nVidia CUDA GPU computing PC FIR

[toffer]

Hi there,

great job so far, though i can't use it yet without that new GPU i want
have you ever thought about making a VST-plugin out of your solution?
Steinberg VST features high level multichannel input and output streaming.
It integrates perfectly into most professional audio editing programs on the market.
Howewer, VST3 has not as many host applications yet, so VST2.4 would be the better choice here. They provide nice SDKs for both and even for host application development and for ASIO-drivers.
You could use your code in a studio environments for music (DVD-) production as well as a digital mixer in a DJ-Setup.
I would love to see the massive power of CUDA integrated into my music production software.

Greetz
Toffer

[KOON3876]

Hi, I downloaded Steinberg SDK before, and found that we can not post source code. So I made my own programs.
I can not support each one user, so I throw whole source codes to www. (When I make VST plugin as binary, I have to modify and modify and version up and up..)

also I have poor experience on studio, audio professinal area.

[Theo404]

The FIR coefficient generator in your package is nice, thanks for sharing, I really like the EQ feature... however, I cant seem to make a filter with it that doesnt 'ring' horribly, changing kaiser window doesnt seem to do anything to the slope, as does reducing the target stopband attenuation, many attempts with different values of taps, alpha and attenuation all seem to result in increadibly steep cut off slopes... am I missing something obvious?

Many thanks.

[Theo404]

Just a quick arta grab to show what I mean, the low pass had a kaiser alpha value of 8 and a target stopband atten of -60db, the high pass has a kaiser alpha value of 16 and a target stopband atten of -100db, the cutoff slope is exactly the same.... ??

[KOON3876]

Hi you mean you want to have smooth filter slope?
I think you have to reduce TAPS to 128 or 64 or 32, to get slow-roll-down slope.
Kaiser is to get high stopband attenuation.

Long Tap FIR filter is to get steep filter, so maybe you should use IIR filter? Then you can get 6/12/24 dB/Oct smooth filter.

[Theo404]

I thought kaiser window defined slope as well as stopband attenuation? I dont mind a 100db/octave filter, but the ones produced by your program seem to make filters with a much higher slope than that, moving 10-20db down within a few hertz.... I have searched through the source to find a variable to change to make the filter slope less sharp, couldnt find anything that worked....

Using DPS links, increasing the kaiser window alpha value not only increases stopband attenuation, but makes the curve less steep.

Have you not experienced 'ringing' with the filters from your program? To me its very audable.... but it could be something else wrong......

[KOON3876]

Attached shows TAPS (512 vs 8192), 512TAPS makes slow filter.
lower chart shows effect of Kiser, it controlls side curve.

ringing means Mid speaker has some high-frequency noise?
I don't have any....

[Theo404]

I thought the number of taps in a filter affected frequency resolution, which allows for a steeper slope, but does not create it.....

I'l post back in a little while after creating some filters with much lower taps using your program.....

Btw, using filters based on the remez algorthim I get no ringing what so ever.... I have no 'mid speaker high frequency noise'...

[Theo404]

ok, tried 1024 tap filter, you are indeed correct that with your program fewer taps produce a shallower slope, but I then tried listening to these filters, they sound HORRIBLE..... just cant listen to them, (though the ringing almost disapeared).

So is there anyway to reduce the slope of the filters it produces while keeping tap count the same????

Thanks.

[KOON3876]

(1) Can you measure waveform and frequency spectrum of "ringing"?

(2) What is your FIR engine? my GPUFIR?

(3) You should modify CreateFres() function to get dull curve.
___|-----|___ -> ___/-----\___
But it will have no effect to signal quality.