Jamulus on Raspberry Pi pico

[frenrude]

Hi everyone.
We are three or four people in one room, some with an instrument and singing, rehearsing online with several other such groups. We use up to 4 instances of Jamulus, struggling with the different chat windows and all the wiring.
The idea is to use one Linux computer in GUI mode for one player and shared output, and just "jamulusified microphones" for the others.
A raspberry pi Zero has already been demonstrated by Volker Fischer to be capable of running Jamulus. My idea is, can we go even cheaper and smaller with 5$ Raspberry Pi Pico carrying a MEMS microphone and running a headless version of Jamulus stripped down to the bare absolute minimum necessary to emit a microphone channel ?
Somewhere I read that the Pico can run embedded Linux, but will the 2x150MHz be sufficient for opus compression ?
Or is this idea completely in the clouds ?
Thank you in advance for any helpful hint or hand :-)

[mcfnord]

I bet you'd run into RAM limitations on Pico first. I've been putting small graphics apps on the Pico and the Zero. The difference is pretty huge. I can't show color images on my little OLED yet because Pico runs out of RAM loading the image. That's why I speculate that RAM will not be adequate.

[frenrude]

Hi mcfnord, thank you for your reply.
I agree with you that even the 512KB of a pico2 is not very much Ram.
But what is it needed for: mainly the Linux kernel and jack and all that supporting stuff, or for jamulus' core functionality of collecting, compressing and transmitting a mono audio stream at 48kHz ?
Maybe a veeeerrrrry basic version of jamulus could be distilled that runs without Linux, Jack and without anything that is not strictly necessary for the task ?
It seems to me that for a pure microphone function no jitter buffer would be required.
I see the biggest challenge in the opus codec (of which we would need only the encoder part), but I have no clue what it actually does with the samples and how much this could be reduced.

[dcorson-ticino-com]

If programming time costs nothing and you have several experienced programmers who have nothing else to do I guess this could be possible.
If, however, your programmers need to eat once in a while I think that paying the maybe 15 chf difference in price for the more expensive hardware will pay for itself very quickly.
This would not be a project for a couple of evenings by rainy weather.

[ann0see]

If someone would want to start development for this, the headless build would be a great start.
The team will probably not work on this, but we're open for PRs.
Personally, I'd go with the Pi zero - for 15 €, it should be affordable enough.

[ann0see]

Alternative idea: Use a mixer and connect it to an old computer. You can probably get an old one of ebay or ask around.

[frenrude]

Dear all, thank you for your valuable replies.
I'll follow your advice and abandon the project of jamulus on Pico for now. Maybe with a next generation it will be easier.

I'll probably go for used netbooks and find or create some analog circuitry to produce a cheap DIY microphone to use with the internal sound card for each. Yes I know, latency will be worse than with an usb audio interface. But we need to be as cheap as possible for the musicians to agree.