what if I made a little visual programming language for my synthesizer 🤔

[aeva@mastodon.gamedev.place]

I have all these big plans for using procgen to do wire management ( https://mastodon.gamedev.place/@aeva/114617952229916105 ) that I still intend on implementing eventually, but I'm finding their absence unexpectedly charming at the moment

[aeva@mastodon.gamedev.place]

anyone up for some doof and boop music #mollytime

[aeva@mastodon.gamedev.place]

a good test to see if your speakers can emit 55 hz or not

[aeva@mastodon.gamedev.place]

I whipped up a version of the doof-and-boop patch that automates the alternating connections with a pile of flip flops and I've been grooving out to it for the last two hours 😎

[aeva@mastodon.gamedev.place]

I tried doing a live jam for some friends tonight where I had the drum machine patch going along with a simple synth voice on top of that which I intended to drive with the midi touch screen keyboard I made back in January, but I quickly found that to be unplayable due to latency in the system. I'm not sure exactly where as I haven't attempted to measure yet.

[aeva@mastodon.gamedev.place]

I figure if I move the touch screen keyboard into the synth and cut out the trip through the midi subsystem that might make the situation a little better (again, depending on where the real problem is)

Anyways, it got me thinking, I think processing input events synchronously with rendering might be a mistake, and it would be better if I could process input events on the thread where I'm generating the audio.

[aeva@mastodon.gamedev.place]

I added an instruction called "boop" that implements a momentary switch, and built a small piano out of it, and also built a metronome in the patch. That is very playable, so the latency must have been something to do with having one program implement the midi controller and the other implement the synth. I think I had this same problem with timidity a while back, so maybe it's just linux not being designed for this sort of thing.

[aeva@mastodon.gamedev.place]

with one program being the midi controller and the synthesizer it's pretty playable, but sometimes touch events seem to get dropped or delayed. that is probably my fault though, there's a lot of quick and dirty python code in that path, though I'm not sure why it's only occasional hitches

[aeva@mastodon.gamedev.place]

k, I've got tracy partially hooked up to mollytime (my synthesizer), and with mollytime running stand-alone playing the drum machine patch (low-ish program complexity), the audio thread (which repeatedly evaluates the patch directly when buffering), the audio thread wakes up every 3 milliseconds, and the repeated patch invocations take about ~0.5 milliseconds to run, with most patch evals taking about 3 microseconds each.

[aeva@mastodon.gamedev.place]

almost a third of each patch invocation is asking the also if there's any new midi events despite there being no midi devices connected to mollytime, but that's a smidge under a microsecond of time wasted per eval, and it's not yet adding up enough for me to care so whatever

[aeva@mastodon.gamedev.place]

anyways, everything so far is pointing toward the problem being in the UI frontend I wrote, which is great, because that can be solved by simply writing better code probably unless the problem is like a pygame limitation or something

[aeva@mastodon.gamedev.place]

I switched pygame from initializing everything by default like they recommend to just initializing the two modules I actually need (display and font) and the audio thread time dropped, probably because now it's not contending with the unused pulse audio worker thread pygame spun up. The typical patch sample eval is about 1.5 microseconds now, and a full batch is now under a millisecond.

[aeva@mastodon.gamedev.place]

tracy is a good tool for profiling C++, but the python and C support feels completely unserious :/

[aeva@mastodon.gamedev.place]

making building with cmake a requirement to use the python bindings and then only providing vague instructions for how to do so is an odd choice.

[aeva@mastodon.gamedev.place]

using cmake is a bridge too far, so I figure I'll just mimic what the bindings do, but it turns out they're a bit over engineered as they're meant to adapt C++ RAII semantics to python decorators and I don't want to pay for the overhead for that when I could just have a begin and end function call to bind instead. that probably will have to be wrapping new and delete like they do though because there is no straight forward C call for this.

[aeva@mastodon.gamedev.place]

The relevant C APIs are provided as a pile of macros that declare static variables that track the context information for the begin and end regions. This seems to be on the theory that you would never ever ever want to wrap these in a function for the sake of letting another language use them in a general purpose way. The inner functions they call are all prefixed with three underscores, which is basically the programmer way of saying "trespassers will be shot without hesitation or question"

[aeva@mastodon.gamedev.place]

also there's this cute note in the docs saying that if use the C API it'll enable some kind of expensive validation step unless you go out of your way to disable it, which you shouldn't do but here's how 🙄

[aeva@mastodon.gamedev.place]

C++ RAII semantics are so universally applicable to all programs (sarcasm) that even the C++ standard library provides alternatives to scope guard objects if you don't want to use them. come on man

[aeva@mastodon.gamedev.place]

tragic. pygame.display.flip seems to always imply a vsync stall if you aren't using it to create an opengl context, and so solving the input events merging problem is going to be a pain in the ass. it is, however, an ass pain for another night: it is now time to "donkey kong"

EDIT: pygame.display.flip does not imply vsync! I just messed up my throttling logic :D huzzah!