avformat/mpegts: print packet size warning only if new size differs from old

No case is known to have triggered this, but its more correct to check that the
new size differs.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mpegts.c

@@ -1929,7 +1929,7 @@ static void reanalyze(MpegTSContext *ts) {
         } else if (ts->size_stat[2] > SIZE_STAT_THRESHOLD) {
             newsize = TS_FEC_PACKET_SIZE;
         }
-        if (newsize) {
+        if (newsize && newsize != ts->raw_packet_size) {
             av_log(ts->stream, AV_LOG_WARNING, "changing packet size to %d\n", newsize);
             ts->raw_packet_size = newsize;
         }