avformat/utils: dont wait for a first dts on demuxers which have AVFMT_NOTIMESTAMPS set

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/utils.c

@@ -3204,6 +3204,7 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                 !st->codec->extradata)
                 break;
             if (st->first_dts == AV_NOPTS_VALUE &&
+                !(ic->iformat->flags & AVFMT_NOTIMESTAMPS) &&
                 (st->codec->codec_type == AVMEDIA_TYPE_VIDEO ||
                  st->codec->codec_type == AVMEDIA_TYPE_AUDIO))
                 break;