[ID3 Dev] ID3v2.5

Michal Vician id3v2 at audiott.com
Tue Feb 28 06:58:55 PST 2006


Thank you for explaining. Now I agree that padding is essential too.

----------------------------- Original message ---------------------------
Predmet: Re: [ID3 Dev] ID3v2.5
Od:      "Tom Sorensen" <tsorensen at gmail.com>
Dátum:   Tue, Február 28, 2006 3:41 pm
Komu:    id3v2 at id3.org
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There's that, there's issues of finding the tag (if a tag is variable
length, then it's a lot easier to find it at the start than somewhere in
the tail; not that it's a huge issue anyway). Note that you cannot put it
after the ID3v1 tag -- that violates the ID3v1 standard (which states that
the tag is the last 128 bytes). It must occur before that tag.

And while I didn't mention this, realize that dropping synchsafe
integers will cause issues. Any older hardware that isn't aware of ID3v2
tags may treat the tag as audio data, creating static for the end user.
There's a *lot* of devices out there (particularly in-dash CD/MP3 players
and portable CD/MP3 players) that this is applicable to. Worst case, it
could crash the device since the data is very much not audio data.

Newer devices at least recognize ID3v2 tags at the start of the file and
skip the entire tag body. They're unlikely to skip most end tags other
than ID3v1 (such as APEv2, ID3v2.4 footer, etc) though -- again, unless
they are coded to recognize them. Most aren't.

Tom

On 2/28/06, Jonathan del Strother <maillist at steelskies.com> wrote:
>
> On 28 Feb 2006, at 14:24, Michal Vician wrote:
>
> >> I disagree completely. If this was true, there wouldn't be nearly as
many tag editors, metadata services (with multiple versions of albums
in them), and so forth. Tag editing is certainly frequent enough to
be
> >> a concern. ***Padding is essential***.
> >
> > Well, wouldn't it be better to save id3v2 tag to the end to the file
(rigth after the ID3v1)? I'm pretty new to this mailing list (only
half a
> > year) and I really can't imagine why is ID3v2 tag stored at the very
beginning of file. Can anybody explain, please?
>
>
> I believe this is purely a benefit for streaming mp3s, where you don't
necessarily have the end of the file by the time you start playing.


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