Xref: utzoo rec.audio:21774 sci.electronics:12267
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From: wiml@blake.acs.washington.edu (William Lewis)
Newsgroups: rec.audio,sci.electronics
Subject: Re: My CD player is running slow! (!)
Message-ID: <7248@blake.acs.washington.edu>
Date: 6 Jun 90 22:23:30 GMT
References: <1990Jun2.182334.21396@athena.mit.edu> <6378.26693284@umiami.miami.edu> <55024@microsoft.UUCP> <89@rhum.tcom.stc.co.uk>
Reply-To: wiml@blake.acs.washington.edu (William Lewis)
Organization: Clones `R' Us
Lines: 32

In article <89@rhum.tcom.stc.co.uk> iann@tcom.stc.co.uk (Ian Newman) writes:
>In article <55024@microsoft.UUCP> gordonl@microsoft.UUCP (Gordon LETWIN) writes:
>>
>>This is wrong.  Pitch shifting is easy.  My first CD player was an
>>inexpensive one and it had a pitch adjustment control on it.  It's my
>>guess that you can pitch shift just by changing the rate at which you
>>feed samples to the DtoA convertor. 
>
>This is wrong. Pitch shifting by spinning a CD faster is impossible. 
>If anythingit would only play the music faster, but at the same pitch.
>If your CD player did pitch shifting, it could only have done it at the
>analogue output stage, unless it had the appropriate DSP hardware in it, which
>I doubt.

  You didn't read what he wrote. He said nothing about spinning the disk
at a different rate. He was talking about clocking the D/A faster, 
which certainly WILL speed up the sound and increase the pitch, 
exactly like playing a record or tape at the wrong speed, as you would
know if you had ever done it by accident.
  Anyway, I was under the impression that the disk speed is
controlled by the FIFO length -- i.e., as the FIFO gets full, 
the disk slows; as it empties, the disk speeds up -- so the
only "real" regulation at all is the rate at which the FIFO
empties, i.e. the D/A's clock rate. 


>If anythingit would only play the music faster, but at the same pitch.
   I'd be surprised to find a simple way to do THAT without a DSP.

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