[MEncoder-users] Audio Sync issues

[Rolf Ernst]

From: mencoder-users-bounces at mplayerhq.hu
[mailto:mencoder-users-bounces at mplayerhq.hu] On Behalf Of Jeff Cranmer
Sent: Thursday, September 15, 2011 8:11 PM
To: MEncoder usage discussions
Subject: Re: [MEncoder-users] Audio Sync issues

On Thu, 2011-09-15 at 20:13 -0400, Jeff Cranmer wrote:
> > >
> > > "C:\Bin\mencoder.exe" "E:\Rip\2011_9_13_14_7_47.TS" -o
> > "E:\Enc_Out\2011_9_13_14_7_47.avi"  -ovc x264 -x264encopts
> > threads=0:bframes=5:b-adapt=2:partitions=all:cabac:nopsnr:nossim:mix
> > ed_refs:frameref=6:weight_b:b_pyramid=normal:me=umh:merange=16:subme
> > =6:analyse=all:8x8dct=1:trellis=2:psy-rd=1,1:no-fast-pskip=1:crf=23
> > -oac copy -vf 
> > tinterlace=4,filmdint=io=30:24/fast=0,crop=1184:720:34:0
> > -noskip -fps 60000/1001 -ofps 24000/1001
> > 
> > I have done hundreds like this. Note
> > 
> > tinterlace=4,filmdint=io=30:24/fast=0
> > 
> > and
> > 
> > -noskip -fps 60000/1001 -ofps 24000/1001
> > 
> > The reason is that the PVR records at 59.94 and you want to reduce 
> > to 23.976. Tinterlace does a great job.
> > 
> > I have zip sync problems.
> > 
> > (Substitute the x264 options for your DivX settings, of course)
> > 
> > I do it all the time.
> > 
> Thanks Rolf
> 
> I'm trying these options now.  I'm getting quite a few '@@@@@@@@ 
> Bottom-first field??? @@@@@@@@' errors during the encode.  Can I 
> safely ignore these, or do I need to add another option to cure it?
> 
> Jeff
> 
> 
It's a lot closer, though the audio seems to be leading the video by a
small, but progressively increasing amount. 

Here's the revised command:
mencoder infile.mpg -noodml -ffourcc XVID -vf
scale=720:480,tinterlace=4,filmdint=io=30:24/fast=0 -aspect 16:9 -ovc lavc
-lavcopts
vcodec=mpeg4:threads=8:vbitrate=4000:cmp=2:subcmp=2:trell=yes:v4mv=yes:mbd=2
:aspect=16/9:top=0 -oac pcm -channels 2 -noskip -fps 60000/1001 -ofps
24000/1001 -o outfile.avi 

This may be related to Andrew's earlier suggested solution.  I'm going to
re-add the -vf harddup option and see if that cures the remaining sync
issues.

-----------------

One difference I notice is that you start out with an mpeg container. I have
always used the transport stream container (.TS) which might be something to
try. I doubt that the harddup will make a lot of difference.

One thing I notice is that you are converting to PCM. Any particular reason
why you are keeping the original audio? You are certainly not getting a
quality boost here - just a bigger file. The PVR captures either in AAC or
AC3, both lossy formats and doing an -oac copy will give you a smaller file
with equal quality. But maybe this is a limitation of your playback device?