Roland GR-55 USB Audio

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merlyn
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Joined: Thu Oct 11, 2018 4:13 pm

Roland GR-55 USB Audio

Postby merlyn » Thu Jul 18, 2019 10:08 pm

Using Drumfix's quirk-table.h addition my GR-55 now appears in arecord -l.

I can select it to start JACK and JACK starts using 1024 frames and 3 periods.

The sample rate is always 44.1k regardless of what I choose in Cadence > Configure.

There is a steady stream of Xruns -- they just keep ticking up. JACK won't use the GR-55 as an output -- the output always falls back to my PCI soundcard, which is working, I can use the GR-55 MIDI to trigger Ninjas2 in Ardour. That makes sense -- I wouldn't want the GR-55 as an output.

I connected the GR-55 audio ins to a stereo track in Ardour and unfortunately there is nothing.
Last edited by merlyn on Mon Jul 29, 2019 9:35 am, edited 1 time in total.

merlyn
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Joined: Thu Oct 11, 2018 4:13 pm

Re: GR-55 USB Audio

Postby merlyn » Fri Jul 19, 2019 1:49 am

I got it working! Thanks Drumfix!

It works when the GR-55 is the input and the output. So at the moment my guitar synth is my soundcard. :!: That means in a live setup you could plug the synth into a laptop and have the laptop audio come out the synth into the amp you're using for the synth.

The sample rate is still always 44.1k.

tavasti
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Re: GR-55 USB Audio

Postby tavasti » Fri Jul 19, 2019 6:12 am

If you want, you can use your laptop as default interface, and use alsa_in / alsa_out to make additional jack interfaces, and route sounds like you desire in qjackctl / patchage / whateverappyoumayuse.
Linux veteran & Novice musician

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merlyn
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Joined: Thu Oct 11, 2018 4:13 pm

Re: GR-55 USB Audio

Postby merlyn » Fri Jul 19, 2019 10:33 am

Thanks @tavasti.

I've found alsa_in needs a large resampling buffer and therefore a high latency to work without Xruns.

merlyn
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Posts: 405
Joined: Thu Oct 11, 2018 4:13 pm

Re: Roland GR-55 USB Audio

Postby merlyn » Mon Jul 29, 2019 10:03 am

I updated my kernel to 5.2.0-rt1-1-rt and my GR-55 is recognised as an audio device without recompiling snd-usb-audio.

Looking through quirks-table.h there is no reference to the GR-55, so it must be this generic Roland quirk :

Code: Select all

/* this catches most recent vendor-specific Roland devices */
{
   .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
                  USB_DEVICE_ID_MATCH_INT_CLASS,
   .idVendor = 0x0582,
   .bInterfaceClass = USB_CLASS_VENDOR_SPEC,
   .driver_info = (unsigned long) &(const struct snd_usb_audio_quirk) {
      .ifnum = QUIRK_ANY_INTERFACE,
      .type = QUIRK_AUTODETECT
   }
},

This could have gone into the kernel a while ago as I wasn't checking if the GR-55 audio worked every time I updated my kernel.

Using the GR-55 as a USB audio device is of limited use to me as it only works at 44.1k and I record instruments other than the GR-55. Still, good to know it's there as an option.

MIDI works and can be hotplugged. MIDI has worked since kernel 3.13 on KXStudio.


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