i noticed that the CPU toll on BELA is quite high with puredata and fexpr~
If you are not going full-polyphonic, you could try to disable unused [fexpr~]
objects based on the envelope's amplitude, either via [switch~] or using
[start( and [stop( messages to [fexpr~].
maybe (if i take this further) i have to try and implement this in C directly
(or as a pd external) to make it more cpu friendly.
I concur this would be the best way to optimise CPU performance and it
shouldn't be too hard. Let me know if you need help.
Best,
Giulio
Simon Iten wrote on 14/03/2023 03:25:
thanks again for this, these explanations make it much clearer.
yes i also thought that one pll per string might be the ticket.
i noticed that the CPU toll on BELA is quite high with puredata and fexpr~
maybe (if i take this further) i have to try and implement this in C directly
(or as a pd external) to make it more cpu friendly.
a sync osc would be a great external i think.
it is actually only 5 strings on my bass, so more of a pentaphonic pickup :) my
bad..
the term hexaphonic is used among guitarists/bassists to describe a
split-string pickup interchangeably.
my bass is standard 5 string tuning:
B: 30.87 HZ
E: 41.2
A: 55
D: 73.4
G: 97.99
every string has a two octave range.
i did a version of my “gr300” ish guitar to sawtooth converter in puredata with
building blocks and it works but your pll is less prone to octave jumping
somehow even with the same input filtering applied…
On 13 Mar 2023, at 22:01, Charles Z Henry <[email protected]> wrote:
On Mon, Mar 13, 2023 at 8:32 AM Charles Z Henry <[email protected]> wrote:
On Mon, Mar 13, 2023 at 7:41 AM Simon Iten <[email protected]> wrote:
i do not currently grasp the math in the fexpr~ objects, but will try to get
into it…
It's a simple kind of dynamical system. It responds based on its
inputs but also its internal state when receiving inputs. That's why
[fexpr~] works well for this. You can add additional expressions and
reference them from each other. There can be internal hidden state
variables, etc....
Right now, I just left the outlets all hanging out of synch_osc~ for
debugging. Connect up some plots (maybe longer block sizes would be
better) to see what's in the
I'd say it's actually the *simplest* kind of dynamical system for
phase locking (and a very artificial one). It's just a discretized,
noise-less little phasor. e.g.
[fexpr~ modf($y1+1.0/44100)]
is just a phasor that counts from 0 up to 1 over 44100 samples
So, if I want, I'll change that to use [samplerate~] and pass in
1/samplerate as a float $f2
[fexpr~ modf($y1+$f2)]
Now, add frequency in $y2, and multiply
[fexpr~ modf($y1+$y2*$f2);
80]
It's a 80 Hz phasor.
Next, I extend the phase that's stored in $y1 so it accumulates over
time between impulses from $x1 in $y3
[fexpr~ modf($y1+$y2*$f2);
80;
if($x1==1, $y1, $y3+$y2*$f2])
So, now I have phase and freq as functions of time, and I'll add in
some updates to the terms and put them in $y4, $y5 so that the updates
get added in when receiving an impulse from $x1
[fexpr~ modf($y1+$y2*$f2+$y4*$x1);
80 + $y5*$x1;
if($x1==1, $y1, $y3+$y2*$f2]);
($y4) phase update function of $y3;
($y5) freq update function of $y3 ]
With some re-ordering of things and adding in parameters and scaling
coefficients with $f inlets, that's basically what's in synch_osc~
right now
The choice of the phase and frequency update functions is what causes
the synchronization.
For anyone who's interested in some light reading (LOL), I noticed
Izhikevich has put "Dynamical Systems in Neuroscience" (~500 pgs) in
pdf at https://www.izhikevich.org/publications/
Chapter 10 is on synchronization and it has a section on
phase-locking. It took me over a year to read this, much of the math
eludes me also
I want to make a version that's good for your hexaphonic pickup, you
know that just works well as a sensor and has clean output.
synch_osc~.pd has problems with low frequencies and I know where that
comes from
I think it has to be 6 PLL's, each tuned to the range of each string.
Can you tell me what the range is on your instrument?
Best,
Chuck
_______________________________________________
[email protected] mailing list
UNSUBSCRIBE and account-management ->
https://lists.puredata.info/listinfo/pd-list
_______________________________________________
[email protected] mailing list
UNSUBSCRIBE and account-management ->
https://lists.puredata.info/listinfo/pd-list
