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file: add (very) basic support for detecting mpeg4 formats

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This commit is contained in:
Alex Musolino 2019-11-01 12:05:11 +10:30
parent 06786f2a71
commit 7fbd3fd4fe
1 changed files with 20 additions and 0 deletions
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20
sys/src/cmd/file.c
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@ -152,6 +152,7 @@ int ismbox(void);
int islimbo(void);
int istga(void);
int ismp3(void);
int ismp4(void);
int ismung(void);
int isp9bit(void);
int isp9font(void);
@ -201,6 +202,7 @@ int (*call[])(void) =
isface, /* ascii face file */
istga,
ismp3,
ismp4,
/* last resorts */
ismung, /* entropy compressed/encrypted */
@ -1242,6 +1244,24 @@ ismp3(void)
return 0;
}
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;
}
/*
* low entropy means encrypted
*/