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

[Jerome Yuzyk]

On Wednesday, January 29, 2020 11:36:48 AM MST Jerome Yuzyk wrote:
> 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-l
> > >ou
> > >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.

Grrr... and even when the volume is set by v4l2-ctl, as root, and verified by 
the output of --list-ctrls, when a recording is made the volume is somehow set 
to 52480, and I can't find where that is happening!


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