[PD] UDOO Quad and Generic Guitar to USB link issues

Sun Apr 27 11:51:08 CEST 2014

do you use the hardware or the plugin tab in the pd preferences? i found that i had to use the plugin and not the hardware to get results without distortion. also you should use debian hard float image and not linaro, it works better with puredata. and, i would not use jack but alsa directly with puredata.

On 11 Apr 2014, at 01:54, Carlos Sanchez <csanchez126 at gmail.com> wrote:

> Neat project sir!
> 
> I have tried what you mentioned Brian and I cant get the system to even play sounds with the right device. Using aplay file.wav works with the default output but when i try to specify the output like so "aplay -D hwplug;2,0 file.wav" nothing comes up. I got these commands somewhere on the net, can you vouch for them? Also, when listing the devices with alsamixer, my soundcard lists a mic input which is odd since it has a mono in and stereo out...
> 
> If this is of any use, here is the output of aplay -l:
> 
> **** List of PLAYBACK Hardware Devices ****
> card 0: vt1613audio [vt1613-audio], device 0: HiFi vt1613-0 []
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> card 1: imxhdmisoc [imx-hdmi-soc], device 0: IMX HDMI TX mxc-hdmi-soc-0 []
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> card 2: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> 
> My soundcard is the card 2 and I can not get any sound out of it via aplay!
> 
> 
> 
> On Tue, Apr 8, 2014 at 5:26 PM, Brian Fay <ovaltinevortex at gmail.com> wrote:
> The reason I suggested trying "arecord | aplay" is because it would be running input and output simultaneously. In Audacity, you're doing one after the other.
> 
> Unfortunately, I'm not sure exactly what is going wrong here. Does your soundcard work as expected on other computers? Was it fine on the BeagleBone Black?
> 
> On the Raspberry Pi, I'm running a multi-effects pedal, all built in Pd. There's two parallel chains of processes, (each can run up to eight effects). The effects I'm using are a looper, delay, waveshaper distortion, flanger, granular synthesis (sort of limited implementation), reverb, and EQ. I'm controlling things with a QuNeo MIDI controller and a push button attached to the GPIO pins on the Pi.
> 
> By default, each of the eight effects in each chain are set to "bypass," which simply passes the signal onto the next effect. However, you can adjust this on the fly for the effects to be whatever you want, so I can set up something like:
> Chain A: looper -> distortion -> flanger -> delay -> granular -> reverb -> EQ -> bypass -> output
> Chain B: delay -> bypass -> bypass -> bypass -> bypass -> bypass -> bypass -> bypass -> output
> 
> I can independently control volume of each chain, so I could use Chain A to build up some sort of droning ambience, and then solo over it using Chain B.
> 
> In practice, there is definitely a limit to the ability of the Raspberry Pi. I think the example I just mentioned would probably run, but if I try throwing too many effects on at once, (flanger, reverb, distortion, and granular are all pretty intensive), I will start getting glitches - huge crackles and jitters in audio. Turning off a few effects will stop the glitches, but I all I can do to prevent them is to be conservative about how many effects I turn on.
> 
> Just uploaded a little demo to Soundcloud of a recording I made with a somewhat similar FX setup to what I mentioned. It was recorded with my cell-phone, so it's a bit awful sound quality-wise (also really really quiet, whoops...).
> https://soundcloud.com/ovaltine-vortex/raspberry-improv
> 
> If you're curious about the patches and stuff, it's all here, but it's hard-coded to MIDI values on the QuNeo and might be a bit confusing:
> https://github.com/YottaSecond/thesisRepo
> 
> 
> On Sun, Apr 6, 2014 at 2:37 PM, Carlos Sanchez <csanchez126 at gmail.com> wrote:
> Hey list,
> 
> Thanks for your prompt replies and helpfulness!
> 
> I could not get qjackctl to work, the audio will not go through and the PD CPU load gets abnormally high at around 67%...
> I had already played with the sample rate and I had noticed that augmenting the frequency yields better results but the noise was still very present. 
> The sound card itself works correctly with Audacity so I am sure it would work with the arecord and aplay commands Brian suggested. Weirdly, it is only with PD that it is struggling...
> 
> On a more encouraging note, as Brian suggested, it seems that the problem (or one possibility) is the duplex audio. I haven't thought about using the card as an output only device before and it did work! But afterwards, I was not able to change the settings back and use the noisy duplex audio any more, I was only able to switch the output devices...
> 
> @Brian: What type of software are you using for the signal processing with the Raspberry Pi? I am very curious because I had first attempted to build this project on a BeagleBone Black but the heavy PD patches made it unstable or crash...
> 
> 
> 
> 
> On Sat, Apr 5, 2014 at 12:16 PM, Brian Fay <ovaltinevortex at gmail.com> wrote:
> If you haven't tried it already, try increasing the latency in the audio settings (probably not the issue, but worth a shot).
> 
> Maybe it's only having trouble with duplex audio (simultaneous input and output). Do you have both input and output enabled for your soundcard? Does it work if you only have the output device set, and leave the input device blank?
> 
> You can test to see if duplex audio is working outside of pd - try running "arecord | aplay" (the vertical bar means pipe the data from arecord into aplay), and see if you get usable sound. You may need to set some command line flags on those to get the sample rate and audio devices right, sorry I don't know them offhand.
> 
> I am running a fairly similar setup - for an honors project at my university, I'm using a Raspberry Pi and Behringer UCG102. I have a nice multi-effects pedal working at less than 20ms latency. If my Raspberry Pi can handle it, I feel like your UDOO quad should definitely be able to. I'd like to add that you have a nice taste in projects :)
> 
> 
> On Fri, Apr 4, 2014 at 10:41 AM, Carlos Sanchez <csanchez126 at gmail.com> wrote:
> Yes, I have tried changing sample rates and it has not solved the issue.
> 
> The sound card I am using is basically a copy of the Behringer UCG102 guitar to USB interface : http://www.behringer.com/EN/Products/UCG102.aspx
> 
> 
> 
> On Fri, Apr 4, 2014 at 8:40 AM, tim vets <timvets at gmail.com> wrote:
> and what is this 'Generic Guitar to USB' exactly?
> 
> 
> 
> 2014-04-04 3:09 GMT+02:00 Carlos Sanchez <csanchez126 at gmail.com>:
> Hello PD-list,
> 
> I am currently working on my semester project which is a guitar multi-effect pedal using the UDOO Quad and PD. I got everything up and running on the Linaro Ubutu 12.04 LTS build provided by UDOO and I am having strange results with PD. The soundcard I am using works normally when I am using Audacity. It plays wav files and can record the guitar signal correctly but when it comes to PD, a basic osc object or a table read through ALSA produces a strange digital noise, completely ruining the audio signal.
> 
> I have also tested this setup with a M-Audio Fast Track Pro USB card and the playback worked without issues, although I could not get the input signal through the adc object for an unknown reason. 
> 
> Has anyone tried a similar setup for guitar usage?
> 
> Thanks!
> 
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