Filterdetail, Plot, and Filtergraph

Sep 5, 2012 at 6:31pm

Filterdetail, Plot, and Filtergraph

The documentation on Plot/Filtergraph is confusing me, so I have a quick question: Is it possible to use a Filtergraph with multiple filters (or multiple filtergraphs’ list outputs, shoved together in one long list) into Filterdetail, and show this cascaded filter on a Plot object? If it is, I can’t seem to figure it out.

#64242
Sep 9, 2012 at 3:09pm

No – because, frustratingly, there is no easy object to turn biquad filter coefs into a list plot~ can plot. However, what i do is whenever i need to update the filter response curve in my plot~ from my filtergraph~, i query the gain of the filtergraph~ for each point i want to plot with, eg [uzi 512]‘s count output * (sample_rate/2/511), collect that into a list with [zl 512 group 512], and send that to an input of plot~. (don’t forget the 1st numerical argument of zl, otherwise your list will always be truncated to 256 members and you’ll be very confused)

#231644
Sep 9, 2012 at 3:26pm

That sounds a bit too intense for me – I have anywhere from 1 to 100 (or more) filtergraph~s hiding in poly~s that I’d have to query – would get really ugly, really fast. I guess I’ll just keep using another filtergraph~ for viewing the combined plots.

#231645
Nov 7, 2012 at 1:07pm

Hi i’ve been using Max MSP for about a year now, this is my first forum post – firstly I want to say how helpful this resource is – but i’m getting stuck on this also.

I want to overlay a visual of a filtergraph~ over a plot~ of the spectrum analysis – similar to the EQ in Presonus Studio One. I have tried to do this the easy way – setting the alpha of the Plot bg to 0 and placing it over the filtergraph – but I can’t get the thing to line up properly – ie setting grids at 10Hz 100Hz and 1000Hz are always offset – I’ve played around in the Inspector making the range of each match but they just wont line up… Any ideas?

Do I need to dump the output of the Filtergraph into the Plot and display it as a second graph? – this seems most logical – but i’m struggling to work it out.

Any advice would be most appreciated

Chris

#231646
Nov 8, 2012 at 4:40am

yeah – dump it. that’s what i do. Not the fastest thing in the world, but it works. Alternately you could use this info http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt to write a javascript or java object that calculates the frequency response of a filter from the coefs output by the filtergraph~ and outputs it as a list of points for plot~. This would be somewhat involved if you’re not an experienced programmer, but it can certainly be done.

#231647
Nov 8, 2012 at 8:49pm

Thats perfect, i’m testing it now and it will work fine for what i need, just needs a bit of tweaking. Humble thanks

#231648

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