...

src/calibre/ebooks/metadata/book/base.py

@@ -730,8 +730,6 @@ class Metadata(object):
         if self.identifiers:
             fmt('Identifiers', u', '.join(['%s:%s'%(k, v) for k, v in
                 self.identifiers.iteritems()]))
-        if self.languages:
-            fmt('Languages', u', '.join(self.languages))
         if self.comments:
             fmt('Comments', self.comments)
 

src/calibre/ebooks/metadata/opf2.py

@@ -1328,7 +1328,8 @@ def metadata_to_opf(mi, as_string=True):
             '[http://calibre-ebook.com]'
 
     if not mi.languages:
-        mi.languages = ['UND']
+        lang = get_lang().replace('_', '-').partition('-')[0]
+        mi.languages = [lang]
 
     root = etree.fromstring(textwrap.dedent(
     '''
@@ -1380,7 +1381,7 @@ def metadata_to_opf(mi, as_string=True):
         factory(DC('rights'), mi.rights)
     for lang in mi.languages:
         if not lang or lang.lower() == 'und':
-            lang = get_lang().replace('_', '-').partition('-')[0]
+            continue
         factory(DC('language'), lang)
     if mi.tags:
         for tag in mi.tags:

src/calibre/ebooks/mobi/langcodes.py

@@ -4,6 +4,7 @@ __copyright__ = '2008, Kovid Goyal kovid@kovidgoyal.net'
 __docformat__ = 'restructuredtext en'
 
 from struct import pack
+from calibre.utils.localization import lang_as_iso639_1
 
 lang_codes = {
         }
@@ -314,7 +315,8 @@ def iana2mobi(icode):
         subtags = list(icode.split('-'))
         while len(subtags) > 0:
             lang = subtags.pop(0).lower()
-            if lang in IANA_MOBI:
+            lang = lang_as_iso639_1(lang)
+            if lang and lang in IANA_MOBI:
                 langdict = IANA_MOBI[lang]
                 break
 

src/calibre/ebooks/oeb/transforms/metadata.py

@@ -61,9 +61,11 @@ def meta_info_to_oeb_metadata(mi, m, log, override_input_metadata=False):
             m.add('identifier', val, scheme=typ.upper())
     if override_input_metadata and not set_isbn:
         m.filter('identifier', lambda x: x.scheme.lower() == 'isbn')
-    if not mi.is_null('language'):
+    if not mi.is_null('languages'):
         m.clear('language')
-        m.add('language', mi.language)
+        for lang in mi.languages:
+            if lang and lang.lower() not in ('und', ''):
+                m.add('language', lang)
     if not mi.is_null('series_index'):
         m.clear('series_index')
         m.add('series_index', mi.format_series_index())

src/calibre/utils/localization.py

@@ -260,6 +260,12 @@ def langnames_to_langcodes(names):
 
     return ans
 
+def lang_as_iso639_1(name_or_code):
+    code = canonicalize_lang(name_or_code)
+    if code is not None:
+        iso639 = _load_iso639()
+        return iso639['3to2'].get(code, None)
+
 _udc = None
 
 def get_udc():