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Re: OGG container

From: Thierry MICHEL <tmichel@w3.org>
Date: Tue, 21 Sep 2010 16:22:50 +0200
Message-ID: <4C98BFBA.1040708@w3.org>
To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
CC: "public-media-annotation@w3.org" <public-media-annotation@w3.org>
http://www.w3.org/2008/WebVideo/Annotations/drafts/ontology10/CR/test.php?table=containerOGG

Le 21/09/2010 16:00, Silvia Pfeiffer a écrit :
> Hi Thierry,
>
> I saw the two sections and my reply was indeed targeted at the container
> format section. As I said: skeleton should be regarded as part of the
> container format and because Skeleton includes metadata, it should be
> counted (see
> http://github.com/cpearce/OggIndex/blob/master/Skeleton-4.0-Index-Specification.txt).
> My point was that all of the information you are after is already included
> in the previous table everywhere where it says "skeleton".


I guess in this previous metadata table, all these information which are 
now redondant with the OGG container table, should be removed.

OGG container table:
http://www.w3.org/2008/WebVideo/Annotations/drafts/ontology10/CR/test.php?table=containerOGG

thierry.

















>
> Anyway, happy to help - here is the table:
>
> <table class="ta20" border="1">
>
>    <tbody>
>      <tr class="ro-header">
>        <th class="col-mawg">MAWG</th>
>
>        <th class="col-relation">Relation</th>
>        <th class="col-attribute">OGG</th>
>
>        <th class="col-how">How to do the mapping</th>
>
>
>        <th class="col-datatype">Datatype</th>
>        <th class="col-xpath">XPath</th>
>
>      </tr>
>      <tr class="ro-header">
>        <td class="ma" colspan="6">Descriptive Properties (Core Set)</td>
>
>      </tr>
>      <tr class="ro-header">
>
>
>        <td class="col-mawg" colspan="6"><em>Identification</em></td>
>
>      </tr>
>      <tr class="ro-even">
>        <td class="ma">ma:identifier</td>
>
>        <td>exact</td>
>        <td>Name</td>
>        <td>Name field in skeleton header (new)</td>
>
>        <td>String</td>
>
>        <td>N/A</td>
>      </tr>
>
>      <tr class="ro-header">
>        <td class="col-mawg" colspan="6"><em>Content description</em></td>
>
>      </tr>
>      <tr class="ro-even">
>        <td class="ma">ma:description</td>
>
>        <td>related</td>
>
>        <td>Title</td>
>        <td>Title field in skeleton header (new)</td>
>
>        <td>String</td>
>        <td>N/A</td>
>      </tr>
>
>      <tr class="ro-header">
>        <td class="col-mawg" colspan="6"><em>Technical Properties</em></td>
>
>      </tr>
>
>      <tr class="ro-even">
>        <td class="ma">ma:frameSize</td>
>
>        <td>N/A at container level</td>
>        <td></td>
>        <td></td>
>
>        <td></td>
>        <td></td>
>      </tr>
>
>      <tr class="ro-odd">
>        <td class="ma">ma:compression</td>
>
>        <td>exact</td>
>        <td>Content-type</td>
>        <td>Content-type field of Skeleton header</td>
>
>        <td>MIME type</td>
>        <td>N/A</td>
>      </tr>
>
>      <tr class="ro-even">
>        <td class="ma">ma:duration</td>
>
>        <td>exact</td>
>        <td></td>
>        <td>calculate as duration = last_sample_time -
>
>          first_sample_time of OggIndex header of skeleton</td>
>        <td>Float (or rather: rational - rational)</td>
>
>        <td>N/A</td>
>      </tr>
>
>      <tr class="ro-odd">
>
>        <td class="ma">ma:format</td>
>        <td>exact</td>
>
>        <td>Content-type</td>
>        <td>Content-type field of Skeleton header</td>
>
>        <td>MIME type</td>
>        <td>N/A</td>
>      </tr>
>
>      <tr class="ro-even">
>        <td class="ma">ma:samplingRate</td>
>
>        <td>exact</td>
>        <td></td>
>        <td>calculate as granulerate = granulerate_numerator /
>
>          granulerate_denominator of Skeleton header</td>
>        <td>Rational (or rather int / int)</td>
>        <td>N/A</td>
>
>      </tr>
>
>      <tr class="ro-odd">
>        <td class="ma">ma:frameRate</td>
>
>        <td>exact</td>
>        <td></td>
>        <td>calculate as granulerate = granulerate_numerator /
>
>          granulerate_denominator of Skeleton header</td>
>        <td>Rational (or rather int / int)</td>
>        <td>N/A</td>
>
>      </tr>
>
>      <tr class="ro-even">
>        <td class="ma">ma:averageBitRate</td>
>
>        <td>exact</td>
>        <td></td>
>        <td>calculate as bitrate = length_of_segment / duration from
>
>          OggIndex headers of skeleton</td>
>        <td>Float</td>
>        <td>N/A</td>
>
>      </tr>
>
>      <tr class="ro-odd">
>        <td class="ma">ma:numTracks</td>
>
>        <td>N/A on container level</td>
>        <td></td>
>        <td></td>
>
>        <td></td>
>        <td></td>
>      </tr>
>
>    </tbody>
> </table>
>
> Cheers,
> Silvia.
>
>
> On Tue, Sep 21, 2010 at 11:22 PM, Thierry MICHEL<tmichel@w3.org>  wrote:
>
>> 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 14:23:18 GMT

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