I've often kind of wondered about the many issues that arise from the whole ksmps issue. What should it be, how does it affect the sound, etc. So many opcodes now seem to operate best (sometimes only) if ksmps = 1, so has any thought been given to making future versions of CSound always have ksmps = 1, thereby basically making it go away altogether? I understand it's there and configurable for performance reasons, but the (often minimal) performance gains seem overshadowed by the confusion the distinction often causes. If ksmps always equalled one, then there really would be no need to distinguish between k and a-rate variables at all. It would simplify things immensely.

Of course, I defer to the developers on this issue, and it would represent a fairly radical change. But it's at least an intriguing idea.

Michael Bechard



----- Original Message ----
From: John Lato 
To: csound@lists.bath.ac.uk
Sent: Monday, July 7, 2008 12:44:54 PM
Subject: [Csnd] Re: a-rate if

Joseph Sanger wrote:

> 2. Is there another opcode which I've overlooked? Like the 'a' opcode,
> but in reverse; something which simply copies the a-rate variable to
> k-rate every ksmps, without averaging or finding the maximum.

In general this isn't possible.  Since an a-rate variable is an array of data (with 
length ksmps), it's clear that to convert from a-rate to k-rate you need some sort of 
aggregating function (e.g. calculate the average or maximum).  In the special case of 
ksmps=1 aggregating is unnecessary, but both averaging and taking the maximum would 
return the same value then anyway, so it doesn't make any difference.

I agree this can seem inelegant to many csound users, but if you think of how the 
orchestra is interpreted by csound it should be clear.

>
> 3. Is there any reason why 'if' can't be made to accept a-rate variables
> in the (near!) future?
>

I can think of several.  Again, understanding that an a-rate variable is really an 
array should make it clear.  Csound operates at the k-rate.  'if' accepting a-rate 
variables only makes syntactic sense in the case of ksmps=1, all other values would 
mean creating separate execution paths within a single a-variable array.  I doubt 
that could be implemented in any fashion that doesn't defeat the purpose of the 
k-rate (which means that ksmps=1 is what you really want anyway).

Working at ksmps=1, I would use max_k as you are already.  Downsamp and interp are 
other options.

John W. Lato
Sarah and Ernest Butler School of Music
The University of Texas at Austin
1 University Station E3100
Austin, TX 78712-0435
(512) 232-2090


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