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From: dsi@unccvax.UUCP (Dataspan Inc)
Newsgroups: net.video
Subject: Re: NTSC<->PAL
Message-ID: <457@unccvax.unccvax.UUCP>
Date: Tue, 25-Mar-86 09:24:11 EST
Article-I.D.: unccvax.457
Posted: Tue Mar 25 09:24:11 1986
Date-Received: Thu, 27-Mar-86 07:12:37 EST
References: <8603131714.AA19694@seismo.CSS.GOV>
Organization: UNC-Charlotte
Lines: 43

> NTSC video is a 525-line, 30 frame format with each frame made up of two
> fields.  The field rate is 59.94 fields/sec.  PAL is totally different,
> not only with a different field rate, but a different line format.  PAL
> standard is around 600 lines if I remember correctly.  In summary, it's
> a real pain to convert the stuff.  There are several production companies
> in New York which specialize in converting video from-to various formats.

     (Once again) PAL has NOTHING TO DO WITH LINE AND FIELD FORMATS. NOTHING.
There is indeed a standard known as PAL-M which uses NTSC scanning rates 
and simply adds the logic and delay line circuitry required to cope with
opposite phase burst on every line.

     System M is 525 lines, 60 fields/sec, 2:1 interlace
     System B is 625 lines, 50 fields/sec, 2:1 interlace

     System M is utilised in the United States, Canada, etc. and typically
uses NTSC as its colour system
     System B (and its variants) is utilised in the UK, etc; and typically
uses PAL as its colour system. 

     So, if you want to discuss conversion, let's use the correct terminology
NTSC-M to PAL-B (or whatever). The conversion in component form (RGB or YIQ)
from M to B is nontrivial but not horribly expensive; I expect the next 
generation of standards converters to cost under $20,000. (You can now buy
a frame store TBC for under $5,000 including rudimentary digital video
effects!!) Composite (encoded) form conversion is not possible at the present
state of the art, and why would anyone want to in the first place??

    Actually, the colour system is irrelevant except in the case of SECAM 
to NTSC (which requires additional temporal processing due to that stupid
line multiplexing technique -- I don't care if the sets don't have a hue
control ) because all conversions are performed RGB or YIQ.

    There are other 625 line systems out there, but the suffix letter refers
to the luminance bandwidth and audio subcarrier frequency.  The 819 line 
standard is, I believe, obsolete (or rapidly becoming so) to permit interchange
of videotape amongst members of the EBU.

Keeping NTSC the best television system in the world...

David Anthony
Director of Engineering
DataSpan, Inc