Ffmpeg

Skill cxcscmu/SkillLearnBench/skills/human_authored/video-object-counting/ffmpeg

Extract key frames (I-frames) from video files using FFmpeg command line tool. Use this skill when the user needs to pull out keyframes, thumbnails, or important frames from MP4, MKV, AVI, or other video formats for analysis, previews, or processing.From its SKILL.md

Install

npx -y skills add cxcscmu/SkillLearnBench --skill ffmpeg

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SKILL.md

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FFmpeg Keyframe Extraction

Extract key frames (I-frames) from video files using FFmpeg CLI.

Prerequisites

FFmpeg installed and available in PATH
Input video file (MP4, MKV, AVI, MOV, etc.)

Methods

Method 1: Select Filter (More Control)

ffmpeg -i <input_video> -vf "select='eq(pict_type,I)'" -vsync vfr <output_pattern>
Method 2: Skip Frame (Faster)

ffmpeg -skip_frame nokey -i <input_video> -vsync vfr <output_pattern>
Key Options
Option	Description
-i <file>	Input video file
-vf "select='eq(pict_type,I)'"	Filter selecting only I-frames
-skip_frame nokey	Skip decoding non-keyframes (performance)
-vsync vfr	Variable frame rate, prevents duplicates
-q:v <n>	Quality (1-31, lower = better, for JPEG)
-frame_pts 1	Use presentation timestamp in filename
Output Patterns
frame_%03d.png - PNG sequence (frame_001.png, frame_002.png...)
frame_%03d.jpg - JPEG sequence
frame_%d.bmp - BMP sequence
Examples
Basic PNG extraction:

ffmpeg -i video.mp4 -vf "select='eq(pict_type,I)'" -vsync vfr keyframe_%03d.png High-quality JPEG:

ffmpeg -i video.mp4 -skip_frame nokey -vsync vfr -q:v 2 keyframe_%03d.jpg With timestamps:

ffmpeg -i video.mp4 -vf "select='eq(pict_type,I)'" -vsync vfr -frame_pts 1 keyframe_%d.png


To specific directory:

ffmpeg -i video.mp4 -vf "select='eq(pict_type,I)'" -vsync vfr ./output/keyframe_%03d.png


## Notes
Method 2 (-skip_frame nokey) is faster as it skips decoding non-keyframes
Method 1 offers more filtering flexibility (can combine with other filters)
Keyframe frequency depends on video encoding settings
Use -vsync vfr to avoid duplicate frames in output

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.