Subject: MAX Digest - 24 Aug 1998 to 25 Aug 1998
Date: Wed, 26 Aug 1998 00:00:00 -0400
From: Automatic digest processor 
Reply-To: MAX - Interactive Music/Multimedia Standard Environments
     
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There are 4 messages totalling 142 lines in this issue.

Topics of the day:

  1. Fast time-stretching with MSP? (3)
  2. CV-to-MIDI

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Date:    Mon, 24 Aug 1998 21:42:11 -0700
From:    jhno 
Subject: Re: Fast time-stretching with MSP?

>Is there a way to do such fast audio time-stretching with MSP?

i think the most straightforward and effective way to do this is to simply
vary the playback speed of the audio (from a buffer~, presumably), and
shift the pitch simultaneously to compensate for the variation. getting
this to sound good is a bit of a challenge...

the only pitch-shifting i know in msp is from ircam's "jimmies" collection,
or perhaps from a vst plugin. any others out there?

i have a denon dual-well dj cd player that does this - it can change both
speed and pitch of playback, and it has a mode where you can speed up and
slow down the piece without changing its pitch! it auto-corrects. it lags a
little if you change it too fast, but otherwise sounds quite good.

my eventude h-3000 also has some nice real-time pitch/time shifting.

good luck-
jhno

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Date:    Mon, 24 Aug 1998 23:32:02 -0700
From:    Les Stuck 
Subject: Re: Fast time-stretching with MSP?

>Imagine conducting a virtual orchestra: ... recording
>time-stretch
>user can influence the speed ...by "conducting"
>([using]...some MIDI ...device).
>loading, say, 1/4 second chunks of the digital
>audio recording into memory, and then stretch them

well, typically one would use 50ms chunks and lots of them and
call it granular synthesis. it works pretty well on
non-percussive orchestral stuff. a twisted example of granular
sampling using msp is at:
http://zeep.com/les/web/digi.html

i'm sure there are other techniques possible in msp, most of
which involving some sort of time-windowing scheme, but i bet
producing an accurate beat/tempo map from gestures is much
more difficult.

and tell me, who would enjoy conducting a virtual orchestra?
certainly not a conductor! so we're talking about something
like an installation or performance or a game in which
inexperienced people conduct, and that makes it even more
difficult to track tempo.

if you had a situation where a performer could rehearse with
the system, neural networks would certainly be interesting.
check out:
http://cnmat.CNMAT.Berkeley.EDU/MAX/neural-net.html

in any case, i wish you luck. if you get this to work, you'll
make millions in karaoke bars.

les

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Date:    Tue, 25 Aug 1998 10:43:00 +0200
From:    Oeyvind Brandtsegg 
Subject: Re: Fast time-stretching with MSP?

Just my 2 penniworth on the subject:

How about using an fft analysis/resynthesis approach ?
I haven't used MSP yet, because I currently don't have a machine good
enough to run it, but I've done fft resynthesis in realtime with Csound.
I then let a Dimension Beam (IR-sensor) directly control the time
progression of the sound. With this method I'm able to finely control
how the time parameter of the sound is affected.
I guess it would not be hard to implement that in MSP either.
Sound quality is largely dependent on hardware speed, though.

What would be the *real* cool thing is if you could fft-analyse in
realtime too, and do time-stretch of audio input.

And ,btw, I bet there is some way to get a fairly good tempo map from
gestural input, though I myself have never delved into that use.

Oeyvind Brandtsegg
mailto:obrandts@online.no

> >Imagine conducting a virtual orchestra: ... recording
> >time-stretch
> >user can influence the speed ...by "conducting"
> >([using]...some MIDI ...device).
> >loading, say, 1/4 second chunks of the digital
> >audio recording into memory, and then stretch them
>
> well, typically one would use 50ms chunks and lots of them and
> call it granular synthesis. it works pretty well on

>

[snip]

> i'm sure there are other techniques possible in msp, most of
> which involving some sort of time-windowing scheme, but i bet
> producing an accurate beat/tempo map from gestures is much
> more difficult.
>

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Date:    Tue, 25 Aug 1998 13:22:19 -0500
From:    Ed Hartley 
Subject: CV-to-MIDI

Quick question:

can anyone recommend a small, cheap, simple CV-to-MIDI converter? I want to
use it with a Yamaha FC-9 pedal, which has a 50k ohm impedance.

Thanks

Ed Hartley

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End of MAX Digest - 24 Aug 1998 to 25 Aug 1998
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