Audio sync problem streaming ubuntu 10.10 VLC 1.1.4
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
VLC media player |
Fix Released
|
Unknown
|
|||
vlc (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned |
Bug Description
The audio-sync function does not appear to work correctly in VLC 1.1.4 Ubuntu 10.10 Maverick.
[Symptom]
After initial audio/video sync up using audio-desync, the audio/video sync drifts out noticably within a few minutes and significantly in an hour or so.
* The standard Ubuntu Lucid 10.04 VLC 1.0.6 version performs correctly
* The MS windows (XP) version 1.1.4 performs correctly
[Test case]
A. Setup
* Same Hardware and software setup in both Ubuntu test cases
* Video in: PCI analog capture card (bt878video pci capture card, Hauppauge VCB Impact)
* Audio in: Soundcard line-in
* Std desktop install Ubuntu versions using Std default repos
* +VLC, +ffmpeg libavdevice-
* Broadcast TV analog out used as test input source. Video into capture card, audio into sound card ( I would usually be using analogue camera and mic/line in)
B. Procedure
1. Open GUI, test video/audio capture, by "Open Capture device" - Play
2. Select Streaming from menu, select Capture device tab, all input settings left at default
3. select Stream, Next, Next , Paste output string into textbox, as follows
--sout-keep --audio-desync=-40 :sout=#
* Audio-desync value adjusted to initial optimum value (predetermined before test)
* Width and height set to low values to minimise cpu load
* Same procedure in all cases including Win XP. Win test using similar hardware, bt878 pci capture card.
[Appendix]
Suspected that pulseaudio may be the cause:
* Removed pulseaudio and installed alsa mixer. Problem persisted.
* Also tried VLC 1.1.5 from Maverick Bleed PPA. Problem persisted
* Also tried VLC 1.1.4 from Lucid Bleed PPA with Lucid. Problem here as well.
Reported problem to Videolan Trac
Response as follows.
Changes (by courmisch):
* status: new => closed
* resolution: => incomplete
* component: I don't know => Access
Comment: And I bet you get the same effect if you just render the inputs locally,no? Then I would tend to blame the V4L2 and ALSA input plugins for not timestamping correctly. Or it might even be a driver bug.
Ticket URL: http://
I did not see the problem when playing capture device, only when streaming.
ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: vlc 1.1.4-1ubuntu1.1
ProcVersionSign
Uname: Linux 2.6.35-23-generic i686
NonfreeKernelMo
Architecture: i386
Date: Mon Dec 6 23:18:34 2010
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
ProcEnviron:
LANG=en_GB.utf8
SHELL=/bin/bash
SourcePackage: vlc
Changed in vlc: | |
importance: | Unknown → Undecided |
status: | Unknown → New |
status: | New → Incomplete |
Changed in vlc: | |
importance: | Undecided → Unknown |
status: | Invalid → Unknown |
Changed in vlc: | |
importance: | Unknown → Undecided |
status: | Unknown → New |
status: | New → Incomplete |
description: | updated |
Changed in vlc: | |
importance: | Undecided → Unknown |
status: | Incomplete → Unknown |
Changed in vlc: | |
status: | Unknown → Fix Released |
Update/further info
If package x264 is removed leaving only libx264-98, the audio-desync=xx necessary for initial sync reduces to zero or one frame or so. The audio-sync drift also is much less, but still quite apparent. Noticable in an hour or two and significant beyond 3 hrs plus, getting worse over time.
The Lucid test case had both x264 and libx264-95 installed. The Lucid test case was over a 6.5hr period with some minor flucuations in sync (est a frame or two at random test times) but was still well syncronised at the end of the test period.