Raspberry Pi - Current Status?

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cpsmusic
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Raspberry Pi - Current Status?

Postby cpsmusic » Tue Oct 13, 2015 12:35 am

Hi Folks,

I'm a guitarist and music producer, and I've also worked in computer programming.

I'm currently developing some real-time guitar effects using Csound. I notice that there have been some attempts to use the Raspberry Pi for real-time effects processing and thought that it might be a good final platform for studio work, but that it has some problems due to latency and also that the built-in audio is only 11-bit.

Just wondering if that is still the case?

Also, I've come across a couple of dedicated audio I/O boards (Wolfson, Cirrus Logic) but they don't mention latency. Does anyone know if theses are any better?

Finally, why can't the audio latency be reduced - is it a hardware issue or OS/software issue?

Cheers,

Chris

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English Guy
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Re: Raspberry Pi - Current Status?

Postby English Guy » Tue Oct 13, 2015 7:46 pm

I would like to know that as well. This looks like it may be of interest:

https://www.hifiberry.com/dacplus/

or even

https://www.adafruit.com/products/1761

asbak
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Re: Raspberry Pi - Current Status?

Postby asbak » Wed Oct 14, 2015 8:15 am

Just out of curiosity, would a Behringer UCA202 USB audio interface + DI, or something similar like the UCG102, be capable of low latency audio on a Rasp-Pi? Because if yes, these are pretty cheap and reasonably usable quality audio interfaces.

I imagine latency problems are resolvable, more info in the autostatic urls.

Some more info on it here.
http://wiki.linuxaudio.org/wiki/raspberrypi
http://autostatic.com/2015/04/18/raspbe ... revisited/
http://autostatic.com/2015/09/13/buildi ... pberry-pi/

Broomy
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Re: Raspberry Pi - Current Status?

Postby Broomy » Wed Oct 14, 2015 9:23 am

Interesting thread and welcome to the forum Chris.

From what I know you'll need some kind usb soundcard to convert your signal, then you have to get your device running with some kind of os, Debian is commonly used. You've probably already checked this article.
Have you considered / checked Guitarix, that might be of interest to you?
on real time guitar effect on RPi

Hans
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- Popularizing an all fifths tuning for guitarlike instruments
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autostatic
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Re: Raspberry Pi - Current Status?

Postby autostatic » Mon Oct 26, 2015 1:58 pm

Hello Chris,
cpsmusic wrote:I'm a guitarist and music producer, and I've also worked in computer programming.

I'm currently developing some real-time guitar effects using Csound. I notice that there have been some attempts to use the Raspberry Pi for real-time effects processing and thought that it might be a good final platform for studio work, but that it has some problems due to latency and also that the built-in audio is only 11-bit.

Just wondering if that is still the case?
Yes it is.
cpsmusic wrote:Also, I've come across a couple of dedicated audio I/O boards (Wolfson, Cirrus Logic) but they don't mention latency. Does anyone know if theses are any better?
USB audio interfaces add one period of latency and the Cirrus and Wolfson cards don't show this behavior. So in that regard the dedicated audio boards perform better. CPU-wise there's not much difference so you'll hit about the same limits with either USB or dedicated boards. The dedicated audio boards are harder to set up though, most USB devices are plug and play. USB audio does suffer from the poor USB implementation of the RPi, it takes quite some tweaking to get it to run at lower latencies. USB is much cheaper though, you can get decent PCM2704 based interfaces for like under $10.
cpsmusic wrote:Finally, why can't the audio latency be reduced - is it a hardware issue or OS/software issue?
Hardware. Both I2C (dedicated audio devices) and USB consume precious CPU cycles on the Rapsberry Pi. For USB add the poor USB implementation. Really, the RPi isn't made for low latency audio but you can get a long way. You might want to check my personal experiences and findings on my blog at https://autostatic.com/

Jeremy

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autostatic
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Re: Raspberry Pi - Current Status?

Postby autostatic » Mon Oct 26, 2015 2:03 pm

asbak wrote:Just out of curiosity, would a Behringer UCA202 USB audio interface + DI, or something similar like the UCG102, be capable of low latency audio on a Rasp-Pi? Because if yes, these are pretty cheap and reasonably usable quality audio interfaces.
Yes you can achieve lower latencies with those devices. I've got a UCG102 myself and tested it succesfully with the RPi.

Jeremy

asbak
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Re: Raspberry Pi - Current Status?

Postby asbak » Mon Oct 26, 2015 3:59 pm

Many thanks for this information!


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