AudioInjector installation - which way to go?

tom posted Aug 12 '19, 10:43:

Hi there,

I´m trying to install the AudioInjector hat. The ISO with SamplerBox built-in makes this hard. Issues are:

no raspi-config (Need to change locale or the keyboard drives me nuts)
no internet over ethernet (strange, I think it worked the first time I flashed the iso)
thus no apt-get update etc
basically nothing is installed. SSH via USB, no idea how to set this up.

I tried for a day to fix all this, then tried another sd with a fresh raspbian. That worked immediately, but I´m stuck on a few issues, path-to-samples, autostart, making sd read-only etc. I have absolutely no knowledge of linux and am quite happy to have made it this far.

Please tell me, will trying to fix these (minor) issues on a 2019-07-10-raspbian-buster-lite result in a playable SamplerBox? Or will there be latency and performance issues?

Thanks, Tom

tom posted Aug 12 '19, 12:12:

I found out how to change the device tree, hooray. Now the ISO works - but not samples. I´ll try to figure that out nex.

tom posted Aug 12 '19, 12:26:

Saved the mellotron on the sd card and renamed it to 0 Saw. That works. Latency seems to quite high though and sometimes midi gets stuck, midi off commands seem to slip though. Any ideas on that?

Cheers and thanks!


tom posted Aug 13 '19, 10:08:

Latency can be reduced by using this by Alex

One thing you could try is adding latency="low" to the parameters on this line:

(by default it's set to "high")

So instead it will read:

sd = sounddevice.OutputStream(device=AUDIO_DEVICE_ID, blocksize=128, samplerate=44100, channels=2, dtype='int16', callback=AudioCallback, latency="low")

I set polyphony to 8 and it works with blocksize of 128.

HansEhv posted Aug 15 '19, 01:51:

Hi Tom,
Using a raspbian includes quite some overhead not needed for samplerbox (samplerbox is a stripped version of debian linux). A full distribution will cause latency and missing events (=missing midi notes) etcetera.
You should get one of the available images working instead (4 available).
Indeed they don't have raspi-config (not needed).
SSH is via the network, not USB. So just plug in a cable and ssh to the new discovered samplerbox host in your network (in Windows use PuTTY). User=root, password=root.
You can also attach an hdmi display and usb keyboard to get to the commandline directly.
Hope this helps.

tom posted Aug 20 '19, 09:38:

Hi Hans, I did get the ISO to run in the meantime :) Thanks for your message though. The only issue left is this: Can I attach buttons on the GPIO? It´s already occupied by the Audio Injector hat. Are these pins still available or how can I switch samples a different way?

HansEhv posted Aug 21 '19, 12:43:

Hi Tom,
I think the audioinjector hat only uses the two pins of the I2C interface (but you need to check that in the docs with your card!). If so it won't interfere with the buttons in the various samplerbox builds as they do not use the I2C pins. If more pins are used and there is duplicate usage of a pin, the script or config file (depending build) can be changed to use other pins for your buttons.
It might interfere with I2C 7-segment display though (depends a bit on how both are implemented, this is beyond my knowledge).
All builds also support changing sample sets via midi program change, so if your device supports that, it is always a possibility. My alternative build also supports a webgui.


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