Rasberry Pi Effects

guitarboy2828

I have been building some DIY pedals and learning lil bits of whatever I can in the process... I've been reading about DSPs and came across Raspberry Pi effects and was wondering if anyone else out there had thought about giving guitar effects via the Pi a go? Would the sound be too digital?

There are two videos showing what the Pi is capable of. Seems pretty cool. I reckon the second one could be boxed in a floor enclosure with some footswitches and pots. Could program presets and footswitches to cycle through the presets.

Would love to hear from a programmers point of view what they think about the code for something like this (as I know NOTHING of that sort).

Think it'd be an awesome project! ?

AlanRatcliffe

Nothing wrong with "digital sound" when it's done right - Lexicon, Strymon, most recordings in the last 20 years, etc..

Raspberry Pi and Arduino is great for making FX. But I think the real issue with any of these devices is they are only as good as the algorithms you use - you can dedicate a high end Sharc processor to a single effect and if you use a cruddy algorithm, your results will be cruddy.

=

guitarboy2828

Alan Ratcliffe wrote: Nothing wrong with "digital sound" when it's done right - Lexicon, Strymon, most recordings in the last 20 years, etc..

Raspberry Pi and Arduino is great for making FX. But I think the real issue with any of these devices is they are only as good as the algorithms you use - you can dedicate a high end Sharc processor to a single effect and if you use a cruddy algorithm, your results will be cruddy.

=

Ahhh, make sense. That video there sounds pretty decent to me. Seems pretty programmable too! Time to buy a Pi to play with! ?

peterleroux

The main stumbling block with the Pi is that it doesn't have analog in, so you'd need to sort out the audio input via USB (starts out cheap,but takes up one of the 2 USB ports available) or with a custom DSP chip like the new one from RS (not cheap). I'm busy building an infrared camera with one at the moment, a looper/reverb/delay stompbox is one the cards next (fever dream sketch below)

ryanguit

Hey guys. I also have a love/hate relationship with my pi. I have a great little puredata synth running that I want to use live with my guitar rig as randomness. I bought the wolfson board this morning from pifactory.co.za for R541.50 which was the cheapest by quite a bit and they had stock. ( ill collect to save on courier).

Problems with pi:
Sd card corruption as pedalboards aren't going to shutdown -h NOW for you. Solution I found is alot of hacking minimizing writes to sd card but not yet getting my hopes up.

And of course audio card doubles the cost price.

For me, its fun but DSP can be entered into for about the same cost with a development board and the product will be far more stable and marketable. I just like the idea of the pi more than the pi itself audiowise. Lastly the drivers for wolfson aren't even supported yet. More hacking! Yay

Sent from Tapatalk 2

guitarboy2828

peterleroux wrote: The main stumbling block with the Pi is that it doesn't have analog in, so you'd need to sort out the audio input via USB (starts out cheap,but takes up one of the 2 USB ports available) or with a custom DSP chip like the new one from RS (not cheap). I'm busy building an infrared camera with one at the moment, a looper/reverb/delay stompbox is one the cards next (fever dream sketch below)

Are you making a slightly more versitile one of these: http://www.instructables.com/id/Homebrew-Digital-Effects-Pedal/?ALLSTEPS

What chip are you using?

Infrared camera, 1080p? Would love to see some of your designs for that. Thermal and infrared camera's are super duper expensive. i work in video, so have looked into buying several times.

peterleroux

Paul E wrote: Infrared camera, 1080p? Would love to see some of your designs for that. Thermal and infrared camera's are super duper expensive. i work in video, so have looked into buying several times.

Not a thermal imager, unfortunately, just the Raspberry Picam NoIR- Near infrared only. The sensor is 5Mp and ships without any filters so you can add your own.

What's nice is it does 1080p at 25fps but can handle VGA at 90fps.

Here's a still:

guitarboy2828

peterleroux wrote:
Paul E wrote: Infrared camera, 1080p? Would love to see some of your designs for that. Thermal and infrared camera's are super duper expensive. i work in video, so have looked into buying several times.
Not a thermal imager, unfortunately, just the Raspberry Picam NoIR- Near infrared only. The sensor is 5Mp and ships without any filters so you can add your own.

What's nice is it does 1080p at 25fps but can handle VGA at 90fps.

Here's a still:

Oh wow, super cool! I had a Canon 7D converted to Infrared. Sent it off to London. It works super super well. We had some infrared spotlights and wide lights, so for night time it was amazing!

Attila

pedalSHIELD Arduino Guitar Pedal

http://www.open-electronics.org/guest_projects/pedalshield-arduino-guitar-pedal/

ryanguit

Ok I have it up and running with a latency that is all but non existent and, compared to the trouble i had last year using usb soundcards, a breeze to set up. The fact that a USB card can be as cheap as R35 and give a similar latency was pretty cool though.

Raspberry pi model B + Wolfson soundcard + SD = R1300.

soundcard has not yet got drivers built in kernel so had to Google a bit to find an image to start with.
Looks like it is more stable without the USB hoops (force 1.1 mode, disable ethernet, etc) i had to jump through for lower latency so i am loving it.

So if anyone is thinking of getting that wolfson card, remember you will be locked at the current kernel (if you update, you will have to complile your own kernel with the patches). Not a big deal for me, I just use this SD card for this application.

I'll be very surprised if latency is over 10ms. It is definitely quicker than my laptop with a R3000 soundcard running at "8ms" which is closer to 15ms roundtrip...

Ok summary:
-download Ragnars patched raspbian kernel or a full image from same thread: http://www.element14.com/community/message/107186?tstart=0#107186
-set up soundcard using usecase scripts (alsamixer has a hundred non coherent options, scripts are included and very simple)
-test using arecord and aplay.
-install pd-extended using apt-get, etc.
-build a patch and adjust audio settings etc.
-then call it with: pd-extended -alsa -nomidi -nogui -audiodev 0 patchname.pd

!Without "-nogui -audiodev 0", i get errors with memory allocation and if it pops up again i'll have to move to pd-vanilla which is apparently working without error on this wolfson card.

I have it running a patch with speaker and room emulation: guitar-pedalboard =THIS= headphones. would work as a looper easily.

peterleroux

Good news Ryan! What sort of patches have you got running on it? Puredata looks to be the most powerful option short of hand-coding, but also a bit of a headache on a headless machine

ryanguit

No headaches here. I used jack in the past but pd runs on the pi with alsa now alot better than it used to.

you need to drop a [loadbang]-[delay 1000]-[pd dsp 1] somewhere to wait a bit at patch startup before turning on audio dsp. Then headless works for me (using ssh or with nothing attached at all). My delay pedal (spin FV-1 based) uses an arduino to make it tap tempo, so now I am trying to decide on whether to go spi or Fudi to send data to the pi. pduino?

my patch is very simple, basically 10 filters, and about a 50tap delay ranging from 1ms-60ms (room) added a long delay for fun (built last night) I tried a 20 sec delay which it handled fine. But I dont use delay longer than 600ms nor a looper, so was just curiousity. You are welcome to send me a patch and ill check how it performs.

latency est rig is going to be:
mono audio file played stereo from PC.
left side through pi running a bypass patch
right side bypassed.
record stereo in PC

measure the latency between 2 peaks of a clap.

aja

Attila Barath wrote: pedalSHIELD Arduino Guitar Pedal

http://www.open-electronics.org/guest_projects/pedalshield-arduino-guitar-pedal/

+1 karma, that is pretty cool!