ignore invalid packet_obj_size

fixes video5.asf

Originally committed as revision 9807 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/asf.c

@@ -773,6 +773,15 @@ static int asf_read_packet(AVFormatContext *s, AVPacket *pkt)
             asf->packet_multi_size -= asf->packet_obj_size;
             //printf("COMPRESS size  %d  %d  %d   ms:%d\n", asf->packet_obj_size, asf->packet_frag_timestamp, asf->packet_size_left, asf->packet_multi_size);
         }
+        if(   /*asf->packet_frag_size == asf->packet_obj_size*/
+              asf_st->frag_offset + asf->packet_frag_size <= asf_st->pkt.size
+           && asf_st->frag_offset + asf->packet_frag_size > asf->packet_obj_size){
+            av_log(s, AV_LOG_INFO, "ignoring invalid packet_obj_size (%d %d %d %d)\n",
+                asf_st->frag_offset, asf->packet_frag_size,
+                asf->packet_obj_size, asf_st->pkt.size);
+            asf->packet_obj_size= asf_st->pkt.size;
+        }
+
         if (   asf_st->pkt.size != asf->packet_obj_size
             || asf_st->frag_offset + asf->packet_frag_size > asf_st->pkt.size) { //FIXME is this condition sufficient?
             if(asf_st->pkt.data){