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From: poirier@dg-rtp.dg.com (Charles Poirier)
Newsgroups: comp.sys.amiga
Subject: Re: Neptune Pictures
Summary: Sound compression
Message-ID: <1808@xyzzy.UUCP>
Date: 12 Oct 89 20:29:57 GMT
References: <24659@louie.udel.EDU>
Sender: usenet@xyzzy.UUCP
Reply-To: poirier@dg-rtp.dg.com (Charles Poirier)
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Organization: Data General Corporation, Research Triangle Park, NC
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In article <24659@louie.udel.EDU> new@udel.EDU (Darren New) writes:
>I understand that the Neptune pictures are too large to post.
>Could somebody please convert the sounds that Voyager heard to
>IFF-8SVX format and post these?  I'm sure that these would take
>much less bandwidth, especially with modern compression techniques.

Most "natural" sounds do not compress well using normal (LZW-type)
compression.  There are no "runs" of the same sample value, and the
values are pretty evenly distributed.  You *can* get somewhere by using
Fourier transforms, but (a) it's slow for a non-accelerated machine
to do these transforms and (b) some transform-compression techniques
result in a non-exact (though reasonably recognizeable) decompression.

The appropriateness of such a posting is problematical.  Say 20KHz
of 8-bit samples, negligible compression, that's about 3 seconds of
sound per canonical 60KB Usenet posting.  I would "just say no" IMHO.

	Curmudgeonly yours,
	Charles Poirier