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RE: RE : [Moderator Action] Bugs and TT (was TT and subtitling)

From: Glenn A. Adams <glenn@xfsi.com>
Date: Thu, 6 Feb 2003 11:44:21 -0500
Message-ID: <7249D02C4D2DFD4D80F2E040E8CAF37C01FB14@longxuyen.xfsi.com>
To: <Johnb@screen.subtitling.com>, <joeclark@joeclark.org>
Cc: <public-tt@w3.org>

> -----Original Message-----
> From: Johnb@screen.subtitling.com 
> [mailto:Johnb@screen.subtitling.com] 
> Sent: Thursday, February 06, 2003 3:19 AM
> To: joeclark@joeclark.org
> Cc: public-tt@w3.org
> Subject: RE: RE : [Moderator Action] Bugs and TT (was TT and 
> subtitling)

> By subtitling I am referring to my admittedly narrow 
> perspective of subtitling and captioning of broadcast video. 
> I have looked at SMIL and Quicktime and cannot see how to 
> reconcile the timing aspects of these standards with the 
> timecode in an external broadcast signal (where the timecode 
> may be discontinuous due to advert insertion). Comments please?

It is necessary to distinguish between media play time, such as
represented by the NPT mechanism, and a broadcast transport
stream's program clock reference (PCR). The latter (PCR) is indeed
discontinuous at insertion in/out points; however, the former (NPT)
is not.

In the context of SMIL, it is generally the media time that is
used when expressing syncbase offsets.

Received on Thursday, 6 February 2003 11:44:25 UTC

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