vidpickr

Glossary · workflow

What is FFmpeg?

FFmpeg is the open-source command-line tool that handles essentially all video / audio processing on the internet. Encoding, decoding, muxing, demuxing, format conversion, streaming, filtering — it does all of it. YouTube's upload pipeline, every video editor's codec layer, every CDN's transcoding, every downloader's muxer either is FFmpeg or wraps FFmpeg.

Also called:ffmpeg cli · ffmpeg.org

FFmpeg is the standard answer to "I have a video file and need to do something with it". It supports nearly every codec ever shipped, every container format in use, every protocol that carries video. The CLI is famously dense ("ffmpeg -i in.mp4 -c copy out.mkv" copies; "ffmpeg -i in.mp4 -vf scale=1280:720 -c:a copy out.mp4" rescales while preserving audio).

For YouTube downloaders specifically: yt-dlp's final mux step shells out to FFmpeg. Server-side processing (our /clip endpoint, for instance) invokes FFmpeg directly. Browser-side muxing in VidPickr uses mp4-muxer.js which implements FFmpeg-equivalent muxing logic in JavaScript so we don't need to shell out at all.

Worth knowing: FFmpeg is LGPL/GPL, free for commercial use. Most "AI video tools" you see launching wrap FFmpeg with a GUI and charge for the convenience. The underlying capability has been free for 20 years.

Common questions

Is FFmpeg legal to use commercially?
Yes. LGPL build (linkable) is unambiguously legal for commercial use. GPL build (statically compiled with GPL-only codecs) requires the application to be GPL too — most commercial users pick the LGPL build.
Does FFmpeg work in the browser?
Yes — via ffmpeg.wasm, the WebAssembly port. Slower than native (~3-5× slower) but enables fully client-side video processing without a backend. Used by some online video editors.

Related terms

Mux (muxing)

Muxing is the process of combining separate audio and video streams into a single container file (MP4, MKV, WebM).

Codec

A codec is the algorithm that encodes (compresses) and decodes raw audio or video into a smaller stream.

Transcoding

Transcoding is the process of decoding a compressed media file and re-encoding it into a different codec, container, bitrate, or resolution.

VidPickr is a free, browser-based YouTube downloader. Every term in this glossary either describes how YouTube delivers video or why your downloads behave the way they do. Try the downloader →