ALSA input error

[Gianluca Grazioli]

Hi,
I've been trying to use a Raspberry Pi as a guitar pedal, with the Satellite framework. I'm having some problems with the audio input of the soundcard.

- the audio output is fine, if I launch a Pure Data patch which doesn't use the audio input (so without the adc~ object), it works fine
- if I try to use the adc~ object, setting the audiocard input from the Audio Settings, this error come out: ALSA input error (snd_pcm_open): Device or resource busy.
- the curious thing is that if I connect an audio source to the audio input of the soundcard, I can hear the sound from the output, even with PD closed.

Does anybody have a suggestion?
thanks

[Gavin Morris]

You need to get a soundcard which will work with in & out simultaneously with pd/satellite/pi

Its tricky.

Search this list for duplex audio.

[Gianluca Grazioli]

Hi,
thanks for your reply.
Actually seems that my audiocard doesn't support the duplex mode, even though I can hear the input signal when PD is not running (this sounds silly...)

[Gianluca Grazioli]

Hi,
I've just tried this card
http://www.amazon.com/Syba-SD-CM-UAUD-Adapter-C-Media-Chipset/dp/B001MSS6CS

which should be a duplex one because it's been used in this project with RPi https://www.youtube.com/watch?v=bLcW70tcBX8
but I'm still having the same problem with Pure Data - ALSA input error (snd_pcm_open): Device or resource busy.
It's silly because I can hear the sound if I connect an instrument, just it doesn't enter  in Pure Data.

Any suggestion?

On Sunday, 24 July 2016 20:18:40 UTC+2, Gavin Morris wrote:

[Edgar J. Berdahl]

Make sure that you don't accidentally have any other pd patches running in the background.

Also, try monkeying with the latency settings in pd. Some sounds interfaces only work at shorter latencies or only at longer latencies.

When you are monkeying with this, use the "hardware" interface addresses of these devices instead of the software/plughw address, because that just adds more software layers between pd and the sound interface.

Finally, make sure that the number of channels matches up right. Sometimes it's unclear whether a USB audio interface has one input channel or two.

If all else fails, try getting it to work in output mode only at first.

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[Edgar J. Berdahl]

I personally recommend the Behringer UCG102 if you can find one.

—Edgar

On Friday, August 12, 2016 at 3:41:57 PM UTC-5, Edgar J. Berdahl wrote:

Make sure that you don't accidentally have any other pd patches running in the background.

Also, try monkeying with the latency settings in pd. Some sounds interfaces only work at shorter latencies or only at longer latencies.

When you are monkeying with this, use the "hardware" interface addresses of these devices instead of the software/plughw address, because that just adds more software layers between pd and the sound interface.

Finally, make sure that the number of channels matches up right. Sometimes it's unclear whether a USB audio interface has one input channel or two.

If all else fails, try getting it to work in output mode only at first.

[Gianluca Grazioli]

Dear Edgar,
thanks for your suggestions, I'll try them ASAP. In this days I've used the audiocard that I mentioned ( http://www.amazon.com/Syba-SD-CM-UAUD-Adapter-C-Media-Chipset/dp/B001MSS6CS ) with Raspberry Pi 1 Model B and it works well. It didn't give me the same problems that I had with Raspberry Pi 2. Also, I've been able to set PD in nogui mode thanks to the instructions set to this post https://puredata.info/docs/faq/commandline

So, with RP1ModelB all worked well and I've been able to run a guitar PD patch autonomously, as you can see in this video.

https://youtu.be/erjcxi6Il10

Thanks for your help and for having shared the methods of Satellite project. Without those, I wouldn't been able to build this device in so little time.

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