ffmpeg
Table of Contents
1. Convert all audio to mp3
for i in *.webm; do ffmpeg -i "$i" "${i%.*}.mp3"; done
2. Extract clip from audio file
ffmpeg -i input-file.webm -ss 00:31:04 -to 00:31:45 -c copy clip-output.webm
3. Remove audio from video
ffmpeg -i $input_file -c copy -an $output_file
4. Add audio to image
image.jpg + music.mp3 = video.mp4
ffmpeg -loop 1 -i image.jpg -i music.mp3 -c:v libx264 -tune stillimage -c:a aac -b:a 192k -shortest -pix_fmt yuv420p video.mp4