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RE: Track fragments

From: DENOUAL Franck <Franck.Denoual@crf.canon.fr>
Date: Wed, 17 Feb 2010 09:18:25 +0100
To: "raphael.troncy@eurecom.fr" <raphael.troncy@eurecom.fr>, "public-media-fragment@w3.org" <public-media-fragment@w3.org>
Message-ID: <40375B187E39BC4589F9C89097BD82A42528A37552@cressida.crf.canon.fr>
Hi all,

> -----Original Message-----
> From: RaphaŽl Troncy [mailto:Raphael.Troncy@cwi.nl]
> Sent: mardi 16 fťvrier 2010 19:30
> To: Davy Van Deursen
> Cc: 'Silvia Pfeiffer'; DENOUAL Franck; public-media-fragment@w3.org
> Subject: Re: Track fragments
> 
> Hi Davy,
> 
> > If we decide to add support for addressing multiple tracks, I think this
> > should be done based on a list of track names. Note that this is already
> > implemented within our NinSuna platform: when using track selection, we
> > mostly select more than one track using the 'tracks' selector:
> >
> > http://example.org?track='track1' : to address one track
> > http://example.org?tracks='track1';'track2' : to address multiple tracks
> 
> Why do you use 'tracks' instead of 'track'?
> What prevent you to use: #track='track1'&track='track2'?
> 
> > Do you mean by 'activating' that the server typically sends all the tracks
> > to the UA?
> 
> We might consider that in any case, the UA will receive a complete media
> file containing all the tracks and will decide to play (activate) some
> of these tracks specified in the URI.

This would be a fallback when server cannot extract the requested tracks, otherwise you get back to a "classical" fragment processing: whole resource transmission plus cropping/selection at client-side.

> I see the use case, where a media file contains multiple video tracks,
> has very borderline: how many files out there have such a property?
> 
> Serving only a number of tracks would be useful to save bandwidth if the
> video track is not served (e.g. audio + audiovision + subtitle for a
> blind user). But then, we would need a minus operator to tell the server
> ... send me this media file except the video track. How to express that?

What about =>
#track=include: audio(audesc,en),video(main,en),text(cc,en),text(sub,fr)
#track=exclude:audio(audesc,fr),(audesc, german), text(cc,fr), video(HD,en),
I think  media fragment syntax should enable to express (any) filter to apply on the resource.

(other 2 cents)
--
    Franck.

> 
> So the more I think, the more I tend to agree with Silvia that in most
> of the cases, we want to the UA to behave a certain way more than
> complex processing on server side. In particular when the track
> selection into a byte range request becomes a nightmare.
> I might be very wrong :-)
> My 2c.
> 
>    RaphaŽl
> 
> --
> 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 08:28:31 GMT

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