[PD] readsf~ harddisc access

[derek holzer]

Johannes Burström wrote:

> today I experienced it again,  with a very 
> simple patch - just a rather large soundfile played back by readsf~ fed 
> into a munger~. After a sound breakdown with pd cpu usage spiking up to 
> 97%+ i decided to defragment my drive, after which everything  went as 
> it should, and still is. so i have a few questions:

Please don't neglect the fact that munger~ is a *very* CPU intensive 
patch when you start to have lots of grains with very small windows. 
I've crashed PD many times with it [inspiring me to make my own 
granulating delay line instead.]

> Does this (harddisc access problems = total audio breakdown) make any 
> sense, or is it just a coincidence? after playing some live gigs with 
> pd, i'm starting to believe in fairies and ghosts.

You might examine other possibilities as well. One big one is if you 
have a Pentium 4 processor. I've been fighting with CPU spikes in PD for 
a very long time now, and often find them related to denormal numbers. 
These are numbers very close to absolute zero, but not quite there, and 
are characterized by an extremely long series of digits after the 
decimal point, and which kick a P4 CPU into extremely slow and accurate 
mode. I found the problem to be much worse under Linux, but that doesn't 
mean it doesn't exist under windoze.

Otherwise, yes, HD access could slow up your DSP a bit, although readsf~ 
is designed to minimize that much more than loading audio all at once 
into a table. I'll let one of the real gurus here tackle that part of 
your question in more detail ;-)


d.



-- 
derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 161:
"Trust in the you of now"