Remaining low sound volume while vol/pcm are set to 0

[jcarnat]

Hi,

When I set vol and pcm to 0, there is still a low sound volume being played when watching videos using Librewolf or mpv. It sounds like there is a third mixer channel somewhere. The YouTube volume icon on Librewolf or changing volume using the mouse scrollwheel in mpv makes the volume vary without vol/pcm values from `mixer` being changed.

I'm using FreeBSD 14.2 with a USB soundbar. Both Librewolf and mpv were installed from quaterly binary packages.

For example, after setting vol and pcm to 1.00 using `mixer`:
- Using the volume icon from a YouTube video, I can turn the volume down to 0; while vol/pcm are still 1.00.
- Same thing happens using mpv and scrolling the mouse to have the volume vary. I can turn the volume to 0, no sound outputs but vol/pcm are still 1.00.

The other way around, if I set the volume to 100% using the YouTube volume icon or the scrollwheel in mpv:
- Using `mixer` and changing vol and/or pcm values does affect both Librewolf and mpv volume.
- But it can never really be turned silent using `mixer` - even when both vol and pcm are set to 0.00.

Both software seem to be using OSS as expected by default. Using `kldload snd_driver` doesn't solve the problem.
In case it helps, here's my sndstat output:

# cat /dev/sndstat
Installed devices:
pcm0: <Realtek ALC257 (Analog 2.0+HP/2.0)> (play/rec)
pcm1: <Realtek ALC257 (Right Analog Mic)> (rec)
pcm2: <Intel Kaby Lake (HDMI/DP 8ch)> (play)
pcm3: <DELL DELL Slim Soundbar SB522A> (play/rec) default
No devices installed from userspace.

Is this expected/known? Is there a way to get rid of this "additional" mixer or have it automatically aligned with vol or pcm value?

Thanks.

 

[Mirror176]

T recently noticed background noise during silence with headphones but I forget what device I found bringing it it. I'd experiment mixer to change each to be muted or unmuted and set to 0%, anything just above 0%, 75-80%, and 100%. different devices may bring in noise unexpectedly and mute vs 0% vs both sometimes worked differently for me. If you don't get the audio you wanted then try toggling unmute and 75% for all channels and try toggling which device is default. If you find such strange behavior on your system, put notes in a file for future you to remember without repeating all of the testing. I'd also consider looking at what shouldn't be used to make sure you don't have 2+ channels/devices all getting the audio. Adjusting audio with mixer should be able to fully silence the audio output unless it is noise coupled through the electronics after the chip.

Other than that, programs themselves and programs using other audio layers (pulseaudio, jack, etc.) are doing software adjusting/mixing before your audio chipset so their mixer rules may be uniquely handled. Some programs support selecting different audio routes through a runtime configuration, some require rebuilding the port manually with a different option, and some don't have a choice selectable by either method.