[mythtv-users] Sound volume from a PVR-500 (v4l)

[Jerome Yuzyk]

On Tuesday, January 28, 2020 7:02:25 PM MST Stephen Worthington wrote:
> On Tue, 28 Jan 2020 15:44:50 -0700, you wrote:
> >The last item on the recovery from my FE/BE blowing 3 caps after Christmas
> >is getting my PVR-500 capturing composite from my Shaw DCT-700 to have a
> >higher volume.
> >
> >Pre-crash, /dev/video0 was over-loud. Now it's the opposite: too quiet,
> >even jacking up playback volume.
> >
> >I turned to this method to try to fix it.
> >
> >http://gedakc.users.sourceforge.net/display-doc.php?name=pvr-volume-too-lou
> >d
> >
> >It involves creating a script to set the volume, and then making it a
> >"Master backend started" System Event.
> >
> >But it doesn't seem to have an effect and I'm kinda stumped.
> >
> >Even after I restart mythbackend, and presumably running the script,
> >
> >  v4l2-ctl --list-ctrls -d /dev/video0 | grep volume | tr -s " "
> >
> >returns
> >
> >  volume (int) : min=0 max=65535 step=655 default=60928 value=52400
> >
> >flags=slider
> >
> >when my script asks for the volume to be 60928. I'm out of ideas and
> >patience to flail on it at the moment.
> 
> Does the script need more permissions to set the volume?  Does it work
> when run with sudo?

The script, which does

    v4l2-ctl --set-ctrl volume=60298 -d /dev/video0

runs as my 'mythtv' user, and

    v4l2-ctl --list-ctrls -d /dev/video0 | grep volume | tr -s " "

then returns

     volume (int) : min=0 max=65535 step=655 default=60928 value=60260 
flags=slider

indicating that 'value' was set to what I want (limited by 'step').

I assume that mythbackend can run it as 'mythtv' or root.

-- 
A little of Jerome's MythTV World: http://mythtv.bss.ab.ca