synchronizing video and audio in a remuxed MKV
Use mkvmerge with
  -y or --sync 

                       Synchronize, adjust the track's timecodes with

                       the id TID by 'd' ms.

                       'o/p': Adjust the timecodes by multiplying with

                       'o/p' to fix linear drifts. 'p' defaults to

                       1 if omitted. Both 'o' and 'p' can be

                       floating point numbers.