avformat/avidec: optimize probe

about 2x as fast
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avidec.c

@@ -1863,8 +1863,8 @@ static int avi_probe(AVProbeData *p)
 
     /* check file header */
     for (i = 0; avi_headers[i][0]; i++)
-        if (!memcmp(p->buf,     avi_headers[i],     4) &&
-            !memcmp(p->buf + 8, avi_headers[i] + 4, 4))
+        if (AV_RL32(p->buf    ) == AV_RL32(avi_headers[i]    ) &&
+            AV_RL32(p->buf + 8) == AV_RL32(avi_headers[i] + 4))
             return AVPROBE_SCORE_MAX;
 
     return 0;