NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/unix/question/10814

Internet Message Format | 1992-09-08 | 1.9 KB

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From: [e-mail] (Martin McCormick)
Subject: Re: Playing CD in workstation A, hearing it in B, Can I?
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Organization: Oklahoma State University, Stillwater, OK
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Date: Tue, 8 Sep 1992 05:24:06 GMT
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if there is a utility that will play a CD on a Sun Sparc, it must be a
pretty sophisticated one.  CD's use 14-bit audio samples encoded with the
Reid-&-Solomon error correcting codes  at a sampling rate of 44.1KHZ for
each channel.  The audio channel on a Sun Sparc is an ISDN telephone
subscriber IC which operates at a nominal rate of 8 thousand samples per
second.  Its digital samples are actually 12-bit samples, but the I/O works
in 8-bit samples, each one representing the change of audio level which
occurred between the present sample and the one just before it.  The samples
represent logarithmic values rather than linear ones.  This is to give the
chip the ability to handle large ranges of sound level.  The chip is capable
of operating using the Mu-Law or the A-Law method of piece-wise level handling.
In the U.S., ISDN telephones use Mu-Law conversion so the drivers that come
with Sun Sparcs are Mu-law.  Many other countries use A-Law conversion so
the binary sound files should take this into consideration when producing
a stream of samples to be sent to the ISDN chip.
    The bottom line, here, is that any utility to properly do this needs
to be a very sophisticated program.  It will probably also really eat CPU
time if it runs in real-time.

Martin McCormick WB5AGZ   Stillwater, OK
O.S.U. Computer Center Data Communications Group