+int
+ismp4(void)
+{
+ if(nbuf <= 12)
+ return 0;
+ if(memcmp(&buf[4], "ftyp", 4) != 0)
+ return 0;
+ if(memcmp(&buf[8], "isom", 4) == 0){
+ print("%s\n", mime ? "video/mp4" : "mp4 video");
+ return 1;
+ }
+ if(memcmp(&buf[8], "M4A ", 4) == 0){
+ print("%s\n", mime ? "audio/m4a" : "m4a audio");
+ return 1;
+ }
+ return 0;
+}
+