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RE: Temporal fragments of media with time stamps

From: Davy Van Deursen <davy.vandeursen@ugent.be>
Date: Tue, 19 Jan 2010 08:04:08 +0100
To: "'Yves Lafon'" <ylafon@w3.org>, "'Jack Jansen'" <Jack.Jansen@cwi.nl>
Cc: "'Bailer, Werner'" <werner.bailer@joanneum.at>, <public-media-fragment@w3.org>, "'Richard Wright-ARCHIVES'" <richard.wright@bbc.co.uk>
Message-ID: <000401ca98d5$98c454a0$ca4cfde0$@vandeursen@ugent.be>
> -----Original Message-----
> From: public-media-fragment-request@w3.org [mailto:public-media-
> fragment-request@w3.org] On Behalf Of Yves Lafon
> Sent: maandag 18 januari 2010 11:54
> To: Jack Jansen
> Cc: Davy Van Deursen; 'Bailer, Werner'; public-media-fragment@w3.org;
> 'Richard Wright-ARCHIVES'
> Subject: Re: Temporal fragments of media with time stamps
> 
> On Mon, 18 Jan 2010, Jack Jansen wrote:
> 
> >
> > On 16 jan 2010, at 10:25, Davy Van Deursen wrote:
> >>
> >> Temporal fragments should indeed take into account embedded time
> stamps.
> >> Note that this is already stated in the specification [1].
> >>
> >> Best regards,
> >>
> >> Davy
> >>
> >> [1] http://www.w3.org/TR/media-frags/#processing-overview-
> interpretation
> >
> >
> > Thanks for finding this one!
> >
> > But: this means that we have to look through the protocol description
> with this in mind.
> >
> > If I have a video http://www.example.com/example.mp4, which has 10
> seconds worth of video, with timestamps 01:00:00:00 through
> 01:00:10:00, and a UA sends a request
> > with
> > 	Range: t:smpte=01:00:05:00-01:00:06:00
> > what does it get back in the Content-Range header?
> > I would assume the timestamps are as expected, but what is the
> duration
> > returned?
> 
> The duration should be the duration of the complete file, so 10s in
> this
> case. The fact that 10s and range is starting well over 10s is an
> indicator that the offset is not zero. Now... do we need to send the
> starting offset as well? (and if so using what kind of syntax).

Why do you think the duration is 10s? Shouldn't we respect the underlying
timing model of the container formats? Putting the above described example
in an mp4 player will, I think, result in 1 hour and 5 minutes nothing,
followed by 10 seconds media. Therefore, the total duration of this mp4 file
is one hour and 10 seconds IMO.

Best regards,

Davy

-- 
Davy Van Deursen

Ghent University - IBBT
Department of Electronics and Information Systems - Multimedia Lab
URL: http://multimedialab.elis.ugent.be/dvdeurse
Received on Tuesday, 19 January 2010 07:04:42 GMT

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