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From: ron@brl-smoke.ARPA (Ron Natalie <ron>)
Newsgroups: net.audio,net.analog,net.graphics
Subject: Re: Digital audio - sample rate conversion
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Date: Sun, 2-Mar-86 00:48:58 EST
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Posted: Sun Mar  2 00:48:58 1986
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> There has been some discussion recently about digital audio tape formats,
> and about how sampling rates are being made purposely incompatible with
> the Compact Disc standard, presumably to prevent verbatim high-quality
> copying.  This raises a question - what techniques could one use to
> implement a clean conversion from one sample rate to another - either
> upward or downward, without converting back to analog and then re-digitizing
> at the other rate?

Actually converting to analog won't necessarily help either.

> Intuitively, I can more-or-less grasp the use of an FIR digital filter to
> interpolate in the Philips 4x "oversampling" CD playback filter system.  What
> happens if you are not resampling to a convenient integer multiple of the
> original rate?  Would a similar technique be applicable for increasing
> or decreasing the sampling by non-integer factors?  Resampling to a decreased
> rate is particularly baffling.

You could use the least common multiple sample rate :->