Audio noise from HDMI input ?

I had an issue with the mic during the rehearsal as a speaker at the "Embedded, Mobile and Automotive. After switching and using another mic the talk went smooth. I guess it might be related to noise on HDMI . I am using Lenovo T480S with Ubuntu 18.04.3 LTS and Linux kernel:

Linux leon-ThinkPad-T480s 4.15.0-76-generic #86-Ubuntu SMP Fri Jan 17 17:24:28 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Best regards, Leon

krokodilerian commented 4 years ago

If If you can note the room you were in, that'll also help, as there are some rooms with known electrical problems, which would contribute to that. Also, if anyone had disconnected their power supply and still had noise, it'd be very interesting (as a lot of times just working on battery resolves the issue).

rzr commented 4 years ago

I am unsure @leonanavi ( https://fosdem.org/2020/schedule/event/ema_homebridge_with_yocto/ ) faced the same issue that I observed with @mte90 laptop ( https://fosdem.org/2020/schedule/event/how_to_get_fun_with_teamwork/ )

the noise appeared when laptop was plugged into hdmi and stopped when unpluged.

ps: There were also some audio glitches in JS room but problem is not related to FosdemVideoBox

leon-anavi commented 4 years ago

Hi @krokodilerian,

I was at UD2.218A.

Thanks, Leon

Mte90 commented 4 years ago

Yes exactly, there was this kind of electronic noise, it is strange because I use this laptop since years as speaker at fosdem without issues. I don't know if it is a problem with my linux kernel running on that.

Let me know I can help, about laptop info or testing

libv commented 4 years ago

This has little to do with the new video hardware we are developing.

Then, audio is transmitted as a digital signal inside the blanking area of the display signal. HDMI noise is a bit hard to explain.

But having said that, i noticed noise coming from the loudspeakers in a K devroom when attaching the camera to the front desk panel (while testing a camera with a wonky hdmi connector).

Was the laptop's mixer set to pass a microphone or similar input through to hdmi, and then feeding back the introduced noise?

Anyway, not an issue for here, please mail video@fosdem.org.

FOSDEM / video-hardware

Audio noise from HDMI input ? #5