*BSD News Article 27772


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From: hasty@netcom.com (Amancio Hasty Jr)
Subject: Re: Video output
Message-ID: <hastyCLsz1J.GDu@netcom.com>
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
References: <CLq9pt.Mps@cogsci.ed.ac.uk> <2kjd5f$g32@dingo.cc.uq.oz.au>
Date: Fri, 25 Feb 1994 23:10:30 GMT
Lines: 56

In article <2kjd5f$g32@dingo.cc.uq.oz.au> ggm@dingo.cc.uq.oz.au (George Michaelson) writes:
>richard@cogsci.ed.ac.uk (Richard Tobin) writes:
>
>>I'm looking for some hardware that will allow me to record the display
>>on a PC onto videotape (VHS/PAL).  I will be running XFree under
>>NetBSD.
>
>>What are the options for doing this?  Will I have to reduce the PC
>>display resolution to that of the video?  I'm willing to get either an
>>external adaptor or a replacement video card, so long as it works
>>under X.
>
>Forgive me if this is wrong... Its my understanding...
>
>You need either a card with an explicit video output akin to the
>(very expensive!) Galileo board on the SGI, or a generic sync rate
>converter, which is a black box that plugs into the monitor flyleads
>and performs the decimation/rate conversion and provides flyleads for
>input to suitable recording/mixing media. (SVHS plug, BNC RGB+sync, whatever)
>
>VHS recorded tape and broadcast TV is around 15Khz. horizontal sync.
>VGA is 35Khz, SVGA/Sun/Dec/Etc is 60, 65, 72, 100+ Khz. You can't get
>from this to 15Khz without loosing information. Typically you either
>select a zone of the screen for full pixel recording at the appropriate
>width x height 1:1 or else do some kind of decimation. a 1024x768
>window cut down to the VHS is going to look ok, but definately not
>PIXAR quality. It beats the hell out of pointing a camera at the screen
>mind you...
>
>A sync rate converter for VGA->VHS is around $10k Australian. If you want
>from 72+Khz its more like $40k Australian. I suspect a video toaster card
>will be cheaper but quality will be an issue, as well as getting a NetBSD
>driver. You can probably hire a sync rate converter from a mob doing
>TV O/B production work, but you definately need to know the horizontal refresh
>rate of the local monitor, and pinouts of the connectors. You can often
>use Thinwire and T-pieces but remember Thinwire is 50 Ohm and TV is 75 Ohm
>so you loose if the runs are too long.
>
>
>Why not persuade SGI to loan you an Iris with Galileo, and use remote X
>to get the NetBSD box to display onto the Iris which can then drive the
>tapedeck directly? It'll only cost around $150k to buy the setup :-)
>

Or he can call up Fry's Electronic in Palo Alto, Ca. and get a video
convertor box for his PC for around $150 so much for SGI :)

	Amancio



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