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Why use time as a unit of measurement? (was: Proposal 0.0)

From: <lists@wiltgen.net>
Date: Tue, 11 Feb 2003 20:04:06 -0800 (PST)
Message-ID: <62646.66.127.210.130.1045022646.squirrel@webmail.wiltgen.net>
To: <public-tt@w3.org>

Johnb@screen.subtitling.com wrote...

> FileX is indexed against the timecode that is stored as VBI data on TapeX.
> So unlike SMIL - the media are separate - subtitles in one - video and
> audio on another.

You can forget about SMIL, although I think that understanding what it is
a useful prerequisite for anyone who wants to contribute.

Unless I'm missing something, Proposal 0.0 works just the way you would like
-- subtitles in one file, video and audio in another.

> In practice, the broadcaster will want to show adverts. These can occur
> at **any time** during the broadcast, and may differ from showing to
> showing...

In my previous post I described how this would work.  (Please let me know
if the explanation didn't make seise.)

> Subtitles are frame accurate for lip synching.

I've explained a few times why time (rather than frame-based timecode)
must be used.  As two examples, the TT should still work when taking a
24fps film source to NTSC, or to the web via a QuickTime movie with a
default timebase of 600 units/second whose video content is encoded at
12fps.

> I can conceive of other situations where the assumption of 1 sec per sec
> is invalid.

I know you're not serious, but I don't get the joke.

> ...timebases can always be converted into a single format.

Exactly, and that single format is time.

-- Charles Wiltgen
   <http://playbacktime.com/>
Received on Tuesday, 11 February 2003 23:04:07 GMT

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