| name | video-keyframe-extraction |
| description | Use this skill to extract keyframes (I-frames) from an MP4 video file using ffmpeg. This produces numbered PNG files in a specified output directory. |
How to extract keyframes from a video
Use ffmpeg to extract only I-frames (keyframes) from the video:
ffmpeg -i /root/super-mario.mp4 -vf "select=eq(pict_type\,I)" -vsync vfp /root/keyframes_%03d.png -y
This will produce files like /root/keyframes_001.png, /root/keyframes_002.png, etc.
Verifying extraction
After extraction, list the files to confirm how many keyframes were produced:
ls -1 /root/keyframes_*.png | sort
Count them:
ls -1 /root/keyframes_*.png | wc -l
Important notes
- The output format
keyframes_%03d.png is zero-padded to 3 digits, starting from 001.
- ffmpeg numbers sequentially starting at 1.
- All keyframes are in timeline order by default.
- If the number of keyframes seems wrong, you can also try extracting at a fixed interval (e.g., 1 fps) using
-vf fps=1 instead, but I-frame extraction is the standard approach for "key frames."
- Use
ffprobe to check total number of I-frames beforehand if needed:
ffprobe -select_streams v -show_frames -show_entries frame=pict_type /root/super-mario.mp4 2>/dev/null | grep "pict_type=I" | wc -l
