[MEncoder-users] Audio Sync issues

[Rolf Ernst]

On Fri, Sep 16, 2011 at 1:45 PM, Jeff Cranmer <jeff at lotussevencars.com>wrote:

> -mc 0 didn't seem to help.
> Perhaps I'm misunderstanding this, but wouldn't we want to set the
> number to something else other than 0, to allow the program to A-V sync
> sucessfully?
>
> On Fri, 2011-09-16 at 09:35 -0400, Jeff Cranmer wrote:
> > > About the -noskip option:  maximum A-V sync correction per frame (in
> > > seconds) -mc 0 should always be combined with -noskip for mencoder,
> > > otherwise it will almost certainly cause A-V desync.  I don't know if
> > > that will help.  All you can do is try it.
> > >
> > > Bill
>
> Jeff,

what he says is correct - normally you want to set it to 0 which means
'don't deviate at all from the a/v sync'. That being said - I have never
used it with the PVR encodes, not sure whether it would be of benefit or
detriment - I just don't have any sync issues. I will give it a try using
-oac pcm and see whether this might play into it.

Part of the problem could be that I don't think pcm has timecodes built into
it, just x number of samples/sec whereas if you copy the AC3 stream that has
timecodes. This becomes important as there are occasional 'glitches' in the
recordings that the PVR makes. It's really of no big importance as the
playback can always recover because of the timecodes for both the audio and
video stream. (Look months back in this list and you will see how I brought
it up before). Since the pcm does not carry timecode information the
occasional glitch might throw it off, just a hypothesis. Just for grins I
would suggest to do an -oac copy and see whether this solves the problem. At
least you will know where to look then.