ffmpeg.txt

sudo apt update
sudo apt install ffmpeg


merge audio & video
ffmpeg -i video.mp4 -i audio.wav -map 0:v -map 1:a -c:v copy -shortest output.mp4
https://stackoverflow.com/a/11783474/2437224

merge videos:
mylist.txt:
file '/path/to/file1'
file '/path/to/file2'

ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4

https://stackoverflow.com/a/11175851/2437224

https://video.stackexchange.com/questions/12905/repeat-loop-input-video-with-ffmpeg

Repeat video:
ffmpeg -stream_loop -1 -i input.mp4 -c copy output.mp4
// https://video.stackexchange.com/a/17389


hardcode sub:
ffmpeg -i mymovie.mp4 -vf subtitles=subtitles.srt mysubtitledmovie.mp4

ffmpeg -i video.mp4 -vf "subtitles=subtitles.srt:force_style='Alignment=10,Fontsize=24,PrimaryColour=&H0000ff&'" -c:a copy output.mp4

With fontName:
ffmpeg -i k2.mp4 -lavfi "subtitles=subtitles.srt:force_style='FontName=Noto Sans,Alignment=0,OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18,MarginL=5,MarginV=25'" -crf 1 -c:a copy "output.mp4"

without fontname
ffmpeg -i k2.mp4 -lavfi "subtitles=subtitles.srt:force_style='Alignment=2,OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18,MarginL=0,MarginV=60'" -crf 1 -c:a copy "output.mp4"

https://stackoverflow.com/questions/8672809/use-ffmpeg-to-add-text-subtitles

https://stackoverflow.com/questions/21363334/how-to-add-font-size-in-subtitles-in-ffmpeg-video-filter

https://stackoverflow.com/questions/57869367/ffmpeg-subtitles-alignment-and-position

giving fontfile:
fontfile=/Windows/Fonts/arial.ttf , instead of fontname

https://stackoverflow.com/questions/8103808/ffmpeg-drawtext-could-not-load-fontface-from-file


reduce video size:
ffmpeg -i input.avi -vcodec libx264 -crf 24 output.avi

https://unix.stackexchange.com/a/38380