Path: utzoo!utdoe!generic!pnet91!taob
From: taob@pnet91.cts.com (Brian Tao)
Newsgroups: comp.sys.apple2
Subject: Re: Soundsmith
Message-ID: <156@generic.UUCP>
Date: 12 Nov 90 06:15:08 GMT
Sender: root@generic.UUCP
Organization: People-Net [pnet91], Etobicoke, ON
Lines: 36

From THROOP@GRIN1.BITNET ("Throop,Henry B"):

> These two things go together.  Soundsmith varies the frequency of the note
> by simply playing the (fixed byte-length) sample at a higher or lower rate;
> notes on the left end are the same sample but played slower.  This causes
> the frequency to be lower, and because it takes longer to play the same
> number of bytes, the length is longer.  Varying the note length
> independently would entail either chopping off the sample after a length of
> time, or somehow compressing the same sample into a shorter time, with the
> same frequency. Obviously this can be done, as programs like synthLAB do,
> but I'm not sure exactly how that works.

    Your description of SoundSmith's sample playback is essentially correct. 
It simply speeds up or slows down the sample to produce the correct pitch,
hence the play time is either shortened or lengthened.

    More advanced sound generation software (like synthLAB) use multiple
samples of the same instrument to produce the sound.  These samples are taken
at different octaves, because you can't simply play back an instrument at a
higher speed to increase the pitch.  Every try playing a really high note
using the Piano in SS or Music Studio?  Instead of a high piano note, you get
this dinky little "plink".  Some people call this the "Mickey Mouse effect". 
Instead of speeding up a sample, synthLAB grabs the next higher sample of the
piano and plays it back, giving you truer sound.

    synthLAB can also sustain a note because you can specify how to loop the
two oscillators to produce an instrument.  It gets pretty technical at this
point (just look at Screen 2 of synthLAB...), so I won't try to explain it.  I
think this is how most professional synthesizers work.

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