ffmpeg cut video by time upto milliseconds

I really don't want to bother me with re-encoding (which is an use of FFmpeg I don't master on command line). So is there a way to get the closest (P- or B-) frame, doing some calculations with the preceding I-frame to generate a new I-frame, then start the video with this brand new I-frame and no sound, until the correct timestamp is reached. I know I'm probably trying to cut my video neither on a I-frame, nor on P- or B-frames. I'm aware that the position of the -ss option in the command line matters: here, it is supposed to give me all the accuracy FFmpeg can offer. Here is my ffmpeg command line : ffmpeg -i video.mp4 -ss 0:0:0.9 -vcodec copy -acodec copy videoB.mp4 -y So you are telling to ffmpeg 'give me the final 50 seconds from 150 seconds of the input' if this don't work, maybe you'll need write in a verbose way: -vf 'trimstart100:duration50'.

I think the precise moment is between two keyframes, because whatever the timestamp I try to cut at, I always get too much sound (and video) or too few. So it is possible to set just the end values to keep everything before the specified time. I'm trying to cut a video (a debate on TV) with FFmpeg without re-encoding, and I need to cut between 2 sentences a guy pronounce.

Ffmpeg cut video by time upto milliseconds