rtpdec: Parse the next packet in the sequence if it is available, if the previous packet didn't return any data

Originally committed as revision 25460 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtpdec.c

@@ -694,6 +694,8 @@ int rtp_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
 {
     int rv = rtp_parse_one_packet(s, pkt, bufptr, len);
     s->prev_ret = rv;
+    while (rv == AVERROR(EAGAIN) && has_next_packet(s))
+        rv = rtp_parse_queued_packet(s, pkt);
     return rv ? rv : has_next_packet(s);
 }