Why the subtitles aren't going away instantly?

[cns00]

I have a Chinese movie which has Chinese writing in the movie in some scenes. I am making an srt file for the movie so I can have English subtitles for the Chinese writing.

I am using Aegisub to make the srt file. I am playing the scenes that have Chinese writing in Aegisub frame by frame. I am setting the start time of each subtitle line to be the first frame which shows the Chinese writing and I am setting the end time of each subtitle line to be the last frame which shows the Chinese writing. The next frame after that scene has no Chinese writing.

The problem is that when I play the movie in PotPlayer the subtitle line is still showing in the next frame which has no Chinese writing and then it instantly goes away. It looks like the end time of the subtitle line is a bit late. I have to set the end time of a subtitle line in Aegisub to be like 5 or 6 frames before the Chinese writing goes away. Now when I play the movie the subtitle line is going away before the next frame which has no Chinese writing shows. Thus I have to decrease the end time of the lines by 100ms. If the end time is 0:01:22.39 then I am making it 0:01:22.29.

I want to ask why is the subtitle line still showing in the next frame which has no Chinese writing if I set the end time of the subtitle line to be the last frame which shows the Chinese writing?

[ProWo]

Maybe there is a video offset.
Check this with this commandline:

ffmpeg -i "fullpath_yourinputvideo"

There is a info line saying g.e. start: 0.000000
If this start info isn't 0.000000 there is a video delay.

[cns00]

I did what you said. I can't see any start time.