Perform various data analysis on SEC 13-F and obtain some insights of fund activities such as number of holdings, AUM, and change of holdings between two quarters.
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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.
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查看安装方法安装前可以查看交给 AI 代理的指令内容。
Extract key frames (I-frames) from video files using FFmpeg CLI.
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
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Perform various data analysis on SEC 13-F and obtain some insights of fund activities such as number of holdings, AUM, and change of holdings between two quarters.
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AC branch pi-model power flow equations (P/Q and |S|) with transformer tap ratio and phase shift, matching `acopf-math-model.md` and MATPOWER branch fields. Use when computing branch flows in either direction, aggregating bus injections for nodal balance, checking MVA (rateA) limits, computing branch loading %, or debugging sign/units issues in AC power flow.
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Redact text from PDF documents for blind review anonymization
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Use when checking simplified ADA-derived plan-view bathroom accessibility constraints such as turning space, door clear width, toilet centerline, grab bars, and lavatory knee/toe clearance.
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Analyze failed GitHub Action jobs for a pull request.
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Use when extracting plan-view architectural geometry from DXF files with semantic CAD layers, especially when outputs must normalize rooms, doors, fixtures, clearances, and grab bars into machine-checkable JSON.
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