Join .MP4 with .AC3 to .MKV without loss of sync

[vanleeuwen]

HI, I have looked every where for an answer but with no luck so here is my question:

I have a .mp4 and a .ac3 file. I can use media player classic to play them together using open file and the dub option for the .ac3 then seleting it as the play back stream.

I want to join these to one file. I used gdsmux to do it and got a .mkv file (as i wanted) but the audio loses sync (getting worse as the movie goes on). Any idea why this would be ? or am i doing something wrong ?

So playing in Media Player Classic - No loss of sync
Convert to .mkv with gdsmux - Out of sync getting worse the longer the move goes on.

Thanks

[Inspector.Gadget]

If the files play in sync in Media Player Classic when separate, then the delay of the audio is zero either way. GDSMux is buggy; you will have better luck using MMG (MKVMergeGUI) from the mkvtoolnix package. Be sure to set either a display frame size or aspect ratio in the GUI if your source MP4 file is anamorphic.

[vanleeuwen]

Thanks that worked Perfect !