Is it possible to fix a sync issue on a converted file (mp4)

[AndyD]

s a concert and unfortunately the audio is never in sync. Is it possible for me to fix?

[PuzZLeR]

Yes: If it's a linear shift (the same +/- delay throughout) use mp4box with the -delay command.

Maybe: If it's not a linear shift throughout, you'd need to demux the audio and re-encode it with a different speed, and remux it back (and hope it works). If that still doesn't provide sync, then it's surgery - you'd need to partition it, the smaller segments the better, and adjust one-by-one.

[AndyD]

It's pretty much off by 2 seconds for the entire vid but mp4box doesn't seem to be helping. Or I just don't know how to set the command properly adjust the video for the audio lag.

Is there another tool I can use that would allow for more precision and with a gui?

[t0nee1]

Try with AviDemux, use the audio Shift(ms) tool to line up, preview/play, and if it syncs, save a new mp4.....Good luck!..