[LAU] Re: How do I create a FIR-filter with opensource tools?

Thanks, Fons!

So, no quick and dirty solution but I expected sth like that. Will take 
some time to get through your advices.
Problem: I tried to get through the DRC-manuals some years ago and got 
lost configuring it. Just couldn't finish.

Let's see how far we get this time…

Greets!
Mitsch

Am 28.03.25 um 11:30 schrieb Fons Adriaensen:
> On Fri, Mar 28, 2025 at 12:47:06AM +0100, Michael Jarosch wrote:
>
>> Steps missing? Or am I totally wrong, here? What tools can I use?
> So you want both crossover and room correction filters.
> The first thing to do is to separate the two problems:
>
> 1. First implement the crossover processing.
> 2. Once you have that in place, measure the speakers and/or
>     room and implement the correction filters.
>
> One reason is that (1) will affect (2), the other is that
> combining the two from the start is more complicated and
> a sure recipe for errors.
>
> When you have both, it would be possible to combine the
> two into a single FIR filtering operation, but there is
> nothing gained by doing this and I would advise strongly
> against doing this.
>
> 1. For the crossover you can use zita-lrx wich will
> provide 2, 3 or 4 way Linkwitz-Riley filters along with
> configurable gain and delay for each band. Zita-lrx is
> a command line Jack application. Once you have the correct
> configuration file you can run it with a single command
> which will also to care of Jack connections.
>
>
> 2. For speaker/room correction the best open-source solution
> is DRC (Digital Room Correction) by Denis Sbragion.
> <https://drc-fir.sourceforge.net/>
> DRC uses some quite sophisticated methods to 'invert' the
> measured responses. Doing this correctly is not as simple
> as you may imagine. For example you will need frequency-
> dependent windowing - at low frequencies you can correct
> both the room and the speakers, while for higher frequencies
> only the 'direct' sound should be corrected. The DRC manual
> goes into a lot of detail to explain all of this and you'll
> need some time to absorb and understand all of it. But AFAIK
> this is the only tool that gets it right.
>
> To measure the speaker/room response you can use the tool
> provided by DRC, or e.g. Aliki, or zita-jacktools (more
> about that later).
>
> To do the actual filtering you can use jconvolver.
>
> 3. An alternative approach is to use zita-jacktools for
> everything. This is a collection of DSP processsors.
> Each of them is a Jack application and also a Python
> class (the actual DSP is of course all done in C++).
> It has both crossover filters and convolution processors,
> and a lot more.
>
> Using this you could create a simple Python script
> that combines all the processing. One advantage is
> that since everyhing is controlled by Python, you
> can easily add a GUI (using e.g. PyQt) or remote
> control.
>
> You could also use zita-jacktools to automate all
> the measurements, so you can repeat them easily.
>
> Just write if you need more help.
>
_______________________________________________
Linux-audio-user mailing list -- [email protected]
To unsubscribe send an email to [email protected]