Suppress runaway index on streamed input

Originally committed as revision 11527 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mpeg.c

@@ -385,7 +385,8 @@ static int mpegps_read_pes_header(AVFormatContext *s,
     if(dts != AV_NOPTS_VALUE && ppos){
         int i;
         for(i=0; i<s->nb_streams; i++){
-            if(startcode == s->streams[i]->id) {
+            if(startcode == s->streams[i]->id &&
+               !url_is_streamed(s->pb) /* index useless on streams anyway */) {
                 ff_reduce_index(s, i);
                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
             }