[pulseaudio-discuss] changing default pulseaudio output device

[Tanu Kaskinen]

On Fri, 2015-05-15 at 16:33 +0100, Samuele Carcagno wrote:
> Hi,
> 
> thanks for the advice.
> 
> >
> > ...except that it seems that the KDE-specific routing system isn't
> > working either. It sounds like things just don't get saved on disk.
> >
> > Is this "KDE multimedia settings" the same as KMix? KMix should have a
> > list of "media roles", such as video, music, game, event etc. Each role
> > should have a list of audio devices, which you can prioritize by
> > reordering the list. Assuming that you have a similar settings in this
> > "KDE multimedia settings" thing, does the device-manager database
> > timestamp in ~/.config/pulse get updated after you change the device
> > priorities? (Wait 10 seconds before checking; the device-manager
> > database gets written to disk after a 10 second delay.)
> >
> > If the timestamp doesn't get updated, then module-device-manager doesn't
> > write anything to the disk. In that case, check if module-device-manager
> > is even loaded with "pactl list modules".
> 
> I've investigated a little more:
> 
> 1) the issue seems to be KDE specific, because if I use fluxbox then the 
> sink that I choose with pavucontrol sticks across reboots (to fluxbox, 
> but not KDE).

Ok. I don't have any idea what KDE is doing, and why it's doing it only
on your system (I don't think this is a widespread problem).

> 2) the module-device-manager seems loaded, this is the output of pactl 
> list modules:
> 
> Module #24
>          Name: module-device-manager
>          Argument: do_routing=1
>          Usage counter: n/a
>          Properties:
>                  module.author = "Colin Guthrie"
>                  module.description = "Keep track of devices (and their 
> descriptions) both past and present and prioritise by role"
>                  module.version = "5.0"

No problems there.

> 3) I'm not clear which file specifically is the device-manager database 
> in ~/.config/pulse. In there, there is a file called 
> '19c51c60c1f643f584a4a976530e28f8-device-manager.tdb' and its timestamp 
> does get update when I change the "KDE multimedia settings" (that's the 
> same interface you get if you choose audio setup in kmix). The settings 
> I choose stick if I logout and log back in, but if I reboot they don't 
> stick...

That's the right file. That file contains the device priorities that you
configure in KDE multimedia settings.

I can't think of any easy ways to debug this. module-device-manager
could be patched to dump the database in time-stamped human-readable
form somewhere every time the database changes, and if possible, log
also the application that does the change. That would hopefully reveal
the time where the database gets reset. But I don't think I have time to
write such patch.

-- 
Tanu