need help with .ASS subtitle

[HDNoob]

Hi, I just extracted an .ASS Sub from an MKV H264 video. I converted the video to MP4 AVC but now sub with it I want to implement the sub into my MP4 AVC video.
How can I do that?

[check]

You can't use ASS in mp4, you need to convert to an MP4 compatible format, like SRT or TTXT. Try aegisub for the former.