Xref: utzoo comp.graphics:2868 rec.video:3852 sci.electronics:3445
Path: utzoo!attcan!uunet!husc6!rutgers!mcnc!unccvax!dya
From: dya@unccvax.UUCP (York David Anthony)
Newsgroups: comp.graphics,rec.video,sci.electronics
Subject: Re: converting PAL to NTSC and back
Message-ID: <1048@unccvax.UUCP>
Date: 26 Jul 88 18:30:03 GMT
References: <10034@e.ms.uky.edu> <2922@nicmad.UUCP>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 43

In article <2922@nicmad.UUCP>, brown@nicmad.UUCP (Mr. Video) writes:
> In article <10034@e.ms.uky.edu> simon@ms.uky.edu (Simon Gales) writes:
> <What I want is a NTSC to PAL converter to be able to input NTSC into my
> <european frame grabber.   I would also like to go the other way (PAL to
> <NTSC) in order to record the output on an american (NTSC) vcr.

> The average cost for a good digital standards converter is $20,000.  I under-

> In other words, welcome to the world of non-standard video and big bucks!

	Assuming that the frame grabber is connected to your handy-
dandy Multibus, Unibus, or other trademarked-bus, with a general
purpose computer at the other end, it would seem trivial to me to
write a half-decent standards conversion program to operate on a
single frame. 

	Doing this fully-decent, though, would require a decent
computer, at least a MC68020 running single-user with cache enabled
doing a 2d FFT of an NTSC image (matrixed at 512 pixels squared)
takes a fairly long time. This, with the coprocessor too. (We just
got our hardware yesterday.  However, on an Omni-Byte OB68K1A with
MC68010 cpu and hardware coding, it takes tens of minutes. This,
though, without using lookup tables for sin(x), etc.)

	Virtually any manipulation looks like crap in the time 
domain (edge artifacts, etc.).  Real time standards conversion uses
the temporal aspect to hide the non-optimal conversion algorithms
in use.

	Image-Pro, from those guys up in Potomac, Md. running on 
a 286/287 pc with their own accelerator, ain't half bad for standards
conversion, but 'tis 'spensive. You could call Media Cybernetics
and ask them.

	Mr. Video is right.  Probably the best solution (for the wallet)
is either write your own frame conversion routines (and move mag tape
from machine to machine) or buy multirate VCR's.

	Converting NTSC to PAL within the same scanning system is 
trivial. Converting system B to system M is the hard part !!!!

York David Anthony
DataSpan, Inc.