No subject

as you have references to the ES contained in this file, as Dave detailed.
But if you want to have a file whose information and references to tracks is 
self-contained, you must have an iods atom since this one is the first pointer 
to the other elements. For example, an audio/video file for local playback 
(without use of external reference) must have an IODS atom referring to a BIFS 
and OD track, the OD track referring to the audio and video tracks.
Some MPEG-4 players interpret this iods, bifs and OD information to support 
multiple MPEG-4 objects. In the case of 3GPP, this information is optional 
since the structure is pretty simple and does not require such information. You 
might want to add it in the file if you wish to be compatible with ISO but non-
3GPP players.
Boris
> At 10:18 -0600 9/3/02, Richard Shields wrote:
> >Giuliano,
> >
> >
> >
> >The 3GPP spec that I have states that "MPEG-4 system architectural 
> >elements (e.g. BIFS scene description tracks or OD Object 
> >descriptors) are optional and shall be ignored." (clause 9.2.4).
> 
> It's no longer mandatory in the ISO spec, by the way, as MP4 files 
> can be the target of an ES URL, or the target of a data-reference, 
> even in the mpeg-4 context.
> 
> But yes, these elements aren't used by or needed in the 3G spec.
> 
> >
> >
> >
> >-Richard
> >
> >
> >
> >-----Original Message-----
> >From: Catrambone Giuliano [mailto:Giuliano.Catrambone   h3g.it]
> >Sent: Tuesday, September 03, 2023 8:46 AM
> >To: technotes   lists.m4if.org
> >Subject: [M4IF Technotes] iods & 3GPP
> >
> >
> >
> >Hi,
> >
> >     I know that the iods atom is mandatory in ISO spec.
> >
> >     Do you know if the iods atom is mandatory in the 3GPP?
> >
> >
> >
> >         giuliano
> >
> >
> >
> >    
> 
> 
> -- 
> David Singer
> Apple Computer/QuickTime

Boris Felts
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