Re: Liaison Statement to W3C (SC 29 N 13268)

On Thu, Feb 21, 2013 at 7:55 PM, Jean-Claude Dufourd <
jean-claude.dufourd@telecom-paristech.fr> wrote:

>  Le 21/2/13 04:58 , Silvia Pfeiffer a écrit :
>
> On Thu, Feb 21, 2013 at 8:37 AM, Bob Lund <B.Lund@cablelabs.com> wrote:
>
>>      1.     The ability to accurately time the playback of different
>> media elements (for instance using wall clock time) in the document in a
>> declarative manner, i.e. without reverting to scripting in a way similar to
>> SMIL. MMT does not require a scripting engine.
>>
>>  I'm not sure why scripting is optional in MMT. Can someone familiar
>> with SMIL describe what declarative form they're looking for here?
>>
>>
>
> SMIL allows wallcock time synchronization through using wallclock times in
> @begin and @end attributes [1] within <par> and <seq> markup. It requires
> that the document "start" time has to be associated with a wallclock time
> and thus allows the mapping.
>
> JCD: Yes, that is what they mean when writing about SMIL.
>
>
>
> The closest effort to this at the W3C FAIK is the Web Animations work [2]
> which is planning to introduce a document timeline [3]. It's still in its
> early stages, so no browser implementation. Also, I don't know if it will
> satisfy the "declarative markup" requirement, because it only introduces a
> JS API for now. But it's probably well worth pointing out this effort to
> MPEG.
>
> [1]
> http://www.w3.org/TR/2005/REC-SMIL2-20050107/smil-timing.html#Timing-WallclockSyncValueSyntax
> [2] https://dvcs.w3.org/hg/FXTF/raw-file/default/web-anim/index.html
> [3]
> https://dvcs.w3.org/hg/FXTF/raw-file/default/web-anim/index.html#the-document-timeline
>
> --
>
> Overall, I do wonder about what MMT has to do with these application-level
> requirements. IIUC MMT is about delivering packed media, so it's an enabler
> of applications. It should not need to look at HTML & the JS APIs for
> defining its specifications.
>
> JCD: We have told the MMT group over and over that they are mixing layers,
> that their MMT architecture is a mess, etc.
> I have personally fought against this particular part of MMT, called
> Composition Information, for 2 years.
> Most of the people involved in the design of DASH have said the same.
> It seems the W3C liaison still did not help.
>

Fair enough. :-)

Silvia.