Fastest method to add .ass (ssa, aegisub) SubStationAlpha subs to mp4?

[mateuszn0]

So i have video file mp4, and without changing its quality i want to add ass hardsubs. i am doin this with ffmpeg: on windows:

ffmpeg -i input.mp4 -c:v libx264 -preset:v medium -profile:v baseline -level 3.0 -movflags +faststart -vf ass=insubs.ass -bufsize 4000k -qp 27 result.mp4

But it takes long time, or quality is bad. It have to be most compatible, so baseline, and good for web.

How to do it faster? When i change preset to ultrafast quality is very very bad.

I dont want to use mkvtoolnix and handbrake or avisynth. And it has to be on Windows. It has to be something, possible to do with one simple bat file, very fast, good quality,small size, just like original mp4 only with subs hardcoded. Thanks.

[Baldrick]

You can't add hardsubs without changing quality.

But you can try handbrakecli (command line version of handbrake) and see if you get faster encoding. But don't ask me how the command looks like.

Or get a FASTER computer.

[El Heggunte]

-qp 27? IMHO, you should be using --crf 21 OR LESS.

Also, please define "good for web". If that means "small filesizes", then at least resize to a lower resolution or/and apply some filtering, otherwise the reencode surely will lack too much quality.