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Related: Raspberry Pi 3 audio input?

I need to be able to input several jack microphones (minimum 2, more could prove useful) to my raspberry, to do some audio processing (between all inputs), and output to a speaker. To make things worse, I also require a low processing latency between microphones and speaker (2ms would be good, and ~6ms is too much).

I've found a list of possible expansion boards that would allow me to do this: https://elinux.org/index.php?title=RPi_Expansion_Boards#Sound Specifically the audio injector stereo sound card seems to have 2 inputs, and the audio injector octo sound card has more than enough. I can't find the documentation for any of these cards on how much latency they may have, however.

The other sound cards on the list seem to have only 1 audio input.

I'd like to know if there are any other expansion cards (for the PI 3B+) or the latency of the cards I mentioned.

Edit: some extra info from "Is Raspberry PI 2 B suitable for a real-time audio effects application?" mentions operating system has a big impact on this delay. If so- are there any OSes that are better for this purpose, or would it be better to do kernel coding as that thread suggests? (and is it accesible/easy to do so)

Edit: after some more research, a better option seems to be beaglebone with a "bela" extension on top, as it has a custom operating system that allows for the sound to be processed separately, thus reducing latency.

  • Please note that answers (though in this case that answer seems to be "not with the Pi...") should preferably be posted as answers not edited into the question. – Ghanima Jun 10 at 22:04
  • @Ghanima alright, I'll do that. Indeed, sadly it seems that the raspberry does not have a specialized audio shield for extremely low-latency programs! I wish it was not the case, as it would've been a lot cheaper :) – ZeroZ30o Jun 10 at 22:08
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I can confirm, after having used the Bela shield on top of a Beaglebone Black, that its latency is extremely low (<1ms) and quite capable of doing calculations on audio.

The normal shield has 2 jack microphone inputs and 1 jack stereo output. Strictly speaking, you have to buy the version that comes with jack adapters, though.

I do believe more inputs/outputs can be had with the analog pins, but I don't require them. They do however, provide another cape that does just that.

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