Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!ox.com!emv
From: doug@eris.berkeley.edu (Doug Merritt)
Newsgroups: comp.archives
Subject: [comp.dsp] Re: Video and Audio Compression (software and hardware)
Message-ID: <1991Jan29.205154.14824@ox.com>
Date: 29 Jan 91 20:51:54 GMT
References: <331@frcs.UUCP> <1991Jan29.172835.8394@agate.berkeley.edu>
Sender: emv@ox.com (Edward Vielmetti)
Reply-To: doug@eris.berkeley.edu (Doug Merritt)
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Archive-name: graphics/pixutils/jpeg/1991-01-29
Archive-directory: think.com:/jpeg/ [131.239.2.1]
Original-posting-by: doug@eris.berkeley.edu (Doug Merritt)
Original-subject: Re: Video and Audio Compression (software and hardware)
Reposted-by: emv@ox.com (Edward Vielmetti)

In article <331@frcs.UUCP> paul@frcs.UUCP (Paul Nash) writes:
>
>I need as much information as I can lay my hands on about video
>and audio compression. [...]
>Unfortunately, our newsfeed is erratic at times [...]

Well, mail didn't get through to you, either, so I'm posting my reply:


The fairly new method of DCT (discrete cosine transform) video compression
will probably interest you. There are apparently both lossless and lossy
forms, and it is the basis for the new (or under-development?) and famous
JPEG video compression standard.

I know very little about it (although I intend to learn more), but some
useful information:
	1) There's a theoretical math book on the subject, titled
	   "Discrete Cosine Transforms". Sorry, I haven't seen the contents,
	   just spotted it in a university book store in the math section.

	2) There's some free software that performs DCT's in various
	   ways (JPEG and otherwise, "fast" and otherwise),
	   available via anonymous ftp from think.com, in subdirectories
	   of /jpeg. This is probably your best bet, since it seems to
	   represent good work by members of some kind of mailing list
	   or working group on the subject, and DCT & JPEG are apparently
	   state-of-the-art. I just discovered this archive a few hours
	   ago, so I haven't had a chance to try any of it out yet.

I have reason to think that similar methods may be effective for audio,
but since I haven't "done my homework" on the subject yet, I'm not positive.

By all means, please summarize everything you learn about for the net.
Thanks,
	Doug
--
	Doug Merritt		doug@eris.berkeley.edu (ucbvax!eris!doug)
			or	uunet.uu.net!crossck!dougm