AW: [ID3 Dev] UTF16LE BOM FF FE incorrectly being identified as start of MP3 Audio

[Paul Taylor]

Ben Bennett wrote:
> I have to second Mathias.  I have never seen an incorrect tag size
> from any of the apps I have tested, or from any of the files I have
> found in the wild.  Note, the previous discussions have been of the
> bad _frame_ sizes.  But the overall tag size has always been correct.
>
> Anyway, I think scanning for MPEG frames is frought with peril since
> a MPEG data can be embedded within an ID3 tag (see the ID3 accessibility spec http://id3.org/id3v2-accessibility-1.0).
>   
This spec does mention the need for synchronisation quite a few times, 
so if written properly should not cause a problem, but i see that it could.
> I would trust the tag size if you hit an ID3v2 header, then scan for
> MPEG frames following that.
>
> 		    -ben
It seems a bit arbitary, my original method wont work because we may get 
false synchronisations in the ID3 tag, yet we can trust the ID3 header 
size because it is always calculated correctly. Well I guess you are 
ther authority on the subject , thanks for your advice  I think I will 
rework my code to read from the ID3 header upto the size reported, and 
then check that MP3Audio starts immediately afterwards for peace of 
mind. But IF the mp3 header does not start then we have a problem, Ill 
let you know if I have any files that fall into that category.

thanks Paul

 

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