[Tig] wow + flutter

Wilf Giovanella wgiovanella at rogers.com
Mon Aug 25 05:12:52 BST 2008


Graham Collett wrote:
> 1980 subscribers as of August 2008
> Sohonet ( http://sohonet.co.uk ) supports the TIG
> Eric Maurer supports the TIG
> http://www.colorist.org/wiki3
>  ====
> 
> 
> For the same reason that a film can run on a telecine and still be
> unstable ... Multiplied by 2 for the same problems on the sound follower
> ..and then combined with synchronsining slackness/errors and hey presto.
> I believe the Magnotech has the tightest sync .. Cintel ferrit even
> though was very good down to a 1/4 frame sync was only driven by 1ppf
> ... 
> 
> Graham Collett
> Sprockets(telecine) Ltd
> www.sprockets-telecine.co.uk
>  
> 
> 
> -----Original Message-----
> From: tig-bounces at tig.colorist.org [mailto:tig-bounces at tig.colorist.org]
> On Behalf Of Rob Lingelbach
> Sent: 24 August 2008 20:04
> To: Group Internet Telecine
> Subject: [Tig] wow + flutter
> 
> 
> 1980 subscribers as of August 2008
> Sohonet ( http://sohonet.co.uk ) supports the TIG
> Eric Maurer supports the TIG
> http://www.colorist.org/forums
>  ====
> 
> 
> I've always wondered, if a mag track is locked to a telecine, and the  
> reference is regular, how can audio (noticeable particularly on piano  
> tracks) flutter?
> 
> Once long ago I think it was Dave Tosh who told me there really is no  
> complete guarantee that the speed is constant.
> 
> --
> Rob Lingelbach
> rob at colorist.org    http://www.colorist.org/robhome.html
> 
> 
> 
> 
> _______________________________________________
> http://www.colorist.org/wiki3
> 
> 
> _______________________________________________
> http://www.colorist.org/wiki3
> 
I have found that if the telecine is generating biphase with a sprocket 
drive, then anything in the film path after the capstan can affect the 
mag follower, this includes PTRs.
If the capstan servo is generating the biphase for the follower, then 
the flutter is a factor of the follower's servo and how tight it is 
locked to the biphase.
I have seen this on all followers, that are driven by biphase, mag, 1/4" 
and hard disk systems.
If the telecine uses scan tracking or any such patch shifting to reduce 
burn, then the film is slowly shifting phase, following the patch.  You 
can confirm this by comparing the timecode on follower when locked to 
the telecine, with video frame sync.  The sync word will shift as the 
scan track shifts.  Depending where the sync word is relative to the 
video frame, you may see a timecode error.
Have you ever wondered why sometimes audio durations are off by 1 frame?

Wilf Giovanella
Deluxe Postproduction
Toronto




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