From: brown@vidiot.UUCP (Vidiot)
Newsgroups: rec.video
Subject: Re: CAV variable frame rate? (was Re: CAV vs CLV)
Date: 30 Sep 92 05:46:01 GMT
Reply-To: brown@vidiot.UUCP (Vidiot)
Organization: Vidiot's Hangout

In article <summer.717719859@mamura> summer@mullian.ee.mu.OZ.AU (Mark Summerfield) writes:
<Here's one thing I didn't see mentioned in any of the articles on CAV vs CLV
<here. This may be because it's not true :-) Can anybody independently verify
<this? Here goes:
<
<According to an article in a local newsletter recently, CAV discs can be played
<at any frame rate, i.e. they are not restricted to 25/50 frames/sec PAL and
<30/60 frames/sec NTSC. The article claimed (on the basis of stopwatch trials
<with a computer controlled LD player playing a defined number of frames from
<a CAV disc) that some Criterion CAV titles actually ran at 24 frames/sec.
<This is the frame rate used for film, of course. The implication of this
<is that CAV discs may be mastered direct frame-for-frame from the original
<film, the reduced processing resulting in better picture quality. If true,
<this would give CAV (particularly letterbox format) a distinct advantage
<of CLV, since there would be virtually no processing of the image in
<transferring to disc.
<
<The article claimed that "most" modern TVs would have no problem with this
<since they sync automatically to the incoming frame rate. Personally,
<I don't belive this -- *I* would certianly know it was happening (if I
<had any CAV discs to try it on :-). My (Hitachi) TV (remembering I'm
<in a PAL country here) syncs perfectly to 50 frames/sec on all its
<RF channels, but rolls if fed the 60 frames/sec PAL-colour converted
<NTSC from my LD player. A vertical hold control would probably fix this...
<if it had one. Instead it has a (undocumented!) AV channel which syncs
<perfectly to 60 frames/sec (and a good thing, too!), but rolls if
<fed the 50 frames/sec PAL video from my VCR! This means I have to select
<a different channel depending on whether I'm viewing a PAL or NTSC LD
<(which is more convenient than playing with a vertical hold control,
<but less convenient than having a more expensive TV which would do the
<job automatically). It also means that if I stuck in an NTSC disc
<running at 24 frames/sec, I would probably be surprised to find that
<I had to select the channel I normally use for watching PAL to get
<it to sync properly.

Who the Hell are these people?  They are idiots.

Videodiscs are a video medium and as such must record at the rate of the
country it is used in.  TVs cannot except video rates of 24 frames a second.
They would croak and you would get a picture that rolls, alot.

You need to give these idiots a copy of the laserdisc FAQ.  They need to know
how a laserdisc, especially a CAV disc of a movie.

In a nutshell, it just appears like the CAV disc is running at 24 frames.
There are little flags that tell the laserdisc player where to stop.  These
"white" flags are set to stop on a film frame.  The laserdisc frame counter
gets its information from the VBI and it too is programmed at 24 frames.

Get the correct information to these idiots.  They are spreading false
information that needs to be stopped, NOW.  Get them Bob Niland's goodies.
-- 
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