It's all very confusing with many people experiencing similar symptoms. But the original logs look like a simple case of PulseAudio selecting a far too short latency:
I: protocol-native.c: Final latency 201.00 ms = 0.50 ms + 2*100.00 ms + 0.50 ms D: alsa-sink.c: Cutting sleep time for the initial iterations by half. D: alsa-sink.c: Latency set to 0.50ms And indeed, VLC version 1.1.8 requested tlength=200ms and minreq=100ms. A similar problem affects more recent VLC versions with tlength=40ms and minreq=-1 (overriden by PA to 20ms). It seems that when tlength is exactly twice minreq, PulseAudio settles on an insanely small latency. That causes frequent underrun in hardware buffers, accounting for the distorsion. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to pulseaudio in Ubuntu. https://bugs.launchpad.net/bugs/751265 Title: pulseaudio distorts VLC audio Status in “pulseaudio” package in Ubuntu: Confirmed Bug description: Binary package hint: pulseaudio Audio quality full of hiss (similar to what it might sound like if you pulled your headphone/speaker plug out halfway). The hiss distortion is constant and affects all VLC 1.1.8 audio. True for all audio sources: internet stream, mp3, cd, flv, etc. Problem occurred on a clean install of Ubuntu 11.04 beta (32-bit) using only the included repositories, and updated as of today's date. Pulseaudio version: 1:0.9.22+stable-queue-24-g67d18-0ubuntu2 Disabling pulseaudio allows VLC to play cleanly. Have not observed audio distortion with other players using pulseaudio. Would like to see VLC operate properly with pulseaudio. I had no issues on same machine using Ubuntu 10.10 and VLC 1.1.4. ProblemType: Bug DistroRelease: Ubuntu 11.04 Package: pulseaudio 1:0.9.22+stable-queue-24-g67d18-0ubuntu2 ProcVersionSignature: Ubuntu 2.6.38-7.39-generic 2.6.38 Uname: Linux 2.6.38-7-generic i686 AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23. Architecture: i386 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/pcmC0D0p: blaine 2039 F...m vlc Card0.Amixer.info: Card hw:0 'Audigy2'/'SB Audigy 2 [SB0350b] (rev.4, serial:0x20061102) at 0xcc80, irq 19' Mixer name : 'SigmaTel STAC9750,51' Components : 'AC97a:83847650' Controls : 211 Simple ctrls : 46 Card1.Amixer.info: Card hw:1 'U0x46d0x8ca'/'USB Device 0x46d:0x8ca at usb-0000:00:1d.7-6, high speed' Mixer name : 'USB Mixer' Components : 'USB046d:08ca' Controls : 2 Simple ctrls : 1 Card1.Amixer.values: Simple mixer control 'Mic',0 Capabilities: cvolume cvolume-joined cswitch cswitch-joined penum Capture channels: Mono Limits: Capture 0 - 3072 Mono: Capture 0 [0%] [18.00dB] [off] Card2.Amixer.info: Card hw:2 'Generic'/'HD-Audio Generic at 0xefddc000 irq 43' Mixer name : 'ATI R6xx HDMI' Components : 'HDA:1002aa01,00aa0100,00100200' Controls : 4 Simple ctrls : 1 Card2.Amixer.values: Simple mixer control 'IEC958',0 Capabilities: pswitch pswitch-joined penum Playback channels: Mono Mono: Playback [on] Date: Tue Apr 5 06:32:13 2011 InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta i386 (20110330) ProcEnviron: LANGUAGE=en_US:en PATH=(custom, user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: pulseaudio UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 01/08/2007 dmi.bios.vendor: Dell Inc. dmi.bios.version: A07 dmi.board.name: 0HJ054 dmi.board.vendor: Dell Inc. dmi.chassis.type: 6 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA07:bd01/08/2007:svnDellInc.:pnDellDM051:pvr:rvnDellInc.:rn0HJ054:rvr:cvnDellInc.:ct6:cvr: dmi.product.name: Dell DM051 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/751265/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
