ID3V2.4, unsynchronized frames and APIC frame

theirix theirix at
Mon Feb 4 16:16:22 CET 2008

Michael Pujos-2 wrote:
> would solve the problem. But it didn't. The spec is not super clear, so I
> tought maybe the frame data 
> (composed 99% by the image data) would be encoded as synchsafe integers?
> Can some spec guru confirm this ?
> What should I do to decode these frames ?
> A lot of Windows software seem to be writing that kind of frame, is it
> planned to add support in TagLib ?

Unfortunalety, a few of software properly support id3v2 unsynchronisation.

But there is another serious problem.
Taglib can correctly read unsynchronised data. It can't create unsynch tags.
But problem can appears when user read data from unsynchronised frame and
then try to modify data and write back. Taglib silently writes frame data
without needed unsynchronisation. In result we have damaged tag.
I think taglib should strictly allow or deny rendering unsynchronised tags
because in other way software that don't know about implementation (for
example, kid3) can damage your tags.

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