At 07:47 AM 1/20/98 -0500, you wrote:
>This is starting to sound to me like an argument that we oughtn't
>settle on a particular compressor at all within the core SAOL
>functionality, since applications will differ so widely in the
>functionality
>they need.
>
>If so, it's probably best just to dump the broken ones that are in
>the spec (not implemented yet) now. Arguments?
Agreed. Since you can patch together the components of a compressor with
an envelope follower and a table lookup, it should be up to the user to
come up with one. Maybe some example instruments could be provided.
One component of a compressor that is not specifically provided is a
dual-slope slew rate limiter. This is basically a portamento generator
that has a different rate depending on whether the input signal is going up
to down. This controls and "attack" and "decay" parts of the system, and
has other interesting uses as well. A module in the Serge Modular Music
System has something like this, called the "Dual Universal Slope
Generator", and it's nice for all kinds of controllable envelopes. This
might possibly be done with a ramp generator whose endpoints are altered
during runtime however.
The "compression" opcode as it reads in the core opcodes doesn't seem to do
compression, but waveshaping. It just seems to run a waveform through a
lookup table- all the compressors I know about include an envelope follower
in the circuit before the lookup table, then use the lookup table to
amplitude modulate the signal. Pcompress does this but doesn't provide
attack or decay controls. Maybe the envelope follower implied in the
buffer should have the attack and decay as optional parameters. Also since
you're running the gain through a lookup table you could compress, expand,
noise gate, or any other gain-controlled function, so it seems limiting
(forgive the pun :) to call it compression.
Steven Curtin
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Steven Curtin
http://www.emf.org/people_curtin.html
Lucent Technologies - Bell Labs Innovations
rm. 3C-208, 200 Laurel Ave S
Middletown, NJ 07748-4801 U S A
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