[mythtv-users] losing audio/video sync when transcoding: a workaround

Peter Schachte schachte at csse.unimelb.edu.au
Mon Sep 18 06:23:02 UTC 2006


I've seen this issue discussed a number of times here, so I know
others have had this problem.  I post this workaround in the hope
it'll help others with this problem.

I often use nuvexport (thanks xris!) to cut commercials from movies
recorded off air (using a DVB-T tuner card) and save them into my
MythVideo collection.  Unfortunately, whenever my electric garage door
opener goes up, it generates 20 or so seconds of interference that
plays havoc with my recordings.  If I try to nuvexport a recording
that has such interference, I find that the audio and video in the
generated .avi file are hopelessly out of sync after the interference.

The solution I found is pretty simple:  edit out the interference as
if it were a commercial.  With the interference edited out, nuvexport
doesn't lose a/v sync, and the produced files are fine.

One small catch is that myth's commercial editor doesn't want to let
you put cut points too close together.  As I just mentioned in another
thread (MythArchive: Use cutpoints as chapter markers?), I've found
that you can do it, though, but putting the first cut point way too
early (I think 30 seconds or so is about right), then move forward say
10 seconds, hit enter, and choose the "move cut point to this
position" menu item.  Keep doing this until you get it where you want
it.  I found that 1) I couldn't just move it where I wanted in one go,
as it would tend to move the other cut point; and 2) it works better
to put the end cut point where you want and slide the start cut point
into place than the opposite.

I hope this helps.  Now, does anyone have any idea how to stop the
garage door opener from generating interference?  I've done some
googling, but can't find any suggestions short of replacing all my
antenna wiring.

Peter Schachte              Find a job you love, and you will never have to
schachte at cs.mu.OZ.AU        work a day in your life.
www.cs.mu.oz.au/~schachte/      -- Albert Einstein 
Phone: +61 3 8344 1338      

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