https://bugs.kde.org/show_bug.cgi?id=526143
Bug ID: 526143
Summary: Opening the audio volume widget activates my headsets
(Sennheiser Momentum 5) dongles (BTD 700) microphone
and switches the headphone out of aptX Adaptive to a
much less quality codec
Classification: Plasma
Product: plasmashell
Version First master
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: Audio Volume widget
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: 1.0
DESCRIPTION
Opening the KDE Plasma "Audio Volume" widget in the system tray causes my
Sennheiser BTD 700 Bluetooth transmitter to activate its capture device. This
makes my Sennheiser Momentum 5 headphones leave their normal aptX Adaptive
audio mode and enter a call/voice state.
The problem occurs only while the Audio Volume popup is open. As soon as the
popup is closed, the headphones return to normal aptX Adaptive operation.
STEPS TO REPRODUCE
1. Connect the Sennheiser Momentum 5 through the BTD 700.
2. Confirm that the headphones are operating normally using aptX Adaptive.
3. Close the KDE Audio Volume popup.
4. Open the Audio Volume popup from the KDE system tray.
5. The headphones immediately produce an audible notification and switch out of
aptX Adaptive.
6. In Sennheiser Smart Control Plus, aptX Adaptive is no longer shown as active
and the device reports a call/no-audio-stream state.
7. Close the Audio Volume popup.
8. Ater a few moments, the headphones return to normal aptX Adaptive operation.
OBSERVED RESULT
EXPECTED RESULT
Opening the audio volume widget should not activate an audio input/capture
stream merely to display the volume controls or input level and opening the
widget should not cause a bluetooth audio device to enter a call/voice profile
when nothing is using the mic
SOFTWARE/OS VERSIONS
Operating System (available in the Info Center app, or by running `kinfo` in a
terminal window):
KDE Plasma Version: 6.7.5
KDE Frameworks Version: 6.30.0
Qt Version: 6.11.2
PipeWire: 1.6.8
WirePlumber: 1.6.8
ADDITIONAL INFORMATION
*the following was made by chatgpt (sorry) but I read it and I agree with all
of it*
Opening the Audio Volume widget creates PlasmaPA-VolumeMeter streams that
access the BTD 700 capture device.
I confirmed this using wpctl status while the popup was open. It showed streams
such as:
[PlasmaPA-VolumeMeter]
... input_MONO < BTD 700:capture_MONO [active]
and:
[PlasmaPA-VolumeMeter]
... input_FR < BTD 700:monitor_FR [active]
... input_FL < BTD 700:monitor_FL [active]
The BTD 700 capture node itself is:
node.description = "BTD 700 Mono"
node.name =
"alsa_input.usb-Sennheiser_BTD_700_09B88CA9ED0F1BAB3C08-02.mono-fallback"
media.class = "Audio/Source"
api.alsa.pcm.stream = "capture"
audio.channels = "1"
I also inspected one of the Plasma volume-meter nodes:
application.id = "org.kde.plasma.plasma-pa"
application.process.binary = "plasmashell"
media.class = "Stream/Input/Audio"
media.name = "PlasmaPA-VolumeMeter"
(The exact PipeWire object IDs are dynamic and therefore change between
sessions.)
Additional testing
I tested the WirePlumber setting:
wpctl settings bluetooth.autoswitch-to-headset-profile false
The setting was successfully changed to false, but opening the Audio Volume
widget still caused the same behavior.
I also muted the BTD 700 capture device with:
wpctl set-mute 115 1
Opening the Audio Volume widget still caused the headphones to switch modes.
Therefore this does not appear to be caused simply by the microphone being
unmuted.
I restored the microphone afterwards with:
wpctl set-mute 115 0
No permanent WirePlumber configuration was added.
Why I believe the Audio Volume widget is responsible
The behavior is directly correlated with the lifetime of the
PlasmaPA-VolumeMeter streams:
Audio Volume popup closed → no Plasma volume-meter capture stream → aptX
Adaptive works normally.
Audio Volume popup opened → PlasmaPA-VolumeMeter accesses BTD 700 capture →
headphones enter call/voice state.
Audio Volume popup closed → capture stream disappears → headphones return to
aptX Adaptive.
This appears to make the widget's volume/input-level monitoring activate
Bluetooth capture even though no application is actually recording from the
microphone.
Regression / impact
This is particularly problematic with Bluetooth transmitters/headsets because
opening the system audio controls can unexpectedly force the Bluetooth device
into a lower-quality call/voice mode.
It also means that simply opening the KDE Audio Volume widget changes the audio
behavior of the system, even when no application is requesting microphone
access.
Related observation
The PlasmaPA-VolumeMeter streams appear to be involved in other Audio Volume
widget behavior as well. I would appreciate it if this could be investigated so
that opening the widget does not unnecessarily activate capture devices.
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