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Re: my small linear interpolator

Posted: Thu May 23, 2013 12:04 am
by RJHollins
Thanks for citing an example 'tester' !

Gives me something to hang on to as I follow along ... and definitely a useful programming concept.

Thanks!

Re: my small linear interpolator

Posted: Thu May 23, 2013 12:08 am
by tester
You're welcome.

The size of that X,Y table is not limited. By making it denser (more points) - you get more accurate curve, but I guess at greater arrays - it will start to work slower (may be of importance if using multiple at once).

It would be interesting to compare various (as many as possible?) interpolation approaches.

Re: my small linear interpolator

Posted: Thu May 23, 2013 8:38 am
by Drnkhobo
Thanks tester ;)

Its quite awesome actually! I suppose its like a function then, which can be used for calculating/deploying volume loudness curves?

Re: my small linear interpolator

Posted: Thu May 23, 2013 9:35 am
by tester
Yes. But you can also track other parameters this way.

Regarding loudness curves, there are two additional topics:
viewtopic.php?f=2&t=1373
http://synthmaker.co.uk/forum/viewtopic ... 12&t=12071

I created this one, because I wanted to understand what actually I'm looking for, and how it should work. I needed to "mess from scratch" so to speak.

Re: my small linear interpolator

Posted: Sun May 26, 2013 3:28 pm
by acg2010
@tester

While I have not have the chance to check out your schematic, your project sounded interesting and might help me in my project. I am working on a guitar cabinet sim. My first idea was to obtain readily and freely available on the internet (guitar forums, cab manuafacturers, etc.) frequency response curves of actual guitar cabs, then digitize that graph to obtain x (frequency) and y (db) values. These would be used either in an array or used to generate a transfer function that would modulate the volume depending on the frequency. Your interpolator work seems to fit well with the array approach. Of course this is just a simplistic approach as it would not create any phase distortion/shift that a real guitar cab might.

Does my approach make sense? Would just modulating volume or db of the input signal according to the frequency accomplish what I am trying to do?

Re: my small linear interpolator

Posted: Sun May 26, 2013 8:51 pm
by tester
I know that I may look like a guru, but unfortunately I am not one yet. ;-)
But let me clarify what (I think) this module can, and what can't.

1. You can automatically have different scalings for one input value.
(you can obtain input freq from pitch tracking elements)

2. You can assign different correction curves, depending on secondary input parameter
(like fundamental gain ranges, or some gain-to-gain rations, or else)

3. It will not work directly for live compensating FFT spectra of an input signal.
(consider FFT spectra as multiple input values at once).
For this one - you would require some sort of a filter?

My design here is rather simple. You probably rather will need filters, that will add a curve to FFT spectra - live.

Re: my small linear interpolator

Posted: Sat Jun 15, 2013 1:08 am
by tester
Following the idea - how to make it in streamed version, to pass blue wires through?

Re: my small linear interpolator

Posted: Mon Jun 24, 2013 1:56 pm
by tester
Is it possible to make stream version of such type of interpolator/follower?

Two options are in the game I guess: external array of correction values (would be great) or internal list (fixed).