Index: libavformat/matroskadec.c
===================================================================
--- libavformat/matroskadec.c	(revision 21575)
+++ libavformat/matroskadec.c	(working copy)
@@ -1383,6 +1383,11 @@
             st->codec->codec_type = CODEC_TYPE_AUDIO;
             st->codec->sample_rate = track->audio.out_samplerate;
             st->codec->channels = track->audio.channels;
+
+            // parsing is needed for (E-)AC-3 to get all codec parameters
+            if (st->codec->codec_id == CODEC_ID_AC3 ||
+                st->codec->codec_id == CODEC_ID_EAC3)
+                st->need_parsing = AVSTREAM_PARSE_FULL;
         } else if (track->type == MATROSKA_TRACK_TYPE_SUBTITLE) {
             st->codec->codec_type = CODEC_TYPE_SUBTITLE;
         }