rtpenc_aac: Fix 10l bug

Fixes CID602564
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/rtpenc_aac.c

@@ -47,8 +47,8 @@ void ff_rtp_send_aac(AVFormatContext *s1, const uint8_t *buff, int size)
             memmove(p + 2, s->buf + 2, au_size);
         }
         /* Write the AU header size */
-        p[0] = ((au_size * 8) & 0xFF) >> 8;
-        p[1] = (au_size * 8) & 0xFF;
+        p[0] = au_size >> 5;
+        p[1] = (au_size & 0x1F) << 3;
 
         ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);