[ID3 Dev] Moving forward on Chapter Frames

Chris Newell chris.newell at rd.bbc.co.uk
Mon Nov 28 10:06:00 PST 2005

At 15:46 26/11/2005, you wrote:
>> Any MP3 reader/library that doesn't handle unknown tags is poorly
>> implemented *****and breaks the standard***** (at least v2.3 and v2.4 -- I
>> haven't read prior standards).
>What? Breaks the standard? I don't agree with you. There is nothing stated
>in ID3v2 specification that tag may contain other frames. There is only
>allowance in custom frames (X,Y,Z), but nothing stated that my application
>should handle frames like "HAHA" or "TOOT".


I'm not sure I agree. This is what it says in ID3 version 2.3.0:

   "Identifiers beginning with "X", "Y" and "Z" are for experimental use
   and free for everyone to use, without the need to set the
   experimental bit in the tag header. Have in mind that someone else
   might have used the same identifier as you. All other identifiers are
   either used or reserved for future use."

Where it says that all other identifiers are "reserved for future use" it must mean they are reserved within the context of ID3 version 2.3. This means that you might expect to find them in a future revision to version 2.3.

In my experience I've found the following version 2.4 frames types inside version 2.3 tags e.g:

And I've found some frames that aren't defined in any ID3v2 specification:

If this is typical of what ID3 parsers will accept then it may be acceptable to allow Chapter frames in ID3 v2.3 and v2.4.


Dr J.C. Newell
Digital Media Group, BBC Research & Development
Kingswood Warren, Woodland Way, Tadworth, Surrey 
KT20 6NP  UK
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