specifies which mixer to use.  The default for oss is "/dev/mixer"; the
+default for alsa is "default".
+.TP
+.B mix_control <mixer ctrl>
+This specifies which mixer control to use (sometimes referred to as the
+"device").  Examples of mixer controls are PCM, Line1, Master, etc.  An example
+for OSS is "Pcm", and an example for alsa is "PCM".
+.TP
 .B use_mmap <yes or no>
 Setting this allows you to use memory-mapped I/O.  Certain hardware setups may
 benefit from this, but most do not.  Most users do not need to set this.  The

doc/mpdconf.example

@@ -162,6 +162,8 @@ log_file			"~/.mpd/log"
 #	name			"My ALSA Device"
 #	device			"hw:0,0"	# optional
 #	format			"44100:16:2"	# optional
+#	mix_device		"default"	# optional
+#	mix_control		"PCM"		# optional
 #}
 #
 # An example of an OSS output:
@@ -171,6 +173,8 @@ log_file			"~/.mpd/log"
 #	name			"My OSS Device"
 #	device			"/dev/dsp"	# optional
 #	format			"44100:16:2"	# optional
+#	mix_device		"/dev/mixer"	# optional
+#	mix_control		"PCM"		# optional
 #}
 #
 # An example of a shout output (for streaming to Icecast):
@@ -232,17 +236,9 @@ log_file			"~/.mpd/log"
 # specified it may be autodetected at startup, depending on the dependencies
 # which were compiled into the server.
 #
-# An example for controlling an ALSA mixer:
+# An example for controlling an ALSA or OSS mixer:
 #
-#mixer_type			"alsa"
-#mixer_device			"default"
-#mixer_control			"PCM"
-#
-# An example for controlling an OSS mixer:
-#
-#mixer_type			"oss"
-#mixer_device			"/dev/mixer"
-#mixer_control			"PCM"
+#mixer_type			"hardware"
 #
 # This example is a general volume control mixer, it is used to adjust the 
 # volume of the audio sent to the audio output, and will work with all outputs.

src/Makefile.am

@@ -273,6 +273,7 @@ endif
 
 if HAVE_ALSA
 mpd_SOURCES += output/alsa_plugin.c
+mpd_SOURCES += mixer/alsa_mixer.c
 endif
 
 if HAVE_AO
@@ -293,6 +294,7 @@ endif
 
 if HAVE_OSS
 mpd_SOURCES += output/oss_plugin.c
+mpd_SOURCES += mixer/oss_mixer.c
 endif
 
 if HAVE_OSX
@@ -315,7 +317,6 @@ if HAVE_SHOUT_OGG
 mpd_SOURCES += output/shout_ogg.c
 endif
 
-
 mpd_CFLAGS = $(MPD_CFLAGS)
 mpd_CPPFLAGS = \
 	$(CURL_CFLAGS) \

src/audio.c

@@ -25,6 +25,7 @@
 #include "client.h"
 #include "idle.h"
 #include "utils.h"
+#include "mixer.h"
 
 #include <glib.h>
 
@@ -428,3 +429,57 @@ errline:
 	}
 }
 
+bool mixer_control_setvol(unsigned int device, int volume, int rel)
+{
+	struct audio_output *output;
+	if (device >= audioOutputArraySize)
+		return false;
+
+	output = &audioOutputArray[device];
+	if (output->plugin && output->plugin->control) {
+		if (rel) {
+			int cur_volume;
+			if (!output->plugin->control(output->data, AC_MIXER_GETVOL, &cur_volume)) {
+				return false;
+			}
+			volume = volume + cur_volume;
+		}
+		if (volume > 100)
+			volume = 100;
+		else if (volume < 0)
+			volume = 0;
+
+		return output->plugin->control(output->data, AC_MIXER_SETVOL, &volume);
+	}
+	return false;
+}
+
+bool mixer_control_getvol(unsigned int device, int *volume)
+{
+	struct audio_output *output;
+	if (device >= audioOutputArraySize)
+		return false;
+
+	output = &audioOutputArray[device];
+	if (output->plugin && output->plugin->control) {
+		return output->plugin->control(output->data, AC_MIXER_GETVOL, volume);
+	}
+	return false;
+}
+
+bool mixer_configure_legacy(char *name, ConfigParam *param)
+{
+	unsigned i;
+	struct audio_output *output;
+
+	for (i = 0; i < audioOutputArraySize; ++i) {
+		output = &audioOutputArray[i];
+		if (output && output->plugin && !strcmp(name, output->plugin->name)) {
+			if (output->plugin->control) {
+				g_debug("reconfiguring %s mixer\n", name);
+				return output->plugin->control(output->data, AC_MIXER_CONFIGURE, param);
+			}
+		}
+	}
+	return false;
+}

src/audio.h

@@ -21,6 +21,7 @@
 
 #include <stdbool.h>
 #include <stdio.h>
+#include "conf.h"
 
 #define AUDIO_AO_DRIVER_DEFAULT	"default"
 
@@ -70,4 +71,8 @@ void readAudioDevicesState(FILE *fp);
 
 void saveAudioDevicesState(FILE *fp);
 
+bool mixer_control_setvol(unsigned int device, int volume, int rel);
+bool mixer_control_getvol(unsigned int device, int *volume);
+bool mixer_configure_legacy(char *name, ConfigParam *param);
+
 #endif

src/command.c

@@ -388,7 +388,7 @@ handle_status(struct client *client,
 		      COMMAND_STATUS_PLAYLIST_LENGTH ": %i\n"
 		      COMMAND_STATUS_CROSSFADE ": %i\n"
 		      COMMAND_STATUS_STATE ": %s\n",
-		      getVolumeLevel(),
+		      volume_level_get(),
 		      getPlaylistRepeatStatus(),
 		      getPlaylistRandomStatus(),
 		      getPlaylistVersion(),
@@ -906,7 +906,7 @@ handle_volume(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 	if (!check_int(client, &change, argv[1], need_integer))
 		return COMMAND_RETURN_ERROR;
 
-	ret = changeVolumeLevel(change, 1);
+	ret = volume_level_change(change, 1);
 	if (ret == -1)
 		command_error(client, ACK_ERROR_SYSTEM,
 			      "problems setting volume");
@@ -922,7 +922,7 @@ handle_setvol(struct client *client, G_GNUC_UNUSED int argc, char *argv[])
 	if (!check_int(client, &level, argv[1], need_integer))
 		return COMMAND_RETURN_ERROR;
 
-	ret = changeVolumeLevel(level, 0);
+	ret = volume_level_change(level, 0);
 	if (ret == -1)
 		command_error(client, ACK_ERROR_SYSTEM,
 			      "problems setting volume");

src/main.c

@@ -264,7 +264,7 @@ int main(int argc, char *argv[])
 	dc_init();
 	initAudioConfig();
 	initAudioDriver();
-	initVolume();
+	volume_init();
 	client_manager_init();
 	replay_gain_global_init();
 	initNormalization();
@@ -278,7 +278,6 @@ int main(int argc, char *argv[])
 
 	initZeroconf();
 
-	openVolumeDevice();
 	decoder_thread_start();
 	player_create();
 	read_state_file();
@@ -315,7 +314,7 @@ int main(int argc, char *argv[])
 	finishNormalization();
 	finishAudioDriver();
 	finishAudioConfig();
-	finishVolume();
+	volume_finish();
 	mapper_finish();
 	path_global_finish();
 	finishPermissions();

src/mixer.h

+
+#ifndef MPD_MIXER_H
+#define MPD_MIXER_H
+
+#include "conf.h"
+
+/**
+ * alsa mixer
+ */
+
+struct alsa_mixer;
+
+struct alsa_mixer *alsa_mixer_init(void);
+void alsa_mixer_finish(struct alsa_mixer *am);
+void alsa_mixer_configure(struct alsa_mixer *am, ConfigParam *param);
+bool alsa_mixer_open(struct alsa_mixer *am);
+bool alsa_mixer_control(struct alsa_mixer *am, int cmd, void *arg);
+void alsa_mixer_close(struct alsa_mixer *am);
+
+/**
+ * oss mixer
+ */
+
+struct oss_mixer;
+
+struct oss_mixer *oss_mixer_init(void);
+void oss_mixer_finish(struct oss_mixer *am);
+void oss_mixer_configure(struct oss_mixer *am, ConfigParam *param);
+bool oss_mixer_open(struct oss_mixer *am);
+bool oss_mixer_control(struct oss_mixer *am, int cmd, void *arg);
+void oss_mixer_close(struct oss_mixer *am);
+
+#endif

src/mixer/alsa_mixer.c

+
+#include "../output_api.h"
+#include "../mixer.h"
+
+#include <glib.h>
+#include <alsa/asoundlib.h>
+
+#define VOLUME_MIXER_ALSA_DEFAULT		"default"
+#define VOLUME_MIXER_ALSA_CONTROL_DEFAULT	"PCM"
+
+struct alsa_mixer {
+	char *device;
+	char *control;
+	snd_mixer_t *handle;
+	snd_mixer_elem_t *elem;
+	long volume_min;
+	long volume_max;
+	int volume_set;
+};
+
+struct alsa_mixer *
+alsa_mixer_init(void)
+{
+	struct alsa_mixer *am = g_malloc(sizeof(struct alsa_mixer));
+	am->device = NULL;
+	am->control = NULL;
+	am->handle = NULL;
+	am->elem = NULL;
+	am->volume_min = 0;
+	am->volume_max = 0;
+	am->volume_set = -1;
+	return am;
+}
+
+void
+alsa_mixer_finish(struct alsa_mixer *am)
+{
+	g_free(am);
+}
+
+void
+alsa_mixer_configure(struct alsa_mixer *am, ConfigParam *param)
+{
+	BlockParam *bp;
+
+	if ((bp = getBlockParam(param, "mix_device")))
+		am->device = bp->value;
+	if ((bp = getBlockParam(param, "mix_control")))
+		am->control = bp->value;
+}
+
+void
+alsa_mixer_close(struct alsa_mixer *am)
+{
+	if (am->handle) snd_mixer_close(am->handle);
+	am->handle = NULL;
+}
+
+bool
+alsa_mixer_open(struct alsa_mixer *am)
+{
+	int err;
+	snd_mixer_elem_t *elem;
+	const char *control_name = VOLUME_MIXER_ALSA_CONTROL_DEFAULT;
+	const char *device = VOLUME_MIXER_ALSA_DEFAULT;
+
+	if (am->device) {
+		device = am->device;
+	}
+	err = snd_mixer_open(&am->handle, 0);
+	snd_config_update_free_global();
+	if (err < 0) {
+		g_warning("problems opening alsa mixer: %s\n", snd_strerror(err));
+		return false;
+	}
+
+	if ((err = snd_mixer_attach(am->handle, device)) < 0) {
+		g_warning("problems attaching alsa mixer: %s\n",
+			snd_strerror(err));
+		alsa_mixer_close(am);
+		return false;
+	}
+
+	if ((err = snd_mixer_selem_register(am->handle, NULL,
+		    NULL)) < 0) {
+		g_warning("problems snd_mixer_selem_register'ing: %s\n",
+			snd_strerror(err));
+		alsa_mixer_close(am);
+		return false;
+	}
+
+	if ((err = snd_mixer_load(am->handle)) < 0) {
+		g_warning("problems snd_mixer_selem_register'ing: %s\n",
+			snd_strerror(err));
+		alsa_mixer_close(am);
+		return false;
+	}
+
+	elem = snd_mixer_first_elem(am->handle);
+
+	if (am->control) {
+		control_name = am->control;
+	}
+
+	while (elem) {
+		if (snd_mixer_elem_get_type(elem) == SND_MIXER_ELEM_SIMPLE) {
+			if (strcasecmp(control_name,
+				       snd_mixer_selem_get_name(elem)) == 0) {
+				break;
+			}
+		}
+		elem = snd_mixer_elem_next(elem);
+	}
+
+	if (elem) {
+		am->elem = elem;
+		snd_mixer_selem_get_playback_volume_range(am->elem,
+							  &am->volume_min,
+							  &am->volume_max);
+		return true;
+	}
+
+	g_warning("can't find alsa mixer control \"%s\"\n", control_name);
+
+	alsa_mixer_close(am);
+	return false;
+}
+
+bool
+alsa_mixer_control(struct alsa_mixer *am, int cmd, void *arg)
+{
+	switch (cmd) {
+	case AC_MIXER_CONFIGURE:
+		alsa_mixer_configure(am, (ConfigParam *)arg);
+		if (am->handle)
+			alsa_mixer_close(am);
+		return true;
+	case AC_MIXER_GETVOL:
+	{
+		int err;
+		int ret, *volume = arg;
+		long level;
+
+		if (!am->handle && !alsa_mixer_open(am)) {
+			return false;
+		}
+		if ((err = snd_mixer_handle_events(am->handle)) < 0) {
+			g_warning("problems getting alsa volume: %s (snd_mixer_%s)\n",
+				snd_strerror(err), "handle_events");
+			alsa_mixer_close(am);
+			return false;
+		}
+		if ((err = snd_mixer_selem_get_playback_volume(am->elem,
+			       SND_MIXER_SCHN_FRONT_LEFT, &level)) < 0) {
+			g_warning("problems getting alsa volume: %s (snd_mixer_%s)\n",
+				snd_strerror(err), "selem_get_playback_volume");
+			alsa_mixer_close(am);
+			return false;
+		}
+		ret = ((am->volume_set / 100.0) * (am->volume_max - am->volume_min)
+			+ am->volume_min) + 0.5;
+		if (am->volume_set > 0 && ret == level) {
+			ret = am->volume_set;
+		} else {
+			ret = (int)(100 * (((float)(level - am->volume_min)) /
+				(am->volume_max - am->volume_min)) + 0.5);
+		}
+		*volume = ret;
+		return true;
+	}
+	case AC_MIXER_SETVOL:
+	{
+		float vol;
+		long level;
+		int *volume = arg;
+		int err;
+
+		if (!am->handle && !alsa_mixer_open(am)) {
+			return false;
+		}
+		vol = *volume;
+
+		am->volume_set = vol + 0.5;
+		am->volume_set = am->volume_set > 100 ? 100 :
+			    (am->volume_set < 0 ? 0 : am->volume_set);
+
+		level = (long)(((vol / 100.0) * (am->volume_max - am->volume_min) +
+			 am->volume_min) + 0.5);
+		level = level > am->volume_max ? am->volume_max : level;
+		level = level < am->volume_min ? am->volume_min : level;
+
+		if ((err = snd_mixer_selem_set_playback_volume_all(am->elem,
+								level)) < 0) {
+			g_warning("problems setting alsa volume: %s\n",
+				snd_strerror(err));
+			alsa_mixer_close(am);
+			return false;
+		}
+		return true;
+	}
+	default:
+		g_warning("Unsuported alsa control\n");
+		break;
+	}
+	return false;
+}

src/mixer/oss_mixer.c

+
+#include <glib.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "../output_api.h"
+#include "../mixer.h"
+
+#if defined(__OpenBSD__) || defined(__NetBSD__)
+# include <soundcard.h>
+#else /* !(defined(__OpenBSD__) || defined(__NetBSD__) */
+# include <sys/soundcard.h>
+#endif /* !(defined(__OpenBSD__) || defined(__NetBSD__) */
+
+#define VOLUME_MIXER_OSS_DEFAULT		"/dev/mixer"
+
+struct oss_mixer {
+	const char *device;
+	const char *control;
+	int device_fd;
+	int volume_control;
+};
+
+struct oss_mixer *oss_mixer_init(void);
+void oss_mixer_finish(struct oss_mixer *am);
+void oss_mixer_configure(struct oss_mixer *am, ConfigParam *param);
+bool oss_mixer_open(struct oss_mixer *am);
+bool oss_mixer_control(struct oss_mixer *am, int cmd, void *arg);
+void oss_mixer_close(struct oss_mixer *am);
+
+struct oss_mixer *
+oss_mixer_init(void)
+{
+	struct oss_mixer *om = g_malloc(sizeof(struct oss_mixer));
+	om->device = NULL;
+	om->control = NULL;
+	om->device_fd = -1;
+	om->volume_control = SOUND_MIXER_PCM;
+	return om;
+}
+
+void
+oss_mixer_finish(struct oss_mixer *om)
+{
+	g_free(om);
+}
+
+void
+oss_mixer_configure(struct oss_mixer *om, ConfigParam *param)
+{
+	BlockParam *bp;
+	bp = getBlockParam(param, "mix_device");
+	if (bp) {
+		om->device = bp->value;
+	}
+	bp = getBlockParam(param, "mix_control");
+	if (bp) {
+		om->control = bp->value;
+	}
+}
+
+void
+oss_mixer_close(struct oss_mixer *om)
+{
+	if (om->device_fd != -1)
+		while (close(om->device_fd) && errno == EINTR) ;
+	om->device_fd = -1;
+}
+
+static int
+oss_find_mixer(const char *name)
+{
+	const char *labels[SOUND_MIXER_NRDEVICES] = SOUND_DEVICE_LABELS;
+	size_t name_length = strlen(name);
+
+	for (unsigned i = 0; i < SOUND_MIXER_NRDEVICES; i++) {
+		if (strncasecmp(name, labels[i], name_length) == 0 &&
+		    (labels[i][name_length] == 0 ||
+		     labels[i][name_length] == ' '))
+			return i;
+	}
+	return -1;
+}
+
+bool
+oss_mixer_open(struct oss_mixer *om)
+{
+	const char *device = VOLUME_MIXER_OSS_DEFAULT;
+
+	if (om->device) {
+		device = om->device;
+	}
+
+	if ((om->device_fd = open(device, O_RDONLY)) < 0) {
+		g_warning("Unable to open oss mixer \"%s\"\n", device);
+		return false;
+	}
+
+	if (om->control) {
+		int i;
+		int devmask = 0;
+
+		if (ioctl(om->device_fd, SOUND_MIXER_READ_DEVMASK, &devmask) < 0) {
+			g_warning("errors getting read_devmask for oss mixer\n");
+			oss_mixer_close(om);
+			return false;
+		}
+		i = oss_find_mixer(om->control);
+
+		if (i < 0) {
+			g_warning("mixer control \"%s\" not found\n",
+				om->control);
+			oss_mixer_close(om);
+			return false;
+		} else if (!((1 << i) & devmask)) {
+			g_warning("mixer control \"%s\" not usable\n",
+				om->control);
+			oss_mixer_close(om);
+			return false;
+		}
+		om->volume_control = i;
+	}
+	return true;
+}
+
+bool
+oss_mixer_control(struct oss_mixer *om, int cmd, void *arg)
+{
+	switch (cmd) {
+	case AC_MIXER_CONFIGURE:
+		oss_mixer_configure(om, (ConfigParam *)arg);
+		//if (om->device_fd >= 0)
+			oss_mixer_close(om);
+		return true;
+		break;
+	case AC_MIXER_GETVOL:
+	{
+		int left, right, level;
+		int *ret;
+
+		if (om->device_fd < 0 && !oss_mixer_open(om)) {
+			return false;
+		}
+
+		if (ioctl(om->device_fd, MIXER_READ(om->volume_control), &level) < 0) {
+			oss_mixer_close(om);
+			g_warning("unable to read oss volume\n");
+			return false;
+		}
+
+		left = level & 0xff;
+		right = (level & 0xff00) >> 8;
+
+		if (left != right) {
+			g_warning("volume for left and right is not the same, \"%i\" and "
+				"\"%i\"\n", left, right);
+		}
+		ret = (int *) arg;
+		*ret = left;
+		return true;
+	}
+	case AC_MIXER_SETVOL:
+	{
+		int new;
+		int level;
+		int *value = arg;
+
+		if (om->device_fd < 0 && !oss_mixer_open(om)) {
+			return false;
+		}
+
+		new = *value;
+		if (new < 0) {
+			new = 0;
+		} else if (new > 100) {
+			new = 100;
+		}
+
+		level = (new << 8) + new;
+
+		if (ioctl(om->device_fd, MIXER_WRITE(om->volume_control), &level) < 0) {
+			g_warning("unable to set oss volume\n");
+			oss_mixer_close(om);
+			return false;
+		}
+		return true;
+	}
+	default:
+		g_warning("Unsuported oss control\n");
+		break;
+	}
+	return false;
+}

src/output/alsa_plugin.c

@@ -18,6 +18,7 @@
 
 #include "../output_api.h"
 #include "../utils.h"
+#include "../mixer.h"
 
 #include <glib.h>
 #include <alsa/asoundlib.h>
@@ -51,6 +52,9 @@ typedef struct _AlsaData {
 	unsigned int period_time;
 	int sampleSize;
 	int useMmap;
+
+	struct alsa_mixer *mixer;
+
 } AlsaData;
 
 static const char *
@@ -71,12 +75,15 @@ static AlsaData *newAlsaData(void)
 	ret->buffer_time = MPD_ALSA_BUFFER_TIME_US;
 	ret->period_time = 0;
 
+	ret->mixer = alsa_mixer_init();
+
 	return ret;
 }
 
 static void freeAlsaData(AlsaData * ad)
 {
 	g_free(ad->device);
+	alsa_mixer_finish(ad->mixer);
 	free(ad);
 }
 
@@ -125,8 +132,10 @@ static void *alsa_initDriver(mpd_unused struct audio_output *ao,
 		free_global_registered = 1;
 	}
 
-	if (param)
+	if (param) {
 		alsa_configure(ad, param);
+		alsa_mixer_configure(ad->mixer, param);
+	}
 
 	return ad;
 }
@@ -181,6 +190,8 @@ static bool alsa_openDevice(void *data, struct audio_format *audioFormat)
 	unsigned int period_time, period_time_ro;
 	unsigned int buffer_time;
 
+	alsa_mixer_open(ad->mixer);
+
 	if ((bitformat = get_bitformat(audioFormat)) == SND_PCM_FORMAT_UNKNOWN)
 		g_warning("ALSA device \"%s\" doesn't support %u bit audio\n",
 			  alsa_device(ad), audioFormat->bits);
@@ -403,6 +414,7 @@ static void alsa_closeDevice(void *data)
 		snd_pcm_close(ad->pcmHandle);
 		ad->pcmHandle = NULL;
 	}
+	alsa_mixer_close(ad->mixer);
 }
 
 static bool
@@ -436,6 +448,13 @@ alsa_playAudio(void *data, const char *playChunk, size_t size)
 	return true;
 }
 
+static bool
+alsa_control(void *data, int cmd, void *arg)
+{
+	AlsaData *ad = data;
+	return alsa_mixer_control(ad->mixer, cmd, arg);
+}
+
 const struct audio_output_plugin alsaPlugin = {
 	.name = "alsa",
 	.test_default_device = alsa_testDefault,
@@ -445,4 +464,5 @@ const struct audio_output_plugin alsaPlugin = {
 	.play = alsa_playAudio,
 	.cancel = alsa_dropBufferedAudio,
 	.close = alsa_closeDevice,
+	.control = alsa_control
 };

src/output/oss_plugin.c

@@ -20,6 +20,7 @@
  */
 
 #include "../output_api.h"
+#include "../mixer.h"
 
 #include <glib.h>
 #include <sys/stat.h>
@@ -53,6 +54,7 @@ typedef struct _OssData {
 	int numSupported[3];
 	int *unsupported[3];
 	int numUnsupported[3];
+	struct oss_mixer *mixer;
 } OssData;
 
 enum oss_support {
@@ -273,6 +275,8 @@ static OssData *newOssData(void)
 	supportParam(ret, SNDCTL_DSP_CHANNELS, 2);
 	supportParam(ret, SNDCTL_DSP_SAMPLESIZE, 16);
 
+	ret->mixer = oss_mixer_init();
+
 	return ret;
 }
 
@@ -285,6 +289,8 @@ static void freeOssData(OssData * od)
 	g_free(od->unsupported[OSS_CHANNELS]);
 	g_free(od->unsupported[OSS_BITS]);
 
+	oss_mixer_finish(od->mixer);
+
 	free(od);
 }
 
@@ -348,6 +354,7 @@ static void *oss_open_default(ConfigParam *param)
 		if (ret[i] == 0) {
 			OssData *od = newOssData();
 			od->device = default_devices[i];
+			oss_mixer_configure(od->mixer, param);
 			return od;
 		}
 	}
@@ -388,6 +395,7 @@ static void *oss_initDriver(mpd_unused struct audio_output *audioOutput,
 		if (bp) {
 			OssData *od = newOssData();
 			od->device = bp->value;
+			oss_mixer_configure(od->mixer, param);
 			return od;
 		}
 	}
@@ -513,6 +521,8 @@ oss_openDevice(void *data, struct audio_format *audioFormat)
 		od->audio_format.bits, od->audio_format.channels,
 		od->audio_format.sample_rate);
 
+	oss_mixer_open(od->mixer);
+
 	return ret;
 }
 
@@ -521,6 +531,7 @@ static void oss_closeDevice(void *data)
 	OssData *od = data;
 
 	oss_close(od);
+	oss_mixer_close(od->mixer);
 }
 
 static void oss_dropBufferedAudio(void *data)
@@ -559,6 +570,13 @@ oss_playAudio(void *data, const char *playChunk, size_t size)
 	return true;
 }
 
+static bool
+oss_control(void *data, int cmd, void *arg)
+{
+	OssData *od = data;
+	return oss_mixer_control(od->mixer, cmd, arg);
+}
+
 const struct audio_output_plugin ossPlugin = {
 	.name = "oss",
 	.test_default_device = oss_testDefault,
@@ -568,4 +586,5 @@ const struct audio_output_plugin ossPlugin = {
 	.play = oss_playAudio,
 	.cancel = oss_dropBufferedAudio,
 	.close = oss_closeDevice,
+	.control = oss_control,
 };

src/output_api.h

@@ -101,6 +101,12 @@ struct audio_output_plugin {
 	void (*close)(void *data);
 
 	/**
+	 * Control the device. Usualy used for implementing
+	 * set and get mixer levels
+	 */
+	bool (*control)(void *data, int cmd, void *arg);
+
+	/**
 	 * Display metadata for the next chunk.  Optional method,
 	 * because not all devices can display metadata.
 	 */
@@ -118,6 +124,12 @@ enum audio_output_command {
 	AO_COMMAND_KILL
 };
 
+enum audio_control_command {
+	AC_MIXER_GETVOL = 0,
+	AC_MIXER_SETVOL,
+	AC_MIXER_CONFIGURE,
+};
+
 struct audio_output;
 
 const char *audio_output_get_name(const struct audio_output *ao);

src/volume.h

@@ -24,16 +24,15 @@
 #define VOLUME_MIXER_OSS	"oss"
 #define VOLUME_MIXER_ALSA	"alsa"
 #define VOLUME_MIXER_SOFTWARE	"software"
+#define VOLUME_MIXER_HARDWARE	"hardware"
 
-void initVolume(void);
+void volume_init(void);
 
-void openVolumeDevice(void);
+void volume_finish(void);
 
-void finishVolume(void);
+int volume_level_get(void);
 
-int getVolumeLevel(void);
-
-int changeVolumeLevel(int change, int rel);
+int volume_level_change(int change, int rel);
 
 void read_sw_volume_state(FILE *fp);