yop_probe: check more fields to avoid detecting random data as yop

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

libavformat/yop.c

@@ -38,10 +38,15 @@ typedef struct yop_dec_context {
 static int yop_probe(AVProbeData *probe_packet)
 {
     if (AV_RB16(probe_packet->buf) == AV_RB16("YO")  &&
+        probe_packet->buf[2]<10                      &&
+        probe_packet->buf[3]<10                      &&
         probe_packet->buf[6]                         &&
         probe_packet->buf[7]                         &&
         !(probe_packet->buf[8] & 1)                  &&
-        !(probe_packet->buf[10] & 1))
+        !(probe_packet->buf[10] & 1)                 &&
+        AV_RL16(probe_packet->buf + 12 + 6) >= 920    &&
+        AV_RL16(probe_packet->buf + 12 + 6) < probe_packet->buf[12] * 3 + 4 + probe_packet->buf[7] * 2048
+    )
         return AVPROBE_SCORE_MAX * 3 / 4;
 
     return 0;