Indexing scene changes for use with Aegisub's timing post-processor

[hamc09]

I hope I got the right sub-forum for this. I'd like to be able to use Aegisub's timing post-processor's keyframe snap functionality to make my life a little easier when timing my subs, but I find that whatever Aegisub uses to detect scene changes and set these keyframes works abysmally for at least what I work with, which is animation; tons and tons of false positives and missing lots of actual scene changes. I'm wondering if there's another program that would do this better and spit out its index as a list of frame numbers that could be loaded into Aegisub.

[sneaker]

Aegisub reads I frame positions from the source video so it all depends on how it was encoded.

To create better ones you can try e.g. x264:
x264 INPUT --preset ultrafast --keyint infinite --scenecut 40 --pass 1 -o NUL

Aegisub can read the log file from the first pass as a keyframe file. There might be other solutions using ffmpeg or AviSynth but I'm too lazy to look right now. Of course x264 encoding wastes time on some unnecessary things but the faster preset should keep that down. If the source has a high resolution it might even be worthwhile to downscale. If you plan on re-encoding anyways you should just do that before doing the subtitle work.

[hamc09]

That's actually super helpful, thank you! Any alternate methods you or anybody else digs up so I could make some comparisons would be great, but for now this works quite well. Many thanks!