[USB-Audio - RODECaster Pro, playback] Sound is distorted (21.04)

[Oliver Tacke]

I got a Rodecaster Pro USB device that has been causing trouble before and already lead to quirk handling in the kernel for the sample rate, see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/usb/format.c?h=v5.8#n412

The Rodecaster is running fine on my laptop, but on my desktop, only audio input is working. The audio output is distorted. It's played kind of very slowly. Interestingly, if the source is a video file, the video plays slower, e.g. YouTube in a browser. I have never seen anything like that before.

I have tried to figure out what the cause might be and I think I have reached the end of where I can get to on my own. I have documented most things at https://ubuntuforums.org/showthread.php?t=2461568

Putting my last step it in a nutshell: I have booted both my computers with a plain Ubuntu 21.04 from a pen drive (it uses kernel version 5.11.0-16-generic) to make sure it's not some different configuration that I have set up over the years on my systems (both Ubuntu 20.04 with kernel 5.8.18). I attached the Rodecaster. It runs fine on my laptop, but not on my desktop (used the output test from).

I then detected the card number with

aplay -l

I killed pulseaudio with

pulseaudio -k

I then played the same sample (encoded in 48000 Hz in PCM signed 32 bit little endian format) using

aplay -f S32_LE -c 2 -r 48000 -D hw:x ~/sample.wav

where x is the appropriate card number and the rest of the arguments meet the Rodecaster's narrow specification. It's playing fine on the laptop, but distorted on the desktop. As far as I understand using aplay this way without a plugin should send the file directly to the device, so I assume there's something on the way from aplay to the Rodecaster that's interfering (kernel or even some piece of hardware) - and that definitely is where my expertise ends (rather a little before :-)).

I'll gladly contribute any information that could be useful and I will willingly help to debug this problem if it may be related to the kernel. If there's anything I can do, please let me know.

Cheers,
Oliver

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: alsa-base 1.0.25+dfsg-0ubuntu7
ProcVersionSignature: Ubuntu 5.11.0-16.17-generic 5.11.12
Uname: Linux 5.11.0-16-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu65
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.461
CurrentDesktop: ubuntu:GNOME
Date: Thu May 6 09:33:40 2021
LiveMediaBuild: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:Pro failed
Symptom_Card: RODECaster Pro - RODECaster Pro
Symptom_Type: Digital clip or distortion, or "overdriven" sound
Title: [USB-Audio - RODECaster Pro, playback] Sound is distorted
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/30/2020
dmi.bios.release: 5.17
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: A.40
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: B550-A PRO (MS-7C56)
dmi.board.vendor: Micro-Star International Co., Ltd.
dmi.board.version: 1.0
dmi.chassis.asset.tag: To be filled by O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Micro-Star International Co., Ltd.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrA.40:bd10/30/2020:br5.17:svnMicro-StarInternationalCo.,Ltd.:pnMS-7C56:pvr1.0:rvnMicro-StarInternationalCo.,Ltd.:rnB550-APRO(MS-7C56):rvr1.0:cvnMicro-StarInternationalCo.,Ltd.:ct3:cvr1.0:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: MS-7C56
dmi.product.sku: To be filled by O.E.M.
dmi.product.version: 1.0
dmi.sys.vendor: Micro-Star International Co., Ltd.

[Oliver Tacke (otacke)]

I have now built in a separate PCIe board with USB ports that do not rely on AMD chipsets. The RODECaster Pro now works perfectly. So this seems to be in fact something out of the audio driver's responsibility (?) and needs to be fixed somewhere else?

It' sad that I lost one port, but at least there's a new trace to where the cause might be. Hopefully, this can be fixed in software, too.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Tyler Tolley (thattolleyguy-s)]

I have the same issue.