Video and Audio Converter - MP4, WebM, MP3, GIF, Trim, Compress
Convert MOV, MKV, AVI and WebM to MP4, shrink a video, cut a clip, make a GIF, pull the audio out as MP3 or WAV, remove silence or normalise loudness. FFmpeg runs inside your browser, so the file never leaves your device. Expect minutes for long HD video, seconds for audio.
Real FFmpeg, Running on Your Own Machine
The engine behind this page is FFmpeg compiled to WebAssembly: the same program that most video software uses, running inside the browser in a worker. The first run downloads it once, about 32 MB, and after that it starts instantly. Because nothing is uploaded there is no queue, no size cap set by a server and no copy of your recording on somebody else's disk. The trade-off is speed: the browser cannot use your graphics card's encoder, so converting long high-definition video takes minutes. Audio jobs, trims without re-encoding and GIFs are quick.
MP4 output uses H.264 with AAC audio and the faststart flag, which is what phones, TVs, PowerPoint and every browser expect. A plain trim copies the streams and cuts on the nearest keyframe, which is instant but can be up to a couple of seconds early; tick re-encode for a frame-accurate cut. Silence removal drops pauses quieter than minus 40 dB that last longer than 0.6 seconds, and loudness normalisation brings a recording to the minus 16 LUFS that podcasts and streaming platforms use. For subtitle files themselves, see the Subtitle Converter.
How the Video and Audio Converter Works
- 01Choose a video or audio file. FFmpeg, compiled to WebAssembly, is downloaded once (about 32 MB) and runs in a worker in your browser.
- 02Pick what you want: convert to MP4, WebM, MP3, WAV, M4A or GIF, compress, trim, remove silence or normalise loudness.
- 03Set the options that matter for that job: the size and quality for a conversion, the start and end for a trim, the frame rate and width for a GIF.
- 04Watch the progress and download the result. Nothing leaves your device.
What Runs Where, and What to Expect
This is real FFmpeg, the same program behind most video software, running inside your browser instead of on a server. That is why a phone recording never leaves your device and why there is no upload wait. It is also why speed depends on your machine: a browser cannot use the hardware encoders a native app uses, so converting a ten-minute 1080p video to H.264 takes minutes, not seconds, and files over a few hundred megabytes need a laptop rather than a phone. Remuxing (changing the container without re-encoding, which the tool does for a trim when the formats allow) is instant. Audio jobs are fast at any size.
When to Use This Tool
A .mov from an iPhone that a Windows colleague cannot open. A screen recording that is far too large to email and needs to become a small MP4. A lecture recording where you want only the audio as MP3. A short clip cut from a long video without installing anything. A GIF for a chat or a pull request. A voice memo with long pauses and uneven volume that should be trimmed of silence and normalised before sharing.
Frequently Asked Questions
- No. FFmpeg runs in your browser; the file is read from your disk and the result is written back to it. Closing the tab discards everything.
- The browser version cannot use your graphics card's encoder and runs on one thread. Choose a smaller output size or a faster preset for long videos, or use it for the audio and short-clip jobs it is best at.
- Almost anything FFmpeg reads: MP4, MOV, MKV, AVI, WebM, MPEG, 3GP, FLV, WMV, MP3, WAV, AAC, M4A, OGG, FLAC and more. HEVC video from newer iPhones is decoded in software and is slow.
- Not yet. Subtitle burn-in needs a font shipped with the engine and is on the list. For now, convert subtitles separately with the Subtitle Converter and load them as a separate track in your player.
Is my video uploaded?→
Why is it slower than a desktop app?→
Which formats can it read?→
Can it burn in subtitles?→
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