notes/software/video_editing.md

Trimming

delete pieces before N-th second and after M-th second

mencoder -ss N -endpos M -oac copy -ovc copy in.mp4 -o out.mp4

Save 30 second starting from 2:30

ffmpeg -i in.mp4 -ss 2:30 -c copy -t 30 out.mp4

without audio

ffmpeg -i in.mp4 -ss 2:30 -c copy -an -t 30 out.mp4

Capture from the screen

ffmpeg -an -t 32 -f x11grab -s hd720 -i :0.0 -y -sameq out.mp4

Changing playback speed

mencoder -speed 0.2 -nosound -ovc copy -of lavf in.mp4 -o out.mp4

Rotation

mencoder -vf rotate=2:harddup -mc 0 -oac pcm -ovc lavc in.mp4 -o out.mp4

Rotation + cropping

mencoder -vf crop=720:720:230:0 -vf-add rotate=2:harddup -mc 0 -oac pcm -ovc lavc -lavcopts vbitrate=5000 in.mp4 -o out.mp4

Build video from images

ffmpeg -f image2 -r 2 -i demo%d.png -vcodec libx264 out.mp4

ffmpeg -y -f image2 -r 40 -i demo-%d.png -vcodec libx264 -vf 'crop=540:460:30:70,scale=540:trunc(ow/a/2)*2'  out.mp4

ffmpeg -y -loop 1 -t 10 -i image.png -vcodec libx264  out.mp4

Empty video (black screen)

ffmpeg -y -t 5 -s 1080x458 -f rawvideo -pix_fmt rgb24 -r 25 -i /dev/zero video-black.mp4

Overlay text

ffmpeg -y -i in.mp4 \
    -vf drawtext="fontfile=Font.ttf:textfile=text.txt:fontcolor=white:fontsize=30:x=(w-text_w)/2:y=(h-text_h)/2" \
    out.mp4

ffmpeg -y -i in.mp4 \
    -vf drawtext="fontfile=Font.ttf:text='some text':fontcolor=white:fontsize=100:x=(w-text_w)/2:y=(h-text_h)/2" \
    out.mp4

Tiled video

The first tile is padded, then the second video is overlayed over the empty part:

ffmpeg -y -i tile1.mp4 -i tile2.mp4 \
    -filter_complex '[0:v]pad=iw*2:ih:0:0[tmp1];[tmp1][1:v]overlay=W/2:0[vid]' \
    -map '[vid]' -c:v libx264 out.mp4

Concatenation

ffmpeg -y -i video1.mp4 -i video2.mp4 -i video3.mp4 \
    -filter_complex "[0:v] [1:v] concat[tmp1] ; [tmp1] [2:v] concat [vid]" -map '[vid]' -c:v libx264 out.mp4

ffmpeg -y -i video1.mp4 -i video2.mp4 -i video3.mp4 \
    -filter_complex " [0:v] [1:v] [2:v] concat=n=3 [vid] " -map '[vid]' -c:v libx264 -pix_fmt yuv420p out.mp4

Video with static image in background

ffmpeg  -loop 1 -i background.png -i video.mp4 \
    -filter_complex '[0:v][1:v]overlay=1300:150:shortest=1[vid]' -map '[vid]' \
    -c:v libx264 -y out.mp4

Take snapshots

Every 5 second:
ffmpeg -i in.mp4 -vf fps=1/5 out%d.jpg