TrimUI Brick - fading/cutting out sound

[gopgnz]

Knulli build version

knulli-a133-trimui-brick-firefly-20241229
knulli-a133-trimui-brick-firefly-20250114

Your architecture

TrimUI Brick

Issue description

I got the TrimUI Brick + Knulli to use for an M8 headless setup. By adding a teensy 4.1 to the Brick I can use it as a music making device.
Me, as well as other owners of the Brick who got it for the same reason are experiencing an audio issue right now.

When the audio volume reaches a certain low threshold the audio simply cuts out.

I hope this can be fixed because other than that Knulli is incredible!

Detailed reproduction steps

This happens to all sounds at a certain volume level and no matter what the device volume is set to. If the device volume is all the way up and there happens to be a quiet sound in a track it suddenly cuts out. If I turn down the device volume altogether the issue becomes apparent across all audio.

This issue doesn't just apply to the M8C port but also to games. The stock OS doesn't exhibit this behaviour so presumably this has to do with the sound firmware inside of Knulli.

Details of any attempts to fix this yourself

A helpful person on the M8 & Knulli discord @mnml figured out a temporary fix through this: #264. An "overlay" file is created and placed in the boot folder. Then audio.headphone=5 is added "batocera.conf". After restarting the device the overall audio volume via headphones is lower. But now the sound doesn't cut out when it hits that low threshold. This fix definitely helps.

Details of any modifications you have made to Knulli.

M8C (a port inside portmaster)

Logs and data

No response