Make dnxhd probe more strict, fail if we detect values in header that would

make our decoder fail anyway.
dnxhd probe now passes probetest.

Originally committed as revision 19847 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/raw.c

@@ -580,10 +580,19 @@ static int dirac_probe(AVProbeData *p)
 static int dnxhd_probe(AVProbeData *p)
 {
     static const uint8_t header[] = {0x00,0x00,0x02,0x80,0x01};
-    if (!memcmp(p->buf, header, 5))
-        return AVPROBE_SCORE_MAX;
-    else
+    int w, h, compression_id;
+    if (p->buf_size < 0x2c)
+        return 0;
+    if (memcmp(p->buf, header, 5))
+        return 0;
+    h = AV_RB16(p->buf + 0x18);
+    w = AV_RB16(p->buf + 0x1a);
+    if (!w || !h)
+        return 0;
+    compression_id = AV_RB32(p->buf + 0x28);
+    if (compression_id < 1237 || compression_id > 1253)
         return 0;
+    return AVPROBE_SCORE_MAX;
 }
 #endif