Lip sync in 2025 is exactly the same as lip sync in 1999
No really, there is no fancy method or special tools needed. It's just the most basic of editing, and it works quite similarly to how the original animators did it.
Level 1: A scene where nothing is moving except a character's mouth
Anime typically only has 3 different positions for a mouth: Open, middle, and closed. So you just take those 3 frames, cut them to single frames, then you make copies of them and put them in an order that matches the sounds. That's it. With a little bit of practice it becomes fairly quick.
Level 2: A scene where the characters mouth is not moving around, but there is other stuff moving in the scene.
For these type of scenes, its very similar to the above, only you have to draw a mask around the mouth and overlay them on top of the scene. This lets you animate the mouth movement without effecting other things in the background of the scene.
Level 3: A highly animated scene where the character is moving all around.
In cases like this, you simply try to match it up to the sound as good as you can. Consider where to cut the clip and play around with shifting it forward and backward in time, speed changes, frame holds, whatever. Again, its just editing, but scenes like this can't always work wherever you want them to.
Hope that helps!
