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Re: OGG container

From: Thierry MICHEL <tmichel@w3.org>
Date: Tue, 21 Sep 2010 15:22:12 +0200
Message-ID: <4C98B184.7030809@w3.org>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
CC: "public-media-annotation@w3.org" <public-media-annotation@w3.org>
Silvia,

I think you are misunderstanding/missing what we have decided during our 
last F2F in Sophia.

Your contribution is still included in the latest draft of the Ontology 
specification
http://dev.w3.org/2008/video/mediaann/mediaont-1.0/mediaont-1.0.html#d0e8203

Your OGG table is included in the following section
5.2.2 Multimedia metadata formats mapping tables

but we have created a new section for
5.2.3 Multimedia container formats mapping tables

where we have added these containers: 3gp, flv, mov, mp4, ogg, webm

Feel free to update the OGG container table, if you have expertize on 
this container,
the file is at:
http://dev.w3.org/2008/video/mediaann/mediaont-1.0/mappings/container-OGG.htm

Thierry.






Le 21/09/2010 14:55, Silvia Pfeiffer a écrit :
> I think you misunderstand some of the way in which Ogg works. Skeleton is
> actually part of the container format and thus all the metadata that
> skeleton supports has to be attributed to Ogg.  See:
> http://github.com/cpearce/OggIndex/blob/master/Skeleton-4.0-Index-Specification.txt
>
> May I ask what happened to the Ogg mapping table that I previously
> contributed and why that is not being used? I have contributed a mapping
> table for Ogg files, which I think is now at
> http://dev.w3.org/2008/video/mediaann/mediaont-1.0/mediaont-1.0.html#d0e8203.
> It includes the skeleton metadata, which should be counted as
> container-level metadata.
>
> Cheers,
> Silvia.
>
>
>
> On Tue, Sep 21, 2010 at 8:28 PM, Thierry MICHEL<tmichel@w3.org>  wrote:
>
>>
>> I have investigated into the OGG container to fill our OGG mapping table
>> [1]
>>
>> Ogg does not know anything about the content it carries and leaves it to
>> the media mapping of each codec to declare and describe itself. There is no
>> meta information available at the Ogg level about the content tracks
>> encapsulated within an Ogg physical bitstream.
>>
>> read more at
>> http://www.xiph.org/ogg/doc/skeleton.html
>>
>>
>>
>> Ogg does not replicate codec-specific metadata into the mux layer in an
>> attempt to make the mux and codec layer implementations 'fully separable'.
>> Things like specific timebase, keyframing strategy, frame duration, etc, do
>> not appear in the Ogg container. The mux layer is, instead, expected to
>> query a codec through a centralized interface, left to the implementation,
>> for this data when it is needed.
>>
>> Though modern design wisdom usually prefers to predict all possible needs
>> of current and future codecs then embed these dependencies and the required
>> metadata into the container itself, this strategy increases container
>> specification complexity, fragility, and rigidity.
>>
>> read more at
>> http://www.xiph.org/ogg/doc/oggstream.html
>>
>> Therfore I guess there is not much to fill in our OGG mapping table.
>>
>> Thierry
>>
>>
>> [1]
>> http://dev.w3.org/2008/video/mediaann/mediaont-1.0/mediaont-1.0.html#d0e12764
>>
>>
>
Received on Tuesday, 21 September 2010 13:22:41 GMT

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