provide low level event filtering?

[HansHermann123]

Hi,
I am using this on a pretty old laptop. Unfortunately my E-Piano sends loads of realtime clock (F8) and active sensing (FE) events all the time, which I can't turn off. This bombardment with events causes quite some CPU load, even while all non Note events are ignored by my script. Is there a possibility to filter events by type at a very early stage, so only minimum processing is done before they are dismissed and thus they don't cause significant CPU load?
Cheers!

[jazz-soft]

Sounds like a good idea...
Are you talking about Node.js or browser runs?

[HansHermann123]

It's running in Firefox atm. I'm not familiar with nodejs, as I understand it's more complicated to get graphical applications running in it? Actually all my graphics output comes from three.js, no additionally HTML, so maybe porting it to nodejs is an option, too.

[jazz-soft]

There are many reasons that may cause high CPU load, that also includes three.js.
Can you share your code?

[HansHermann123]

This is the application WIP:
https://www.thorsten-schepers.de/3dpiano/
I already did a whole lot to bring down three.js CPU load to a minimum. I started from this https://github.com/reality3d/3d-piano-player which nailed my old CPU to 100% load constantly. I reduced the scene complexity significantly and limited frame rate to 10 fps max. All in all I managed to bring down CPU usage to now 15% on my old laptop. Now I can clearly see, the moment I plug in my epiano, CPU goes to 40%. If I plugin another USB piano which does not send clock events, CPU stays at 15%. Playing a few chords doesn't raise CPU load above 20%. So the high load is clearly caused by the event load.
(BTW 40% is not okay for me because I need to run several other apps in parallel which also need considerable CPU, so I'm trying to get it down).

[jazz-soft]

As an experiment, you can disable MIDI In and play from a MIDI file instead. Will it improve the performance?
Just connect your midi_in_evt function to the output of the MIDI player (see https://github.com/jazz-soft/JZZ-midi-SMF)

[HansHermann123]

I didn't test midi file player yet, but I found sort of a "fix".
The frequency of midi clock events depends on the tempo, so if I set tempo to the lowest possible value (32 instead of 120 default) I get the CPU load down to an acceptable level.
BTW the code from which I started (see GitHub link above) had a midi file player implemented (different implementation though), that one also caused a relatively high CPU load even when just sitting there and not actually playing a file.

[jazz-soft]

Please try it with a MIDI file for a clean experiment...
Another question: do you ignore the clock/active-sensing messages or you forward them to the output?