video-frame-extraction

Video Frame Extraction with FFmpeg

Extract I-frames (keyframes) from a video file and save them as sequentially numbered PNG images.

Command

ffmpeg -i <input_video> -vf "select=eq(pict_type\,I)" -vsync vfr <output_dir>/keyframes_%03d.png

• select=eq(pict_type\,I) — selects only I-frames (intra-coded keyframes)
• -vsync vfr — variable frame rate output to avoid duplicates
• %03d — zero-padded 3-digit index starting at 1 (e.g., 001, 002, ...)

Example

ffmpeg -i /root/super-mario.mp4 -vf "select=eq(pict_type\,I)" -vsync vfr /root/keyframes_%03d.png

Output files: /root/keyframes_001.png, /root/keyframes_002.png, etc.

Listing Extracted Frames

After extraction, list frames sorted by name to get timeline order:

import glob, os
frames = sorted(glob.glob('/root/keyframes_*.png'))

Notes

• I-frames are the most information-rich frames and good representatives for scene analysis.
• Frame indices start at 1, not 0.
• If the video has no explicit I-frames, use -vf fps=1 to extract one frame per second instead.