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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 08:23:03 +0100
To: "'David Singer'" <singer@apple.com>
Cc: "'Bailer, Werner'" <werner.bailer@joanneum.at>, <public-media-fragment@w3.org>, "'Richard Wright-ARCHIVES'" <richard.wright@bbc.co.uk>, "'Jack Jansen'" <Jack.Jansen@cwi.nl>
Message-ID: <000a01ca98d8$3d340e20$b79c2a60$@vandeursen@ugent.be>
> -----Original Message-----
> From: public-media-fragment-request@w3.org [mailto:public-media-
> fragment-request@w3.org] On Behalf Of David Singer
> Sent: maandag 18 januari 2010 2:38
> 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 Jan 18, 2010, at 8:06 , Jack Jansen wrote:
> >
> > On 16 jan 2010, at 10:25, Davy Van Deursen wrote:
> >>
> >> Temporal fragments should indeed take into account embedded time
> stamps.
> 'may', I think, surely.  It depends on whether the fragment time is
> expressed in NPT, or (say) SMPTE time-codes.  NPT starts at 0;  to
> resolve a fragment here, you're fine without inspecting the media.
> SMPTE time-codes, OTOH, need to be found.  They might not even be
> continuous in the media.

Hmm, what do you mean by 'need to be found'? Suppose an MP4 file starting
with an empty edit of 20s, followed by 40s video. What is the meaning of
t=npt:0,30 and t=smpte:00:00:00:00,00:00:30:00? IMO, they will both result
in an MP4 file starting with an empty edit of 20s, followed by 10s, no?

Best regards,


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 07:23:36 GMT

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