[MEncoder-users] A/V sync challenges on h.264 transcoding, especially with edited files

[James Hastings-Trew]

Steve Mushero wrote:
> Hi - We are testing transacoding thousands of video streams to h.265/mp4
> for web downloading and are having A/V sync issues no matter how we do
> it.  The main challenge seems to be in source files that have been
> edited to add an advertisement or split for length - the extracted video
> & audio streams are different length even before we transcode to
> h.264/AAC.  But if we transcode to FLV or AVI (which we've done millions
> of times) they play just fine, but in MP4 they are out of sync as much
> as 50% of the time.  Is there something different in the mp4 container
> that makes it more sensitive to these sync issues or timing than FLV or
> AVI ?
>   
You didn't provide your mencoder command line (or if you did, I missed 
it) but just tossing this out there... is harddup the last option in 
your -vf chain? If not, try adding it and see if your sync problems go away.