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From: madler@nntp-server.caltech.edu (Mark Adler)
Newsgroups: comp.compression
Subject: Re: Sound compression
Keywords: sound compression
Message-ID: <1991May23.215341.7836@nntp-server.caltech.edu>
Date: 23 May 91 21:53:41 GMT
References: <91May15.140250edt.750@neuron.ai.toronto.edu> <105539@sgi.sgi.com> <1991May23.123202.18335@cc.tut.fi>
Organization: California Institute of Technology, Pasadena
Lines: 20


Just thought I'd throw into this thread that Sony has announced a 2.5 inch
CD format that puts 74 minutes of music in about 175M using 5:1 compression.
They are using psychoacoustic techniques, which means they are throwing
away subband information that it masked by other subband information based
on experiments with human frequency masking.  It will be interesting to
see the audiophile reaction to this.

Sony says that this is their best shot at audio compression currently, and
that more than 5:1 was unnacceptable.  They have 1Mbit of ram in the design
to buffer three seconds of sound to account for compression variation,
tracking loss, and other glitches and come out continuous and uninterrupted.
(The player actually keeps going for three seconds after you pull out the
CD!)

This is not the same as the format they are proposing for MPEG sound
compression, implying that the MPEG proposal is older and not as good.

Mark Adler
madler@tybalt.caltech.edu