Bug 335307

Summary:	Wrong Master Channel (after upgrade, keyboard shortcuts broken, volume 0% (icon completely transparent))
Product:	[Applications] kmix	Reporter:	Philippe Cloutier <chealer>
Component:	general	Assignee:	Christian Esken <esken>
Status:	RESOLVED WAITINGFORINFO
Severity:	major	CC:	postix
Priority:	NOR
Version First Reported In:	4.5
Target Milestone:	---
Platform:	Debian testing
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Philippe Cloutier 2014-05-25 06:13:53 UTC

I'm experiencing a very confusing bug with KMix, which is trivial to workaround once you understand it, but which took me nearly half an hour to figure out. I'm 90% confident that this bug appeared just after a partial upgrade from KDE 4.12 to 4.13.1. All users are affected.

I realized something changed in KMix's systray icon. I thought that was intentional and tested KMix, which made me realize it didn't work normally. The icon was entirely transparent, no matter what the volume was set to. The scrollwheel didn't change the volume anymore. Multimedia shortcuts (mute, increase/decrease volume) didn't work anymore. Yet, KMix still did its job fine if I adjusted the volume using the scrollbar, either via the systray or after bringing up the mixer. I eventually understood from the OSD which appears when trying to use shortcuts and from the systray's tooltip that some channel was stuck at 0% volume.

I have 2 "sound cards" on this desktop, one integrated in the motherboard, and one from HDMI, which is shown first for some reason. The are currently no channels on the HDMI card (probably a kernel issue). The workaround is simply to select a master channel which exists (right-click on the systray icon). When I first entered "Select Master Channel...", the current mixer was "HDA ATI HDMI". By changing this to "HD-Audio Generic 2", I was able to define its "Master" channel as the master channel and to get KMix back to normal.

In other words, it seems KMix was "using" a non-existent channel on the HDMI card as its master channel. Since it doesn't exist, the volume level was always 0. Once I changed the master channel, I can't get KMix back to that "phantom channel", since I can't select any channel on the HDMI card.

I use Debian testing. The upgrade I did included kdelibs and KMix. I assume this is related to the fact that I am now hit by bug 332177.

Comment 1 Christian Esken 2014-08-14 21:06:43 UTC

It is not be a new problem, as far as I can say. On first start, KMix picks the first card and selects the most appropriate control from it. This is bad, if the first does not contain controls with a playback volume. I have just encountered the same issue on my new Laptop, and the results are obviously not nice.

I am currently on a cruise to optimize all these topics. Unfortunately I did not manage to do this during the KDE Multimedia Sprint 2014 in Randa (currently there, about to leave in a couple of hours). Likely I will try to fix this.

Assigning ticket.

Comment 2 Christian Esken 2014-08-14 21:20:32 UTC

As a side note, I just introduced a command line option to reset KMix's settings, and thus to start as if it would be the first start (without reading configuration file kmixrc and GUI profiles). Very comfortable for testing issues like these. Just run:
   kmix --failsafe

Comment 3 Justin Zobel 2021-03-10 00:16:18 UTC

Thank you for the bug report.

As this report hasn't seen any changes in 5 years or more, we ask if you can please confirm that the issue still persists.

If this bug is no longer persisting or relevant please change the status to resolved.

Comment 4 Philippe Cloutier 2021-03-12 01:01:55 UTC

I still own the affected machine, but it is now my third PC, it uses a much different Linux version, and it does not even run Debian anymore. I do not remember seeing this bug ever come back.

Considering that no one else has reported experiencing this bug in this ticket, I guess the chances this would have been a migration bug specific to a certain version upgrade are considerable. Unfortunately, as the exact reproduction  conditions remain unknown, confirming persistence with testing would be difficult.

Comment 5 postix 2022-05-18 13:25:45 UTC

(In reply to Philippe Cloutier from comment #4)
> I still own the affected machine, but it is now my third PC, it uses a much
> different Linux version, and it does not even run Debian anymore. I do not
> remember seeing this bug ever come back.
> 
> Considering that no one else has reported experiencing this bug in this
> ticket, I guess the chances this would have been a migration bug specific to
> a certain version upgrade are considerable. Unfortunately, as the exact
> reproduction  conditions remain unknown, confirming persistence with testing
> would be difficult.

I guess this can be closed then. Should you or someone else encounter it again, please feel free to reopen. :)

Comment 6 Philippe Cloutier 2022-05-23 15:57:08 UTC

Why was this marked "NOT A BUG"?