W3C home > Mailing lists > Public > public-media-fragment@w3.org > February 2010

Re: Track fragments

From: RaphaŽl Troncy <raphael.troncy@eurecom.fr>
Date: Wed, 17 Feb 2010 15:14:21 +0100
Message-ID: <4B7BF9BD.2070905@eurecom.fr>
To: Davy Van Deursen <davy.vandeursen@ugent.be>
CC: 'Silvia Pfeiffer' <silviapfeiffer1@gmail.com>, 'DENOUAL Franck' <Franck.Denoual@crf.canon.fr>, public-media-fragment@w3.org
>> Why do you use 'tracks' instead of 'track'?
>> What prevent you to use: #track='track1'&track='track2'?
> Because that might not be compliant to our grammar :-)?

Well, we don't consider 'tracks' with an 's' either in the grammar :-)

We have discussed in today's telecon that we would not like to allow 
something like: <uri>#t=30,90&t=10,15. More generally, we don't want 
that the time or the space dimension is specified more than once in the 
fragment because we don't want to bother trying to understand what does 
it mean. The question remains for the track dimension, since it is 
reasonable to restrict a media file to a number of tracks.

I see (at least) two points to resolve:
   - What are the changes we need to make (if any) in the grammar to 
allow a selection of multiple tracks in a fragment? Silvia has proposed: 
#track="audio(audesc,en);video(main,en);text(cc,en);text(sub,fr)" ... a 
semi-colon separator
   - What is the semantics of the fragment when one or multiple tracks 
is specified in a fragment? Does it mean *only* the tracks selected 
explicitly in the fragment? In other words: 
#track="audio(audesc,en);text(sub,fr);" will not contain video but just 
an audio and subtitle tracks?

> The only reason was
> that I wanted to keep the identifiers currently specified by the group as
> they were. That can be easily changed of course, it's just a matter of
> syntax sugar I guess. As a side note, similar to 'tracks', we also have the
> 'ts' identifier which can be used to identify more than one time range
> (e.g., #ts=0,10;20,30) but I think multiple time ranges is less relevant for
> us right now.

And what does it mean? Is it an union? An intersect? An incluion (out of 
range in this case)?


RaphaŽl Troncy
EURECOM, Multimedia Communications Department
2229, route des CrÍtes, 06560 Sophia Antipolis, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.eurecom.fr/~troncy/
Received on Wednesday, 17 February 2010 14:15:24 UTC

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