avformat/thp: check fps value during probing

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

libavformat/thp.c

@@ -47,11 +47,16 @@ typedef struct ThpDemuxContext {
 
 static int thp_probe(AVProbeData *p)
 {
+    double d;
     /* check file header */
-    if (AV_RL32(p->buf) == MKTAG('T', 'H', 'P', '\0'))
-        return AVPROBE_SCORE_MAX;
-    else
+    if (AV_RL32(p->buf) != MKTAG('T', 'H', 'P', '\0'))
         return 0;
+
+    d = av_int2float(AV_RB32(p->buf + 16));
+    if (d < 0.1 || d > 1000 || isnan(d))
+        return AVPROBE_SCORE_MAX/4;
+
+    return AVPROBE_SCORE_MAX;
 }
 
 static int thp_read_header(AVFormatContext *s)