diff -Naur tvheadend.orig/src/api/api_service.c tvheadend/src/api/api_service.c
--- tvheadend.orig/src/api/api_service.c	2015-07-11 09:49:47.000000000 +0200
+++ tvheadend/src/api/api_service.c	2015-07-11 11:51:49.792280472 +0200
@@ -43,7 +43,8 @@
   get_u32(merge_same_name);
   get_u32(provider_tags);
   get_u32(network_tags);
-  
+  get_u32(language_tags);
+
   pthread_mutex_lock(&global_lock);
   service_mapper_start(&conf, uuids);
   pthread_mutex_unlock(&global_lock);
diff -Naur tvheadend.orig/src/service_mapper.c tvheadend/src/service_mapper.c
--- tvheadend.orig/src/service_mapper.c	2015-07-11 09:49:47.000000000 +0200
+++ tvheadend/src/service_mapper.c	2015-07-11 11:58:57.588932277 +0200
@@ -262,6 +262,14 @@
       channel_tag_map(channel_tag_find_by_name(si.si_network, 1), chn, chn);
     }
 
+    /* Language */
+    if (service_mapper_conf.language_tags) {
+      elementary_stream_t *st;
+      TAILQ_FOREACH(st, &s->s_components, es_link) {
+        channel_tag_map(channel_tag_find_by_name(st->es_lang, 1), chn, chn);
+      }
+    }
+
     /* save */
     idnode_notify_changed(&chn->ch_id);
     channel_save(chn);
diff -Naur tvheadend.orig/src/service_mapper.h tvheadend/src/service_mapper.h
--- tvheadend.orig/src/service_mapper.h	2015-07-11 09:49:47.000000000 +0200
+++ tvheadend/src/service_mapper.h	2015-07-11 11:52:26.404822752 +0200
@@ -28,6 +28,7 @@
   int merge_same_name;    ///< Merge entries with the same name
   int provider_tags;      ///< Create tags based on provider name
   int network_tags;       ///< Create tags based on network name (useful for multi adapter equipments)
+  int language_tags;      ///< Create tags based on language (feature request #2504)
 } service_mapper_conf_t;
 
 typedef struct service_mapper_status
diff -Naur tvheadend.orig/src/version.c tvheadend/src/version.c
--- tvheadend.orig/src/version.c	1970-01-01 01:00:00.000000000 +0100
+++ tvheadend/src/version.c	2015-07-11 11:53:01.599382759 +0200
@@ -0,0 +1 @@
+const char *tvheadend_version = "4.1-356~gd9de91c-dirty";
diff -Naur tvheadend.orig/src/webui/static/app/servicemapper.js tvheadend/src/webui/static/app/servicemapper.js
--- tvheadend.orig/src/webui/static/app/servicemapper.js	2015-07-11 13:37:23.675156368 +0200
+++ tvheadend/src/webui/static/app/servicemapper.js	2015-07-11 13:30:36.515246568 +0200
@@ -110,9 +110,14 @@
         fieldLabel: _('Create network tags'),
         checked: false
     });
+    var langtagCheck = new Ext.form.Checkbox({
+        name: 'language_tags',
+        fieldLabel: _('Create ISO-639 language tags'),
+        checked: false
+    });
 
     // TODO: provider list
-    items = [availCheck, ftaCheck, mergeCheck, provtagCheck, nettagCheck];
+    items = [availCheck, ftaCheck, mergeCheck, provtagCheck, nettagCheck, langtagCheck];
 
     /* Form */
     var undoBtn = new Ext.Button({