Some types of MP3 are not matched about filetype HOT 5 OPEN

Seeing how it's done in the matcher functions with matching against only the 2 bytes, I've changed mine to this:

Mp3(buf []byte) bool {
return len(buf) > 2 &&
((buf[0] == 0x49 && buf[1] == 0x44 && buf[2] == 0x33) ||
(buf[0] == 0xFF && buf[1] == 0xfa) ||
(buf[0] == 0xFF && buf[1] == 0xfb))
}

The line with 0xfa is added with no other changes. That now works for me on the files that were previously failing.

Thanks!

from filetype.

Thanks for reporting this. What you mention makes absolute sense. The prefered way is using or logical operator.

from filetype.

There may be more possibilities for that second byte. See spec here: http://www.mpgedit.org/mpgedit/mpeg_format/mpeghdr.htm

Edit: I've been looking into this further. We only want MPEG-1 Layer III for MP3 audio, which leaves 0xFA and 0xFB depending on whether the 'protection' bit is set, so this is sufficient. Layer II would be MP2 files so another test.

from filetype.

I modified my local matcher function in this way to check the first bit only once:

func Mp3(buf []byte) bool {
return len(buf) > 2 &&
((buf[0] == 0x49 && buf[1] == 0x44 && buf[2] == 0x33) || // ID3v2
// Final bit (has crc32) may be or may not be set.
(buf[0] == 0xFF && (buf[1] == 0xFA || buf[1] == 0xFB)))
}

Would that be preferable?

from filetype.

I would suggest the same. One check is perfect.

from filetype.