Path: utzoo!utgpu!watmath!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: comp.graphics
Subject: Re: RGB to NTSC converters
Message-ID: <18063@onfcanim.UUCP>
Date: 29 Apr 89 02:45:17 GMT
References: <2441@helios.ee.lbl.gov> <3265@eos.UUCP>
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Distribution: na
Organization: National Film Board / Office national du film, Montreal
Lines: 18

>> It is possible to encode RGB
>> signals whose source cannot be locked to external sync, but this can be
>> expensive,
>
>This could alternatively be done using a sync generator that
>accepts an external genlock signal.  While it would be preferable
>to have the sync generator be the master, this can give acceptable
>results if the RGB source to which you are locking is sufficiently
>stable.

For really "broadcast quality" video, the colour subcarrier has to
be locked in phase to sync.  If you use the sync generator as a master,
you automaticallly have this.  If you use the framebuffer as the master,
most sync generators will lock their sync to the framebuffer's, but let
the subcarrier free-run, so that sync and subcarrier are unrelated.

This is what 1/2 inch and 3/4 inch VCR's produce anyway, so it's good
enough for many purposes, but is isn't fully "standard" NTSC.