Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!shadooby!samsung!uunet!jarthur!cdouty
From: cdouty@jarthur.Claremont.EDU (Christopher Douty)
Newsgroups: comp.graphics
Subject: Re: Re: Workstations that can record/play realtime video
Message-ID: <3030@jarthur.Claremont.EDU>
Date: 14 Nov 89 23:53:55 GMT
References: <6509@portia.Stanford.EDU> <1360003@hpspcoi.HP.COM>
Reply-To: cdouty@jarthur.UUCP (Christopher Douty)
Organization: Harvey Mudd College, Claremont, CA
Lines: 25

In article <1360003@hpspcoi.HP.COM> jchristy@hpspcoi.HP.COM (Jim Christy) writes:
>
>> VHS quality 24 bits x 640 pixels x 480 lines x 30 Hertz x 3600 seconds
>> is 100 gigabytes uncompressed.

>This would imply that a standard VHS cassette tape has nearly 200 GB of 
>storage capacity.

>Jim H. Christy

	NTSC video is approximately 20Mb/sec, or at least that is what the
DVI people say.  I am inclined to believe that figure.  An hour of NTSC
video is then 20Mb/sec x 3600 sec = 72 Gigabytes/hour.  However a VHS
recorder only stores about half of the NTSC signal (maybe less), so the
standard t-120 tape holds about 72Gb worth of digital information (in analog
form) at its fastest play speed.

	I do think that 24-bit color is maybe a little excessive for VHS
format tapes, but it gives a stoarage prediction in the right ballpark.

				Christopher Douty       
			 cdouty@jarthur.claremont.edu

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