Software EQ

[zreyz]

hey,

I have been given an assignment to code a equalizer.

input is pcm data,

 

ihave no clue how to go about, can anyone give me any heads...

[paulears]

Hi, welcome to the BR. I'm not sure we can help. We are mostly users, although a few of our members are into software design. That said, we have never to my knowledge had this kind of request before, and our normal rules exclude computer forum style discussion as most of us are into production in the theatre and events industries - or are students hoping to work in this area.

 

I'll leave the topic open for a while, but I doubt many people will be able to contribute. As a college assignment, I would have assumed that your teachers would have laid down the basic processes, or are they expecting you to do the research? If you don't have a clue, I for one still think you may still know more about this subject than many of us!

 

Fingers crossed.

 

Paul

Mods

 

 

 

(Many of us find converting to binary hard enough!)

[zreyz]

I'll leave the topic open for a while, but I doubt many people will be able to contribute. As a college assignment, I would have assumed that your teachers would have laid down the basic processes, or are they expecting you to do the research? If you don't have a clue, I for one still think you may still know more about this subject than many of us!

 

 

thanks a lot, but the entire research is left to me, can you link me to anyone who is in the development area??

would be obliged....

[j_b]

This book should teach you pretty much everything.

 

http://www.dspguide.com/

 

It's free online too. If you don't think that it helps you, and still leaves you some gaps in understanding, then I think you need a different project!

 

 

This is a big project for someone who doesn't know where to start.

 

Here's a hint though. You say 'code an equiliser'. You don't say graphic equaliser, so remember an EQ can be as simple as a HF knob and an LF knob on cheap mixers. That brings you down to maybe 2 sides of paper of maths.

http://images-eu.amazon.com/images/P/0966017633.01.MZZZZZZZ.jpg http://images-eu.amazon.com/images/P/075067444X.01.MZZZZZZZ.jpg

[jamesperrett]

The DSP Guide is an excellent place to start. If you have access to Matlab then take a look at the signal processing toolbox which will allow you to try out all sorts of different filters.

 

Cheers

 

James.

[Dmills]

Just a couple of minor points:

 

For IIR filters (particularly at low frequency and high Q), a 32 bit float does not have sufficient word length to reliably give a numerically stable filter (you will want to use doubles).

If you are implementing on a Pentium IV, be wary of denormals in the feedback loop, they really hurt performance.

Writing an IIR filter that can be adjusted while in use is tricky as you can very easily end up with weird noises while tweaking it.

Are you doing a graphic or a parametric?

 

Keywords: Z transform, recurrence relation, S plane, Z plane, Pole/Zero, Biquad.

 

Finally, go and raid the sourcecode repositories for ideas, your collage will spot a direct copy, but for ideas and general structure hitting plugin.org.uk or the sourceforge, CMT collections is probably legit (provided you give a cite).

 

Regards, Dan.

[Simon Lewis]

My colleague wrote this http://images-eu.amazon.com/images/P/0201398516.01.MZZZZZZZ.jpg, and if I remember correctly it has some worked examples and templates to get you started.

 

Moderation: Amazon tags added to this and other posts

[dbuckley]

And when you've finished with Mr Smiths digital filter book (which is really good, even an innumerate lout like me gets some of it) try his other book, link here.

 

(By the way, although freely downloadable, I recommend hardcopy! your printer will thank you)

http://images-eu.amazon.com/images/P/0966017617.01.MZZZZZZZ.jpg

[Brian]

Moderation: BBM time I'm afraid. This topic has nothing to do with backstage and everything to do with college assignments . With answers delivered (thanks guys) this topic is now closed.