Aligning movie over-dubbing with original audio track


can someone please help me? I’m rather beginner…

I want to add second audio track into my mkv. It is different language over-dub. I thought the task will be pretty simple. I knew the movie file is in 23,976fps and the audio I want put on is probably 25fps. However after stretching the track by -4.096% they didn’t align. After trying some values, I found out it is somewhere around 4.08% . Which is weird.

So I managed to manually align 2 points of the tracks - near the very beginning and the end. However it turned out that they didn’t align in some places in the middle. There are probably tiny differences between cuts in the source file and the over-dub track. Which messes with the whole alignment.

So I’m at my wit’s end. Right now I will have to manually align all scenes to match. So I wonder…

Isn’t there any plugin, which would automatically align+stretch in/out two tracks based on the curve. Even when there are differences (voices are obviously different, but background is the same). Would spare me a ton of work.

Thanks for answer.

based on the curve.

What curve? If you have work that wanders in duration, there is no goal to program to.

Yes, you may have to do it scene by scene, but Effect > Change Speed has provision to put times into the tool, and Audacity will tell you start, stop and durations. So it’s not impossible.

Changing existing products around to make a new product is not for the easily frightened. You haven’t bumped into compression damage, yet.

Each time you re-issue a finished product with changes, you have to produce it in near-original compressed format. Audacity doesn’t edit compressed materials. It uncompresses the work to original format, makes changes and then makes a new compressed product when it’s done. Each compression pass increases the sound damage.

Did you run out of room? If you edit a highly compressed video, the tiny, convenient sound files vanish in favor of massive, uncompressed sound files and Audacity has to deal with that. Some of the correction tools work entirely in memory, so there’s no hard drive to fall back on.

If you install FFMpeg, Audacity will open many “foreign” sound formats including videos, but you need a video editor to smash it all back together after you make the new track.


The quality of the over-dub isn’t spectacular so compression damage is my least problem.

Curve of the reference audio

There’s only one tool I know of which will allow you to change the action of the correction in the middle of the correction.

And it’s not a curve. It’s a ramp. Start here and end here. There are no variables in the middle.