[ID3 Dev] Tag location

[Michal Vician]

Thanks for quick reply.

 > So far I haven't encountered any software that writes appended 
ID3v2.4 tags.
That's why I'm asking. Because I want to create one. I have already 
written one library which I use in my application "AudioTT". I found 
this library quite easy to modify and have some free time now. Therefore 
I decided to modify it, so it will be able to read and write all 
versions of ID3v2 and also make conversions between the versions.

> However, in the parsing software I've written, when searching for appended
> tags, I look for the 2.4 tag both before and after APEv2 tag.
Sure. In the spec there is written that you should do it like that.

     1. Look for a prepended tag using the pattern found in section 3.1.
     2. If a SEEK frame was found, use its values to guide further 
searching.
     3. Look for a tag footer, scanning from the back of the file.

> And I would still like to see it clarified in the spec that 2.4 tags at the
> beginning of a file cannot have a footer.  I think the current wording is
> ambiguous.  (To me it means that a prepended tag can have either a footer or
> padding but not both.)

Wow. What? I understand it exactly like that ("tag can have either a 
footer or padding but not both"). My implementation currently allows to 
write a footer in prepended tag.
So, your are saying that prepended tag MUST NOT have footer?? If yes, I 
would logically expect to have in specification something like this:
1. "Footer is intended for tag (or part of the tag) located at the end 
of the file. Prepended tag MUST NOT have footer, because footer brings 
no benefit to prepended tag."
2. "Padding is intended only for prepended tag. Appended tag MUST NOT 
have padding, because it would be useful, while there are no audio data 
under the tag."


Jim wrote:
> That's the way I've understood it as well.
>
> audio data
> -----------
> ID3v2.4
> -----------
> APEv2
> -----------
> Lyrics3v2
> -----------
> ID3v1
>
> So far I haven't encountered any software that writes appended ID3v2.4 tags.
> However, in the parsing software I've written, when searching for appended
> tags, I look for the 2.4 tag both before and after APEv2 tag.  (Just because
> I expect some confusion in early implementations of this.)
>
> And I would still like to see it clarified in the spec that 2.4 tags at the
> beginning of a file cannot have a footer.  I think the current wording is
> ambiguous.  (To me it means that a prepended tag can have either a footer or
> padding but not both.)
> ----- Original Message ----- 
> From: "Jud White" <jwhite at cdtag.com>
> To: <id3v2 at id3.org>
> Sent: Friday, January 12, 2007 11:36 AM
> Subject: Re: [ID3 Dev] Tag location
>
>
> Michal,
> That's my understanding (don't forget APE tags).  I think the idea is that
> anything aware of ID3v2 tags at the end of the file should be able to handle
> its position among other tags, whereas something that only reads ID3v1
> (+Lyrics3, or +APE) at the end of the file should not be disrupted.
>
> Jud

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