video-ffmpeg
Skill0 starsChanged 35 days agoMITView on GitHub
Tested ffmpeg recipes for everyday video and audio jobs - trim, concatenate mixed formats, speed up or slow down with pitch-correct audio, crop/scale/pad, compress to a target file size, convert and remux, high-quality GIFs, extract audio or frames, background music that ducks under speech, picture-in-picture, watermarks, loudness normalization, phone footage (VFR) fixes. Use for any one-off ffmpeg task, or when the user asks to compress, convert, resize, speed up, make a GIF, add music, overlay a logo or webcam.
In this repository4 other files it gives its agents.
- video-captionsSkill
- video-cleanupSkill
- video-editSkill
- video-shortsSkill
The file
We split this skill into the rules it gives an agent
1 rule. About 0 are common, 0 are distinctive, and 1 is very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈0
Distinctive · estimate
This author's own choices. Worth a look.
1
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Very specific: line 18
Never write over an input file.
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
video-ffmpeg
Find the recipe in references/recipes.md, copy the command, change only the file names and the documented knobs. Every command there runs in CI against generated clips.
Rules
- Never write over an input file; new name in the same folder (or
edits/). - Probe first when the input is unknown:
uv run ../video-edit/scripts/probe.py INPUT. - Re-encode when cutting precisely;
-c copyonly for remuxing or rough keyframe cuts. -pix_fmt yuv420pand-movflags +faststartfor anything that must play everywhere.- On Windows, filter arguments with paths (subtitles, fonts) need the drive colon escaped
(
C\:/path); simpler to run ffmpeg from the file's folder and use a bare name.
Helper scripts (the error-prone ones)
- Fit a size limit:
uv run scripts/compress.py INPUT --mb 25 [--max-height 720](two-pass, computes bitrate from duration, downscales when the bitrate is too low). - Music under speech:
uv run scripts/duck.py VIDEO MUSIC [--music-db -14] [--duck 8](loops/fades music to the video length, sidechain-compresses it under the voice).
Index
| task | section |
| frame-accurate or instant trim | Trim |
| join clips, same or mixed formats | Concatenate (many clips: video-edit EDL) |
| 1.5x / 0.5x with normal-pitch audio | Speed change |
| 720p, square, letterbox, vertical with blur | Crop, scale, pad |
| CRF quality, HEVC, target size | Compress |
| remux, MOV/ProRes to MP4, WebM | Convert and remux |
| GIF with palette | GIF |
| m4a/mp3/wav, frame grab, contact sheet | Extract audio, frames |
| sidechain ducking | Music under speech |
| webcam overlay | Picture-in-picture |
| logo overlay | Watermark |
| EBU R128 | Loudness |
| VFR to CFR, rotation | Phone footage |
Tasks that cut by content (remove pauses, fillers, sections by transcript) belong to
video-edit / video-cleanup; captions to video-captions; vertical face-tracked clips to
video-shorts.
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