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A low latency guitar effects processor suitable for running on a Raspberry Pi

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Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#101

Post by riceart »

H1Supreme wrote: post #88
woudsma wrote: post #7

Very cool, I've ordered a Raspberry Pi touchscreen this weekend and it should arrive today. I want to make a MIDI sequencer with it, or at least play with the idea. I hope my old Raspberry Pi can work with MIDI (over USB) without too much latency..

Depends on how you want to utilize it. If you want to connect it to a computer as a MIDI device, you'll have to use an Rpi4 or one of the Pi Zero's. The Pi's The RtMidi library is probably your best bet for getting started. I found the ALSA library to suit my workflow a bit better, but the setup is pretty obtuse. RtMidi is much more user friendly in that regard. Also, look into implementing the Ableton Link library.…

Can you readily get an rpi4 anywhere?

The Odroid C4 you can actually get is an alternative with 4 USB ports and an OTG that is gadget capable. Unlike older models, mainline Linux support is decent.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#102

Post by mattkrause »

worik wrote: post #45
mr_sturd wrote: post #39

Earlier quoted context omitted.

Don't go leaving it exposed if you connect it up to the venue's WiFi, if you're playing live. ;)

Don't run wifi and real-time software at the same time.

Using wifi to trigger real-time software is often a bad idea, but using it to configure responses to future triggers isn’t necessarily so bad.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#103

Post by zamnos »

worik wrote: post #100
zamnos wrote: post #54

Earlier quoted context omitted.

What wireless technology would you recommend instead then?

none, of course

Lol ok. Meanwhile the rest of the industry is moving on. I mean, how do you even do an wired connection to a drone? A lot of times guitarists will perform on a stage and the clients wants aerial views without the cost of a crane. Do you just tell them you can't do it and have them go with a different company?

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#104

Post by bob1029 »

bluGill wrote: post #73
bob1029 wrote: post #69

Earlier quoted context omitted.

Modern CPUs are surprisingly good at low-latency video as well. SIMD on something like a Zen4 core is a really big deal if used properly. I've got some prototypes in C# that can draw a 1080p bitmap and encode to JPEG in under 10ms. Using single threading, socket mux servers and aggressive multimedia timers means my network delay is usually right at 1ms. I feel like if you are just worried about audio, there is defini…

While video needs more CPU power, it can tolerate higher latency than sound.

Fair point. Audio also has a tendency to require more serialized throughput in complex signal chains. Video is more trivial to chunk out and process in parallel.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#105

Post by chestervonwinch »

razerbeans wrote: post #91

As others have mentioned, I think the interesting thing here would be understanding the latency for processing the signal. Anything in the single digit milliseconds would be fantastic! I know at one point I was looking into Raspberry Pi and ended up on Pedal Pi[0], though I couldn't get the parts I needed to make it work. I ended up using Teensy[1] and related audio shields[2] to get things working from a sound/accep…

Also, the teensy audio library is great!

https://www.pjrc.com/teensy/td_libs_Audio.html

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#106

Post by km3r »

ghostly_s wrote: post #92

Sweet, was just looking for something like this the other day. My use-case is not for guitar, but just to offload some fx processing out of a DAW - a friend and I have gotten into jamming recently, and while you can do just about any musical production task these days with a budget laptop and enough patience, where you quickly run into limitations is running multiple realtime effects. I'm not yet serious enough about…

I was thinking about something similar but wondering if you could do it over Ethernet and the VST API with low enough latency to be useful for a DAW. Or if you can figure out a way to make latency less of an issue all together and enable remote VSTs.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#107

Post by pdntspa »

zamnos wrote: post #103
worik wrote: post #100

Earlier quoted context omitted.

none, of course

Lol ok. Meanwhile the rest of the industry is moving on. I mean, how do you even do an wired connection to a drone? A lot of times guitarists will perform on a stage and the clients wants aerial views without the cost of a crane. Do you just tell them you can't do it and have them go with a different company?

With special nonstandard proprietary wireless protocols is the answer you're looking for. The same shit wireless stage mics use. Or control over cellular data. I can guarantee you they aren't pairing them to a 802.11 router. Lol ok.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#108

Post by kimburgess »

digitallyfree wrote: post #42
huehehue wrote: post #23

Earlier quoted context omitted.

Not exactly what you're describing, but I've been running my band directly into Logic Pro on an M1 (both for recording, and live shows). Dry signals go through amp sims and effects processors, and then route to both a FOH mix and an in-ear mix all on the laptop. Wish I had seen the OP's project months ago, but one bonus of the setup I describe is the ability to swap effects after the fact (by virtue of having the dry…

I've done live mixing with a laptop, DAW, and interface in the past and it does work but it's not something I would be comfortable with for an important show. Even with something like SAC (which is specifically designed for the task) the chance of hangs, crashes, etc. go up as at the end of the day it's just a program running on top of your OS. The setup and config also gets a bit hacky and you'll be the only one abl…

It's interesting you mentioned QSC. They're one of the few vendors in the installed audio space that have made the jump to COTS hardware: https://www.qsc.com/resource-files/productresources/dn/dsp_c....

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#109

Post by kimburgess »

bluGill wrote: post #73
bob1029 wrote: post #69

Earlier quoted context omitted.

Modern CPUs are surprisingly good at low-latency video as well. SIMD on something like a Zen4 core is a really big deal if used properly. I've got some prototypes in C# that can draw a 1080p bitmap and encode to JPEG in under 10ms. Using single threading, socket mux servers and aggressive multimedia timers means my network delay is usually right at 1ms. I feel like if you are just worried about audio, there is defini…

While video needs more CPU power, it can tolerate higher latency than sound.

Spot on. For context: 60fps gives you ~17ms of wiggle room before you start dropping/delaying frames. With 96kHz audio you have 0.01ms between samples. Drift above 0.05ms and you'll start introducing time domain issues in the human hearing range.

In other words, 'realtime' audio processing needs to happen 1700x faster that 'realtime' image work. Bandwidth isn't limiting factor, deterministic and uniform latency is that challenge for any signal as the sample rate goes up.

Re: A low latency guitar effects processor suitable for running on a Raspberry Pi

#110

Post by qotgalaxy »

bjelkeman-again wrote: post #78
vondur wrote: post #37

Earlier quoted context omitted.

I think the hip new guitar effects/sim is the Quad Cortex from Neural DSP. I've seen Kiko from Megadeth uses it for his live shows.

I think the AxeFx has more virtual knobs, but the QC is easier to use, and has Kemper-like sound capture tech.

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