@ -60,7 +60,8 @@ class SubSyncer:
self.reference_stream = "s:{}".format(i)
break
if not self.reference_stream:
using_what = "{0} embedded subtitle track".format(language_from_alpha3(embedded_subs['language'].alpha3))
using_what = "{0} embedded subtitle track".format(
language_from_alpha3(embedded_subs['language'].alpha3) or 'unknown language audio track')
self.reference_stream = "s:0"
elif 'audio' in data:
audio_tracks = data['audio']