[MEncoder-users] some minutes delay between audio and video

[Bill Crockett]

On 31/12/2011 9:04 AM, Malte Schünemann wrote:
> I am frequently converting videos coming via satellite as transport 
> stream. I recently experienced a strange delay between the audio and 
> the video part that is in the range of minutes.
>
> The problem happens only if I attempt to cut out advertisings - so far 
> I only observed the problem at the beginning of the file (cutting off 
> the first 5 minutes). I tried to overcome the problem with 
> -audio-delay, but had no success.
>
> My options are usually the following.
>
> -ofps 25 -hr-edl-seek -demuxer lavf -oac  lavc -ovc lavc -of mpeg
> -mpegopts format=dvd:tsaf -vf scale=720:576,harddup
> -srate 48000 -af volnorm=2:0.15:lavcresample=48000 -lavcopts 
> vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=9800:keyint=25:vstrict=0:acodec=ac3:abitrate=192
> -ofps 25 -edl file.edl -o video.mpg video.ts
>
> Thanks
>   Malte
> _______________________________________________
>

I changed a few parameters to suit my test video "videoTS.mpg" which is 
an MPEG-TS

mencoder -fps 25 -oac lavc -ovc lavc -of lavf -lavfopts format=mpg -vf 
crop=512:560:102:8,harddup -lavcopts 
vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=8000:vbitrate=4854:keyint=25:vstrict=0:acodec= 
/
mp2:abitrate=192:autoaspect -delay 0.125 -ofps 25 -o video.mpg videoTS.mpg

I did not use Edit Decision List options because I'm only trying to get 
the A/V  in sync.  I found using -demuxer lavf printed out a lot of 
errors.  Also, -of mpeg caused many errors (I don't know why), so I 
changed it to -of lavf.  -vf crop is for my video for testing.  I 
dropped the -srate and -af as I did not need them.  vbitrate  and 
maxrate are for my taste.  acodec=ac3 caused a problem, so changed to mp2.

-audio-delay only works with -of avi.  If you are using a different 
muxer, then you must use -delay instead.  Delay relative to video: 
-125ms was retrieved via MediInfo from the videoTS.mpg file.  I could 
not find this info via MPlayer or FFprobe.  After the encode, the A/V in 
video.mpg was in sync.  Without -delay, it was up to 300 ms out.