c920 powerline frequency setting

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
Post Reply
gi7ugv
Posts: 50
Joined: Tue Oct 31, 2017 2:47 pm

c920 powerline frequency setting

Post by gi7ugv » Tue May 14, 2019 1:11 pm

I just got around to looking at the flickering I was seeing on the c920 in Linux and it turned out to be an easy fix.

There is a power line frequency setting in the camera that defaults to 60Hz that with my lighting and walls ends up looking pretty bad. Figure changing this might be handy for other users and the Portsdown too, it doesn't survive a reboot so will need set on startup.

You can view the current setting selecting the correct video device:

Code: Select all

v4l2-ctl -d /dev/video0 --all| grep freq
           power_line_frequency (menu)   : min=0 max=2 default=2 value=2
"power_line_frequency" set to 1 selects 50Hz, while set to 2 (default) it is 60Hz.

It is easy to change with:

Code: Select all

v4l2-ctl -d /dev/video0 --set-ctrl power_line_frequency=1
The following video shows changing between the two on a Portsdown TX with the c920 in webcam mode starting off on the default 60Hz.

https://youtu.be/wvam7bu9Bz8

G8GKQ
Site Admin
Posts: 2798
Joined: Sun Mar 22, 2009 1:21 pm

Re: c920 powerline frequency setting

Post by G8GKQ » Tue May 14, 2019 1:59 pm

Thanks John

I can put that in the next release, and only implement it for PAL users.

Really useful!

Dave

Post Reply

Return to “The Portsdown Digital ATV System”