Subject: Re: [linux-audio-dev] Extending LADSPA to support Non-Causal Plugins
From: Jarno Seppanen (jams_AT_cs.tut.fi)
Date: Mon Oct 30 2000 - 11:52:59 EET
"Richard W.E. Furse" <richard_AT_muse.demon.co.uk> writes:
> Non-causal is a signal processing term, but I do agree it isn't terribly
> intuitive or especially well-defined. I'm very open to suggestions!
IMHO causality is a well-defined and very nonambiguous property -- if you do
signal processing that is. From Oppenheim, Schafer, Discrete-Time Signal
Processing, 1989, p. 20: "a system is causal if for every choice of $n_0$ the
output sequence value at index $n = n_0$ depends only on the input sequence
values for $n \leq n_0$." ... "That is, the system is nonanticipative."
For example, according to the definition, the reverse operation is not
causal, since there exist output values at $n = n_0$ that depend on input
values at $n > n_0$.
However, not being a native speaker I don't know of the connotations of the word.
-- -Jarno
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