module-equalizer-sink produces cracking at the beginning of playback

[Vincas Dargis]

After upgrade from Kubuntu 14.04 to Kubuntu 16.04 (amd64), audio playback contains cracking, especially noticeable when sound/video file is seeked (on SMplayer, Youtube on Firefox), or new notification sound plays in IM clients (in Skype, qTox, ...).

Usually cracking stops shortly, though some times it goes for long time, until "killall pulseaudio" is initiated.

Once "load-module module-equalizer-sink" line is commented-out and system rebooted, everything returns back to normal playback without distortions.

When -vvvv is added into client.conf to extra arguments, syslog contains some interesting lines about underrun, which might be relevant:

Dec 18 21:47:34 tomas-Z87X-SLI pulseaudio[2324]: [alsa-sink-ca0106] sink.c: alsa_output.pci-0000_05_01.0.analog-surround-40: Found underrun 3800 bytes ago (34600 bytes ahead in playback buffer)
Dec 18 21:47:34 tomas-Z87X-SLI pulseaudio[2324]: message repeated 3 times: [ [alsa-sink-ca0106] sink.c: alsa_output.pci-0000_05_01.0.analog-surround-40: Found underrun 3800 bytes ago (34600 bytes ahead in playback buffer)]

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: pulseaudio 1:8.0-0ubuntu3.1
ProcVersionSignature: Ubuntu 4.4.0-53.74-generic 4.4.30
Uname: Linux 4.4.0-53-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
CurrentDesktop: KDE
Date: Sun Dec 18 21:41:52 2016
InstallationDate: Installed on 2014-12-07 (741 days ago)
InstallationMedia: Kubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: pulseaudio
UpgradeStatus: Upgraded to xenial on 2016-08-05 (134 days ago)
dmi.bios.date: 06/12/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F3c
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z87X-SLI
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: To be filled by O.E.M.
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF3c:bd06/12/2014:svnGigabyteTechnologyCo.,Ltd.:pnZ87X-SLI:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ87X-SLI:rvrTobefilledbyO.E.M.:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.name: Z87X-SLI
dmi.product.version: To be filled by O.E.M.
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
modified.conffile..etc.pulse.default.pa: [modified]
mtime.conffile..etc.pulse.default.pa: 2016-12-18T21:14:16.931919

[Vincas Dargis (talkless)]

Attached syslog with verbose pulseaudio logs. I was clicking "Make a test sound" on Skype, skipped audio file on SMPlayer etc, so that short sound cracking is produced.