handbrake automatically trimmed a video file

[cns00]

the input file was a .mkv file and it's length was 2h 7m 11s. in the beginning of the movie there was a black screen for 2s and then the movie started

i converted the file to a .mp4 file. i noticed that length of the converted movie file was 2h 7m 10s

i compared both files. i noticed that in the beginning of the converted movie file there was a black screen for 1s and then the movie started

i didn't tell handbrake to cut 1s from the black screen and it did that on its own. can it do that? it didn't do that for the other converted movie files and the length was the same as the input file

[LigH.de]

Only a guess: In your original file, the audio stream may have started at the beginning, but the video stream had to be delayed to be in sync with it. This may happen when there was a trailer video (e.g. FBI warning screen) before the start of the main movie, but the audio stream was extracted not from the movie's own start offset, but spanning both.

Handbrake will possibly have started the conversion at the start of the video track, so you lost the prepending bit of the audio stream. Which was possibly silent anyway...