It's possible to make a good EQ using a chain of [equalizer]->[biquad~]s. equalizer is from GGEE and generates peak filter coefficients for biquad~. I've attached a 10-band eq that works pretty well, but the top and bottom bands should probably use lowshelf/ highshelf instead of equalizer.

Ben

On Friday 07 November 2003 12:37 am, David NG McCallum wrote:

Nick,

I was using one of the bp filters, which I think is a wrapper for the [filter~] object, so not the FIR~.

I was just trying to build an EQ to replace a VST plugin I'm using right now. The problem was that my performance patch is heavily based on the use of delays and whenever the feedback got really small the filters in the EQ that it was ultimately going out just started freaking out.

<sigh> Back to VST...

David . . David McCallum . Music wants to be free . http://mentalfloss.ca/sintheta .

Nicholas Mariette wrote:

...

Hi David,

I've recently had the same experience of unexpected high-CPU usage from FIR~ in Iemlib (under WinXP).

Which Iemlib filter have you had this experience with?

I found that I can run a maximum of about 8 FIR filters of 200samples length on a P4 2GHz. This does seem a little low for such a short FIR.

I tried recompiling Iemlib with MSVC++6.0 but I got no performance improvement. I haven't yet looked at the code or tried special compilers like the Intel compiler.

However, I have found that Ben Saylor's partitioned convolution external is somewhat more efficient for the same FIR filters. If you're referring to FIR filters, I'd try that external which can be found here. http://home.gci.net/~pamsaylor/ben/partconv~-0.1.tar.gz

And I'd be interested to hear of others' experiences with FIRs in PD. Anyone?

Nick

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aha! revenge of the denormals! i don't know if it has been dealt with in PD proper entirely. i just threw out a bunch of hip~ objects [which is "proper pd", and not an external, afaik] tonight because they were denormalizing like crazy every time they got zero volume.

as hans recommends, check through the list, there are some posts on denormals. one suggestion was to find an Intel C compiler for windows and compile the objects yourself. a quick fix is to run a small amount of noise through all the problem objects.

i think delays and filters in combination, and in that exact order [always a favorite for my live sets, and always bugging my machine out!], are about the highest risk of denormals ever.

d.

-=lowercase is beautiful -- e.e. cummings=-

Hans-Christoph Steiner wrote:

Sounds like the denormalize bug in P4s that causes the CPU to spike when a calculation is approaching zero. AFAIK, this problem has been addressed in Pd proper and some externals, so there should be example code out there. Check the archives of this list and pd-dev for more info.

.hc

On Mon, 3 Nov 2003, David NG McCallum wrote:

...

Dear All,

I had one of those CPU pig problems that I think I tracked down to the IEM filters not being optimised for P4s (just a guess).

Does anyone have IEMlib modified and compiled for P4 optimisation for Windows or...

Can anyone tell me that I'm wrong and that the IEM filters are an unlikely source of massive CPU consumption?

Cheers, David -- . . David McCallum . Music wants to be free . http://mentalfloss.ca/sintheta .

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zen

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