ffmpeg-cli_skill

Overview

This skill is an FFmpeg CLI reference and practical command cookbook for video and audio processing. It focuses on format conversion, filtering, trimming, encoding, and media automation with opinionated, battle-tested command patterns. Use it to build reliable one-liners or complex filter_graph workflows for thumbnails, GIFs, slideshows, overlays, and hardware-accelerated encodes.

How this skill works

The skill documents common ffmpeg and ffprobe flags, filter names, stream selectors, and mapping patterns, plus examples for remuxing, scaling, padding, trimming, and complex filter graphs. It explains when to copy streams (-c copy) versus re-encoding, how to use -filter_complex for multi-output workflows, and how to inspect files with ffprobe for verification and faststart checks. Reference sections link to deeper guides for encoding settings, audio processing, and asset generation.

When to use it

• Convert containers without re-encoding (remux) or re-encode to a different codec/container.
• Resize, pad, crop, or change pixel aspect (scale, pad, setsar).
• Trim video by time or build concatenated sequences with accurate seeking.
• Overlay logos, burn subtitles, add text, or run complex filter graphs with filter_complex.
• Generate GIFs, thumbnails, storyboards, slideshows, or animated exports.
• Optimize encoding with CRF/bitrate settings or enable GPU acceleration.

Best practices

• Prefer -c copy for fast remuxing when codec/container are compatible to avoid quality loss.
• Use filter_complex and named pads for multi-output workflows to avoid duplicated decoding.
• Set setsar=1:1 and format=yuv420p for consistent playback across devices.
• Test trims both with input (-ss before -i) and output seeking for speed vs accuracy trade-offs.
• Keep dimensions divisible by 2 (use scale h=-2) to prevent encoder errors on many codecs.

Example use cases

• Remux MP4 to MKV without re-encoding: keep original quality and speed up processing.
• Create two scaled outputs (16:9 and vertical shorts) from one input with a single ffmpeg call using split and overlay.
• Trim a clip from 00:00:10 to 00:00:25 and re-encode or fast-cut with -c copy depending on keyframe alignment.
• Burn subtitles or overlay drawtext for captions and branding on exported videos.
• Generate thumbnails and storyboards by extracting Nth frames or keyframes with ffprobe-assisted selection.