When my teacher gives a presentation in our class, it is recorded.
The end result is that you have an mp4 file with the slides and the voice of my teacher.
In most cases the first ten-15 minutes is just silence and the welcome slide.
My question is how do I remove or delete the silence from this mp4 using command line tools such as sox or ffmpeg, or in any programmatic way.
So that the long periods of silence are detected and then automatically removed and the new mp4 file contains only parts where the teacher is speaking.
For wav files I know one can use sox to remove silence like:
sox this.mp4 out6.mp4 silence -l 1 0.1 1% -1 2.0 1%