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More => Old Versions => JRiver Media Center 29 for Linux => Topic started by: scrutinizer on November 13, 2022, 09:50:06 am

Title: Latest Kernel - USB Audio sound quality?
Post by: scrutinizer on November 13, 2022, 09:50:06 am
Not sure if it's the right place for this but still,
I'm using JRiver on Debian stable with some extra backports.

For a while I struggled with a strange phenomenon of sound quality "changes" over time (hours/days)
using USB DACs (Arcam irDAC / Denafrips Ares II).
The sound was great at times and gradually became tainted/clouded for an unknown reason.

That went on until the recent backports kernel upgrade to version 5.19.11.
This upgrade has completely transformed the Denafrips Ares II sound quality, which now performs as it should and shows its true potential. No more sound changes over time. Everything is rock solid and sounding great.

I'm using the direct (hw) interface and there were no other changes.

What kernel change can cause this drastic improvement?
I thought the kernel doesn't affect the sound quality in itself and only brings the device to a working state.

Any hints?
Thanks
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: eve on November 13, 2022, 12:19:38 pm
Following
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: bob on November 14, 2022, 05:23:49 pm
If you are using the hw: driver, MC tells ALSA to do absolutely no processing of the signal so I don't know why a different kernel should sound different.
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: eve on November 15, 2022, 02:24:43 pm
If you are using the hw: driver, MC tells ALSA to do absolutely no processing of the signal so I don't know why a different kernel should sound different.

Yeah.

Even more interestingly, these are standard class compliant USB audio devices. I just don't know what would change between kernel versions in that situation. Sure, some of more esoteric audio devices require kernel modification but these do not.
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: scrutinizer on November 18, 2022, 08:26:29 am
Yet it changes.
Reverting to an older version hurts the sound quality - bringing it back to the previous state.
Could it be some timing issue between the kernel and the usb device?

I really don't understand how it can be but that's what's going on.
Have there been any usb-audio specific changes in this kernel version?
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: mwillems on November 18, 2022, 09:22:18 am
FWIW I've been using Linux for USB audio since kernel version 3.2 up through 5.19, and a few of my systems are now on kernel version 6.0. I've never noticed any USB sound quality changes in any kernel versions, except in the case of one piece of hardware that was misbehaving prior to kernel 5.0 (i.e. that piece of equipment had loud obvious dropouts caused by buffer underruns, which stopped after 5.0). 

They're always improving the kernel, but assuming the hardware is working correctly, I would be hesitant to expect any subtle changes in sound quality.  If you're convinced you've spotted a change,  it will be hard to narrow down what happened because every single minor kernel version has changes to the USB audio subsystem.  Maybe step through the minor kernel versions and see if you can bisect the exact version at which the change occurred?
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: scrutinizer on November 22, 2022, 10:14:56 am
FWIW I've been using Linux for USB audio since kernel version 3.2 up through 5.19, and a few of my systems are now on kernel version 6.0. I've never noticed any USB sound quality changes in any kernel versions, except in the case of one piece of hardware that was misbehaving prior to kernel 5.0 (i.e. that piece of equipment had loud obvious dropouts caused by buffer underruns, which stopped after 5.0). 

They're always improving the kernel, but assuming the hardware is working correctly, I would be hesitant to expect any subtle changes in sound quality.  If you're convinced you've spotted a change,  it will be hard to narrow down what happened because every single minor kernel version has changes to the USB audio subsystem.  Maybe step through the minor kernel versions and see if you can bisect the exact version at which the change occurred?

The change happened after the 5.19.11 update in the Debian backports.
I regularly updated to every version that appeared in the backports. The only kernel version that exhibit this change is 5.19.11. Nothing prior.

Not noticing any change in terms of audio quality since 3.2 - That's the behavior I was expecting.
This goes against my understanding of how things work, but still there's a change, and not a subtle one. That's what I'm trying to understand.
Title: Re: Latest Kernel - USB Audio sound quality?
Post by: anonymous on January 11, 2023, 03:08:32 pm
New Linux kernels may get a bug and if the kernel is constantly updated the kernel one might pass through one and a change might be noticed afterwards. The links below speak of a known or suspected USB audio bug in Linux kernels 5.15.68 to 5.15.70 and 5.19.9 to 5.19.11. Updates don't always fix issues, but sometimes create them.

https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2703
https://bugzilla.kernel.org/show_bug.cgi?id=216500


In general, updating the kernel in Debian stable is never recommended, as it can impact the OS stability (Debian stable being someone akin to a reliable rock).