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Subject: RE: Not reading genres
From: Fred Maxwell (rockbox_at_anti-spam.org)
Date: 2004-03-25


Jean Boullier wrote:

> Second comment, I am using MusicMatch "for ages" now (I bought a
> life-license long before Archos' birth) and I have never had any problem
> with the core tags, whatever mp3 tool I have used with my files. If they
> could read ID3v2 they could show the genre correctly, otherwise they
> found the ID3v1 at the end and show what MusicMatch had put there.

If you are using MusicMatch to rip CDs, then I strongly recommend that
switch to Exact Audio Copy (EAC). MusicMatch rips "blindly" and will not
detect CD reading errors and perform re-reads when errors occur. EAC will.
Also, EAC seems to create tags fine. It is freeware and you can download it
at http://exactaudiocopy.de/.

Is there information in ID3v2.x tags which is not present in ID3v1.1 tags
that you absolutely need? If not, I recommend going with ID3v1.1 tags.
They are compatible with everything whereas the v2.x tags are fraught with
problems.

As Linus says, the specs are confusing and subject to interpretation.
Sometimes MP3 files start with an ID3v2.x tag rather than an MP3 frame
header. ID3v2 tags are of variable size and the MP3 header is not
guaranteed to start immediately after the v2.x tag. Some tools apparently
add extra null bytes between the header and the first MP3 frame. An MP3
frame header starts with 11 sync bits (11111111b 111?????b) and the rest of
the header information follows. Needless to say, many files will contain
things that look like a frame header. Although the ID3v2 spec includes a
description of "syncsafe integers" and "unsynchronization bytes" which are
designed to ensure that ID3v2 tags do not look like a frame header, their
use is optional in most places. So there are many ID3v2 tags with byte
sequences that look like frame headers.

ID3v2.x tags are a mess and should be avoided. Hopefully, there will be an
unambiguous ID3v3 spec which specifically excludes the use of ID3v2.x tags
in any MP3 file containing an ID3v3 tag.

Regards,
  Fred Maxwell

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