Does this run ffmpeg for me?

Yes — add your video, audio or image in the Run panel and the command executes in your browser with ffmpeg.wasm, then you download the output. You can also copy the command for your own terminal.

What CRF value should I use?

18 is close to visually lossless, 23 is the balanced default, and 28 gives clearly smaller files with some quality loss.

Which preset is best?

Slower presets compress better at the same quality. Use medium for everyday work and veryslow when file size matters more than time.

Why does my trim start early?

With -c copy ffmpeg cuts at the nearest keyframe. Re-encode instead of copying for a frame-accurate cut.

Is anything uploaded?

No, the command is assembled locally in your browser — no files leave your device.

FFmpeg Command Generator

Build ffmpeg commands for video and audio with explained flags.

Support

Works Offline

Privacy First

No Login

No API

Build a command

Pick a task and tune the flags

Task

Input file

Output file

Video codec

Audio codec

CRF quality — 23 (lower = better)

Encoder preset

Audio bitrate

Frame rate (optional, e.g. 30)

Overwrite output (-y)

Quiet logs

MP4 faststart

Command

Copy and paste into your terminal

Shellffmpeg -y -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k -movflags +faststart output.mp4

What each flag does

-yOverwrites the output file without asking.
-crf 23Quality target: lower is better quality and a bigger file (18 ≈ visually lossless, 28 ≈ small).
-preset mediumEncoding speed vs. compression — slower presets give smaller files.
-movflags +faststartMoves the index to the front so the MP4 starts playing before it finishes downloading.

Need something else? The FFmpeg cheatsheet has 46 ready-made commands for video, audio, GIF, HLS and subtitles.

Run it here

Add your video, audio or image and run this exact command in your browser

Drop a file here

Video, audio or image — up to 512 MB, processed locally with ffmpeg.wasm

Input files this command needs

input.mp4→ add a file above

The first run downloads the ffmpeg WebAssembly core (~32 MB) and then caches it. Encoding in the browser is slower than a native install, so keep clips short for heavy re-encodes.

About the FFmpeg Command Generator

Pick a task — compress, convert, resize, trim, extract audio, GIF or thumbnail — set codec, CRF, preset, bitrate and frame rate, and get a ready-to-paste ffmpeg command with a plain-English explanation of every flag.

Popular uses

ffmpeg command generator
ffmpeg builder
ffmpeg compress video
ffmpeg convert mp4
ffmpeg gui online
ffmpeg flags explained

Examples

Compress an MP4

H.264, CRF 23, medium preset

Output

Shellffmpeg -y -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4

Video to GIF

15 fps, 480px wide

Output

Two-pass palettegen / paletteuse command

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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FFmpeg Cheatsheet

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FFmpeg Online — Run Commands in Your Browser

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Run real ffmpeg commands on your video, audio or image — no install.

.editorconfig Generator

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Create an .editorconfig file with per-language overrides.

Frequently asked questions

Compress, trim and convert video in the browser with FFmpeg WASM
How ffmpeg.wasm makes real video editing possible client-side, which presets to use for smaller files, and where the limits are.

Version 1.0.0 · Updated 2026-08-14 · Runs entirely in your browser

FFmpeg Command Generator

About the FFmpeg Command Generator

Popular uses

Examples

Keyboard shortcuts

Related tools

M3U8 / HLS Downloader

Online Video Player (M3U8 / HLS)

Video Format Converter

FFmpeg Cheatsheet

FFmpeg Online — Run Commands in Your Browser

.editorconfig Generator

Frequently asked questions

Does this run ffmpeg for me?

What CRF value should I use?

Which preset is best?

Why does my trim start early?

Is anything uploaded?

Read more