free tools that can do splitscreens of existing videos?

[muffinman123]

so right now I have 2 videos of the same event taken from 2 different perspectives. the videos are the same dimension and same codec and everything.

I want to combine these 2 videos into a single video with top half being 1 perspective and the bottom half being the other.

the video lengths are not the same because one recorded longer than the other guy, and I can't trim without reencoding because of the keyframes.

originally I used pip+ video effects for windows movie maker. even though the video lengths are different as I said before, I can easily manually adjust the overlap so I don't have to trim the videos beforehand. however pip+ only gives 2 week trial period and it's way past that now (I suppose I could try and edit the registry and see if I can reset the trial period, but I can't find any info on how to do it).

now I have read before that avisynth can do splitscreen, but it's script without a UI to adjust the overlap, so this means I will have to trim and reencode my video 1 time and then split screen and recode a 2nd time. I'd like to avoid losing quality like this.

[racer-x]

AviUtl is free and can do it easily if you are a good learner.........

Here is a splitscreen example I posted in another thread: https://forum.videohelp.com/attachments/22860-1390138081/SloMo_Comparison2.mp4

[poisondeathray]

now I have read before that avisynth can do splitscreen, but it's script without a UI to adjust the overlap, so this means I will have to trim and reencode my video 1 time and then split screen and recode a 2nd time. I'd like to avoid losing quality like this.

You just re-encode it once. You preview & adjust the script before encoding

In fact, you don't even have to re-encode , you can just "play" the script

[Budman1]

There are many players that will play the AVISynth script, as Poisondeathray suggested using, and when you get it correct, you can send that to you favorite editor/converter that supports AVISynth and Encode it One time. My personal choices are FFMpeg and Virtualdub, both of which can accept AVS files and add additional filters if you wish.