[PD] iemlib-filters and Pentium-NaNs
musil at iem.kug.ac.at
Fri Jul 19 01:57:50 CEST 2002
did anybody watch this phenomenon:
the CPU is a PII 800 MHz;
I tried under w2k and linux;
a patch with some sample-loops and LFOs consumes 50% cpu-power.
adding some (10 .. 20) filters of iemlib (like hp1~) it eats up to 100 % (after 5 minutes).
in my test-patches, one filter takes about 0.1 to 0.2 %.
I figured out, if there is no signal in, the IIR-filters produce NaNs.
I think, Miller wrote in his sources of "d_filter.c" a NAN-protection.
but it did not work very well for me.
I added to each filter a white-noise-signal multiplied by "*~ 1e-10" (-200 dB),
now the filters are cpu-power-stable. (I generate only once, and then i sended it with s~ and
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