Hi Rafael,
The sound file you sent in your previous message ("[AudioI] Distortion in the sound of audio Injector octo") is horrible. Your problem could be caused by a mismatch between the analog outputs of the Octo and the analog inputs of your amplifier... If you lower the output volume of the Octo, does it sound better? What kind of audio file and what software are you using? It's difficult to help from email...
My solution was to fix a problem with the inputs (the outputs
where fine), but it may solve your problem too. Sound on Linux can
be affected by many things, like too much Desktop activity. Using
a low latency kernel and tuning the OS can help a lot. Using a
realtime kernel for ensuring realtime priorities of sound
processing can help even more. Of course it's easier to fix such
problems with some experience of Linux; explaining all the steps
would be too long, so you can check the links I sent, it worked
for me...
Marc
P.S. I once visited UNAM and experienced the MUAC Sound Camera.
:-)
Hello, I also have the problem with the distortion, but in my case this happen when I reproduce some audio file. Do you know, how solve this? I am in a Raspberry Pi 4 with Bullseye
El 13 jul 2023, a las 14:54, Marc Lavallée via People <people@lists.audioinjector.net> escribió:
Here's my solution with an OS based on RaspiOS Bullseye (with kernel 6.1).
A quick way to check if the inputs are saturated by noise:
$ arecord -c 6 -f S24_LE -V mono -r 96000 /dev/null
Recording WAVE '/dev/null' : Signed 24 bit Little Endian, Rate 96000 Hz, Channels 6
##################################################+| MAXIn my case, the result is the same with all combinations of number of channels, sample resolution, sampling rate, and input levels.
Because the Linux images included in the RaspiOS distributions (that can be installed from apt) are missing the required overlays, I installed a Linux kernel version 5 made specifically for the RPI: https://github.com/kdoren/linux/wiki
I installed the arm64 PREMPT_RT version because it prefer it for audio, but it's not required.
Then I tuned the OS for audio with help from this script: https://pypi.org/project/rtcqs/
Here's more tuning info, specifically for the RPI: https://wiki.linuxaudio.org/wiki/raspberrypi
The above arecord command will show a VU meter that momentarily go up to MAX, then it quickly go down to 0%; this is a known issue when initializing the Octo for recording. When using a sound server like Jack, the inputs of the Octo are initialized when the server starts, so that could be a way to avoid spikes when recording from jack.
I hope it helps (until the issue is solved for kernel 6).
Marc
Le 2023-07-12 à 08 h 01, Fabricio de Abreu Bozzi a écrit :
Hi Marc,
yes, I can try the suggested kernel.
thanks.Fabricio
On Wed, Jul 12, 2023, 08:51 Marc Lavallée via People <people@lists.audioinjector.net> wrote:
Le 2023-07-12 à 07 h 42, I wrote :
> Hi Fabricio,
>
> Can you try with an earlier OS using a kernel version 5.10+, for
> example one based on Debian Buster?
>
> https://downloads.raspberrypi.org/raspios_armhf/images/raspios_armhf-2021-11-08/
>
Oops! The link I sent for the OS based on Bullseye, here's the link for
the OS based on Buster (with kernel 5.10+):
https://downloads.raspberrypi.org/raspios_armhf/images/raspios_armhf-2021-05-28/
Marc
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