[M4IF Technotes] iods & 3GPP

[Dave Singer]

At 11:42 +0200 9/4/02, AVARO Olivier FTRD/DIH/REN wrote:
>  > Hence, iods atom is not mandated in a 3GP file, and it shall
>>  be ignored in a file that addresses 3GP file compliance
>>  according to TS.26.234 Rel.4 and beyond.
>
>>  I also think that iods is not a part of ISO File format, but
>>  the MPEG-4 Specific file format which is inherited from ISO
>>  file format. 3GP file format is inherited from the ISO file
>>  format, which definitely makes the distinction between MPEG-4
>>  systems related elements, and the core file format template
>>  (i.e. ISO).
>
>I think there are some confusions there between an MPEG sub-group 
>(MPEG-4 Systems) and a specification (the ISO media File format). 
>File formats (the ISO File Format, MP4 File Format, AVC, ...) have 
>been developped by MPEG-4 Systems (later jointly with JPEG for the 
>ISO file format) so they *are* MPEG-4 Systems. What you mean I think 
>is that 3GPP decided not use the OD framework (another specification 
>developped by MPEG-4 Systems).
>
>All I am saying, is that people who care about having there content 
>used also on the internet (some company does ...) should better do 
>dual compatible files. What I am also saying is that this extra 
>burden is not ground on any technical reasons. There is NO technical 
>reason to derive yet another format from the ISO File format in the 
>3GPP case (while in some cases there are, e.g. we are currently 
>making such assessment for AVC coding that has some specifics). I am 
>saying this in the interest of interoperability and on the 
>minimization of the entropy in the multimedia standards. This is 
>also in the interest of future proofness.

Yes, as Olivier says, we have a lot of convergence here (which is 
good).  You may be able to play into a bigger market, and/or 
'future-proof' yourself by including a minimal OD/BIFS structure, as 
ISMA has done.  This is the reason that the 3G spec says that they 
are unused and should be ignored, and it does not say that you can't 
include them;  be as compatible as you wish with as many specs as you 
wish.
The 'ftyp' atom (sorry, box) at the front of the file labels which 
specs a file complies with.  Use it, and try to be as compatible as 
possible.  It's good for everyone to maximize interop.
-- 
David Singer
Apple Computer/QuickTime