Audio stutter after update

[Johnny Izzo]

After some update:
Audio stutters in VLC
Video and audio stutters in Youtube

I think cpu usage might be bigger in VLC too, over 20% vs. below 20% earlier (one thread gets full 100%?)

Stuttering kernel at the moment is 4.15.0-46-generic.

Kernel version 4.15.0-43-generic definitely worked good.
Cant remember if i could get slight stutter from previous version version -45.

Tried also lowlatency and 4.18 kernel, bad stuttering in those.

(Distro is Lubuntu)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-46-generic 4.15.0-46.49
ProcVersionSignature: Ubuntu 4.15.0-46.49-generic 4.15.18
Uname: Linux 4.15.0-46-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.15.0-46-generic.
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 1: PCH [HDA Intel PCH], device 0: CX20751/2 Analog [CX20751/2 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: meie 855 F.... pulseaudio
 /dev/snd/controlC1: meie 855 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'HDMI'/'HDA Intel HDMI at 0xf711c000 irq 50'
   Mixer name : 'Intel Broadwell HDMI'
   Components : 'HDA:80862808,80860101,00100000'
   Controls : 35
   Simple ctrls : 5
Card1.Amixer.info:
 Card hw:1 'PCH'/'HDA Intel PCH at 0xf7118000 irq 47'
   Mixer name : 'Conexant CX20751/2'
   Components : 'HDA:14f1510f,1043181d,00100100'
   Controls : 20
   Simple ctrls : 9
CurrentDesktop: LXDE
Date: Sat Mar 16 18:02:18 2019
InstallationDate: Installed on 2018-07-04 (255 days ago)
InstallationMedia: Lubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 064e:9700 Suyin Corp. Asus Integrated Webcam
 Bus 001 Device 002: ID 8087:0a2a Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: ASUSTeK COMPUTER INC. UX305FA
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-46-generic root=UUID=a032fe2a-8284-47a9-a0d1-cfa1f01a5812 ro quiet splash vt.handoff=1
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-46-generic N/A
 linux-backports-modules-4.15.0-46-generic N/A
 linux-firmware 1.173.3
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/19/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: UX305FA.210
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: UX305FA
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrUX305FA.210:bd05/19/2015:svnASUSTeKCOMPUTERINC.:pnUX305FA:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnUX305FA:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
dmi.product.family: UX
dmi.product.name: UX305FA
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Johnny Izzo (izzostar)]

I mean the audio part of the video stutters in VLC.
(It's made with android phone and downloaded back from youtube.
Codec: H264 - MPEG-4 AVC (part 10) (avc1))

[Kai-Heng Feng (kaihengfeng)]

Would it be possible to find the last kernel version that doesn't have this issue?

[Johnny Izzo (izzostar)]

Yes, tried a few back now. 4.15.0-43-generic is the last good one.

-44 has the weird things, Youtube video goes slower (or stops for while) and then speeds too much and audio gets out of sync with that.

In VLC audio stutter starts at about after first 10 to 12 seconds.

[Kai-Heng Feng (kaihengfeng)]

Please attach dmesg when this issue happens.

[Johnny Izzo (izzostar)]

I would'nt say it happens, i'd say its always there constantly.

[Kai-Heng Feng (kaihengfeng)]

Does latest mainline kernel [0] have the issue?

If it does, then we need to bisect between 4.15.0-{43,44}.

[0] https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.1-rc2/

[Johnny Izzo (izzostar)]

5.1.0-050100rc2-generic, works great, does not have that issue.

Thanks, i'm keeping it!

[Johnny Izzo (izzostar)]

Hm, that was a bit early. Now it has "happened" ONCE with the 5.1.0-050100rc2-generic kernel.
I think the battery of the laptop was pretty low at the time.
Youtube audio went totally out of sync with video.

Restarted to 4.15.0-43 to see what that does with youtube. It had pauses in getting the video (the circle going round) but when picture came back it was still in sync with audio.

Restarted back to 5.1.0-050100rc2-generic again. Now everything was ok there.

Also computer shows i have powersave governor on.
Another notebook with (Celeron N3350 and) powersave has no problems at all though.
I should probably also try a clean install.