libavformat: Only require first packet to be known for audio/video streams

It can take a long time before subtitles or data streams show up,
so we shouldn't wait for those before assuming we have all info
for streams.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/utils.c

@@ -2306,7 +2306,9 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                 break;
             if(st->parser && st->parser->parser->split && !st->codec->extradata)
                 break;
-            if(st->first_dts == AV_NOPTS_VALUE)
+            if (st->first_dts == AV_NOPTS_VALUE &&
+                (st->codec->codec_type == AVMEDIA_TYPE_VIDEO ||
+                 st->codec->codec_type == AVMEDIA_TYPE_AUDIO))
                 break;
         }
         if (i == ic->nb_streams) {