Opened 7 years ago

Closed 14 months ago

#12027 closed Bug Report - General (Abandoned)

A/V sync problem

Reported by: mythtv@… Owned by:
Priority: minor Milestone: unknown
Component: MythTV - General Version: 0.27-fixes
Severity: medium Keywords:
Cc: Ticket locked: no


Audio plays ~2 seconds ahead of video.

Recording plays fine in VLC, etc.

My network has 3 myth boxes, a backend with a HDPVR and a 2250, and two frontends. Backend and one frontend are slackware with myth compiled from source by slackbuild system (0.27-fixes). The other frontend is mythbuntu upgraded (and current) using the 0.27 repo.

Problem happens on both frontends. Many configuration options have been tested, none fixed the problem: HDMI audio vs. stereo line out, vdpau vs. software decode, vdpau vs. other overlays, upscaling or not, etc.

Problem happens during liveTV and recordings, but not all. Problem happens on both capture devices, but not all of the time. Problem only seems to happen with AC3 audio, but not all AC3.

Exact amount of video delay seems variable, but usually in the 1.6 to 2.4 second range. Because of this, and because it only happens on some recordings, manual adjustment of the audio sync parameter is not a useable workaround.

Sample file (hope it works, I'm new to dropbox.) :

Sample is the first 200 MB of a capture from the HDPVR. I'll dig around and see if I can find a capture from the 2250 showing the same problem.

Change History (3)

comment:2 Changed 6 years ago by charles.bovy@…

I'm seeing this too, after I migrated from one frontend (non NVIDIA) to another frontend (NVIDIA). Unfortunately I'm able to pinpoint the cause:

  • Not all recordings are having the issue
  • It looks like it is related to VDPAU. Tried different versions, but disabling VDPAU gives best results.
  • Also using a Zotac. In this case Zotac ID42, with GT610.

comment:3 Changed 14 months ago by Mark Kendall

Resolution: Abandoned
Status: newclosed

After 6 years, much has changed in the MythTV code and there is an entirely new A/V sync method - which appears to be working without issue on master and 0.31. If the problem persists, please open a new ticket.

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