manipulate video files using ffmpeg

video.sh

# extract good parts
ffmpeg -ss 00:00:00 -t 00:00:51 -i VID_20191216_000516.mp4 -vcodec copy -acodec copy 1.mp4
ffmpeg -ss 00:01:10 -i VID_20191216_000516.mp4 -vcodec copy -acodec copy 2.mp4
# convert for concat
ffmpeg -i 1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate1.ts
ffmpeg -i 2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate2.ts
# concatenate
ffmpeg -i "concat:intermediate1.ts|intermediate2.ts" -c copy -bsf:a aac_adtstoasc output.mp4
# rotate
ffmpeg -i output.mp4 -vf "transpose=1" rotated.mp4
# convert subtitles downloaded from youtube
pip install --user webvtt-py
python -c "import webvtt; webvtt.from_sbv('captions.sbv').save_as_srt()"
# hardcode subs
ffmpeg -i rotated.mp4 -vf subtitles=captions.srt out.mp4