[outputs/conf] New multiple 'alsa' sections split from 'audio'

README_ALSA.md

@@ -274,3 +274,29 @@ audio {
     mixer_device="hw:1"
 }
 ```
+
+## Multiple devices
+
+If your machine has multiple physical devices like our Raspberry Pi example above (the DAC hat and the onboard headphone jack), we can make all these devices available to `forked-daapd` using seperate `alsa { .. }` sections.
+
+NB: When introducing `alsa { .. }` section(s) the ALSA specific configuration in the `audio { .. }` section will be ignored.
+
+For example:
+```
+audio {
+    type = "alsa"
+}
+
+alsa "dac" {
+    card="dac"
+    mixer="Analogue"
+    mixer_device="hw:1"
+}
+
+alsa "headphones" {
+    card = "hw:0,0"
+    mixer = "PCM"
+    mixer_device = "hw:0"
+}
+
+```

forked-daapd.conf.in

@@ -216,6 +216,8 @@ audio {
 	# socket.
 #	server = ""
 
+        # ALSA settings can be definied in their own 'alsa { }' sections for 
+        # multiple devices
 	# Audio PCM device name for local audio output - ALSA only
 #	card = "default"
 
@@ -246,6 +248,25 @@ audio {
 #	adjust_period_seconds = 100
 }
 
+# ALSA device settings
+# Multiple sections can be defined for multiple ALSA devices on a host (i.e. a
+# RPi with onboard headphones and DAC hat).  ALSA may see these devices as hw:0
+# and hw:1 via 'aplay -l' (see README_ALSA)
+#
+# Overrides ALSA settings in 'audio' section
+#alsa "alsa default" {
+	# Audio PCM device name for local audio output
+#	card = "default"
+
+	# Mixer channel to use for volume control
+	# If not set, PCM will be used if available, otherwise Master.
+#	mixer = ""
+
+	# Mixer device to use for volume control
+	# If not set, the value for "card" will be used.
+#	mixer_device = ""
+#}
+
 # Pipe output
 # Allows forked-daapd to output audio data to a named pipe
 #fifo {

src/conffile.c

@@ -124,6 +124,17 @@ static cfg_opt_t sec_audio[] =
     CFG_END()
   };
 
+
+/* local ALSA audio section structure */
+static cfg_opt_t sec_alsa[] =
+  {
+    CFG_STR("card", "default", CFGF_NONE),
+    CFG_STR("mixer", NULL, CFGF_NONE),
+    CFG_STR("mixer_device", NULL, CFGF_NONE),
+    CFG_INT("offset_ms", 0, CFGF_NONE),
+    CFG_END()
+  };
+
 /* AirPlay/ApEx device section structure */
 static cfg_opt_t sec_airplay[] =
   {
@@ -201,6 +212,7 @@ static cfg_opt_t toplvl_cfg[] =
     CFG_SEC("general", sec_general, CFGF_NONE),
     CFG_SEC("library", sec_library, CFGF_NONE),
     CFG_SEC("audio", sec_audio, CFGF_NONE),
+    CFG_SEC("alsa", sec_alsa, CFGF_MULTI | CFGF_TITLE),
     CFG_SEC("airplay", sec_airplay, CFGF_MULTI | CFGF_TITLE),
     CFG_SEC("chromecast", sec_chromecast, CFGF_MULTI | CFGF_TITLE),
     CFG_SEC("fifo", sec_fifo, CFGF_NONE),

src/outputs/alsa.c

@@ -974,10 +974,12 @@ alsa_session_make(struct output_device *device, int callback_id)
 
   CHECK_NULL(L_LAUDIO, as = calloc(1, sizeof(struct alsa_session)));
 
+  DPRINTF(E_DBG, L_LAUDIO, "alsa dev=%s type=%s callback=%d\n", device->name, device->type_name, callback_id);
+
   as->device_id = device->id;
   as->callback_id = callback_id;
 
-  cfg_audio = cfg_getsec(cfg, "audio");
+  cfg_audio = cfg_size(cfg, "alsa") == 0 ? cfg_getsec(cfg, "audio") : cfg_gettsec(cfg, "alsa", device->name);
 
   as->devname = cfg_getstr(cfg_audio, "card");
   as->mixer_name = cfg_getstr(cfg_audio, "mixer");
@@ -1175,12 +1177,31 @@ alsa_write(struct output_buffer *obuf)
     }
 }
 
+static void
+alsa_device_add(cfg_t* cfg_audio, int id, const char* devname)
+{
+  struct output_device *device;
+  CHECK_NULL(L_LAUDIO, device = calloc(1, sizeof(struct output_device)));
+
+  device->id = id;
+  device->name = strdup(devname);
+  device->type = OUTPUT_TYPE_ALSA;
+  device->type_name = outputs_name(device->type);
+  device->has_video = 0;
+
+  DPRINTF(E_INFO, L_LAUDIO, "Adding ALSA device '%s' with name '%s'\n", cfg_getstr(cfg_audio, "card"), device->name);
+
+  player_device_add(device);
+}
+
 static int
 alsa_init(void)
 {
-  struct output_device *device;
   cfg_t *cfg_audio;
+  cfg_t *cfg_alsasec;
   const char *type;
+  int i;
+  int alsa_cfg_secn;
 
   // Is ALSA enabled in config?
   cfg_audio = cfg_getsec(cfg, "audio");
@@ -1191,17 +1212,19 @@ alsa_init(void)
   alsa_sync_disable = cfg_getbool(cfg_audio, "sync_disable");
   alsa_latency_history_size = cfg_getint(cfg_audio, "adjust_period_seconds");
 
-  CHECK_NULL(L_LAUDIO, device = calloc(1, sizeof(struct output_device)));
-
-  device->id = 0;
-  device->name = strdup(cfg_getstr(cfg_audio, "nickname"));
-  device->type = OUTPUT_TYPE_ALSA;
-  device->type_name = outputs_name(device->type);
-  device->has_video = 0;
-
-  DPRINTF(E_INFO, L_LAUDIO, "Adding ALSA device '%s' with name '%s'\n", cfg_getstr(cfg_audio, "card"), device->name);
-
-  player_device_add(device);
+  alsa_cfg_secn = cfg_size(cfg, "alsa");
+  if (alsa_cfg_secn == 0)
+    {
+      alsa_device_add(cfg_audio, 0, cfg_getstr(cfg_audio, "nickname"));
+    }
+  else
+    {
+      for (i = 0; i < alsa_cfg_secn; ++i)
+        {
+          cfg_alsasec = cfg_getnsec(cfg, "alsa", i);
+          alsa_device_add(cfg_alsasec, i, cfg_alsasec->title);
+        }
+    }
 
   snd_lib_error_set_handler(logger_alsa);