video-toolsVideo Codecs and Containers Explained (H.264, HEVC, VP9, AV1, MP4 vs MKV)
The difference between a codec and a container, in plain English (H.264, HEVC, VP9 and AV1 vs MP4, MKV and WebM) so you always pick the right export.
6 mins read
Video Converter, Change Video Format Online with FFmpeg
Turn any clip into the format you actually need. Convert between MP4, WebM, MOV, AVI, MKV and GIF with real FFmpeg transcoding, a target-format picker, an MP4 quality control and a preview player: all in your browser, never uploaded.
100% browser processingFree · no sign-up
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What is the video converter?
The Video Converter transcodes between MP4, WebM, MOV, AVI, MKV and GIF using FFmpeg in the browser, picking the correct codec pipeline for whichever target you choose. It offers MP4 quality control, web-ready faststart output, plus an in-page preview and download. Free to use, with every file processed privately and nothing uploaded.
The GigAI Video Converter runs a full FFmpeg build compiled to WebAssembly right inside your browser tab, so it can re-container and re-encode a video without ever sending your footage to a server. Formats are the quiet reason a video refuses to cooperate: a phone's.MOV won't drop into a Windows editor, a.MKV won't play in Safari, a site demands WebM, and a design tool only takes MP4 or GIF. Drop your file, choose the target format from the picker, and the tool transcodes with the right codec pipeline for each container (H.264/AAC for MP4, MOV and MKV, VP9/Opus for WebM, and a palette-optimized encode for GIF) with faststart enabled on MP4/MOV so it plays and streams the instant it loads. When you convert to MP4 you also get a genuine quality control mapped to the H.264 CRF, so you can keep it visually clean or trade some detail for a smaller file. The other targets use each format's proven defaults. The result plays right in the page before you download, so you can confirm the picture and audio survived the round-trip. Everything is client-side, so there's no upload wait and no privacy tradeoff, personal recordings, unreleased footage and confidential captures never leave your machine. Be honest with yourself about the engine: WebAssembly FFmpeg is meaningfully slower than a native converter and it's memory-bound, so a short clip converts in seconds while a large one takes real time behind a determinate progress bar. GIF output in particular balloons fast, so it's best kept to short clips. Close the tab and every byte is gone.
- Difficulty:
- Medium
- Typical time:
- ~1–2m
- Processing:
- 100% browser processing
Last updated
How to use the video converter
- 1
Drop your video
Drag an MP4, MOV, WebM, MKV, AVI or other common video onto the workspace, or click to browse. It's read locally and you'll see its size, duration and dimensions right away.
- 2
Pick the target format
Choose MP4, WebM, MOV, AVI, MKV or GIF from the picker. If you're converting to MP4, set the quality dial. The first run loads the FFmpeg engine once, a one-time moment.
- 3
Convert
Press Convert. A determinate progress bar tracks the transcode locally, quick for short clips, longer for large ones since this is WebAssembly, not native code.
- 4
Preview & download
Play the converted result to confirm it looks and sounds right, then download the new file, or reset and try a different format or quality.
What Video Converter includes
Six formats, one picker
Convert to MP4, WebM, MOV, AVI, MKV or GIF from the same clip. Pick the target you need and the converter selects the correct codec pipeline for that container automatically.
Real FFmpeg, in your browser
A full FFmpeg build compiled to WebAssembly does the transcode with libx264/AAC, VP9/Opus and palette-based GIF, the same engine desktop converters use, with no upload, account or install.
MP4 quality control
When you convert to MP4 you get a plain-English quality dial mapped to the H.264 CRF, from near-lossless to compact, so you can balance clarity against file size instead of guessing.
Web-ready output
MP4 and MOV are written with faststart so they play and stream the instant they load, and WebM comes out VP9/Opus for modern browsers. No re-muxing later just to put it online.
Preview before you download
The converted result plays right in the page so you can confirm the picture and audio came through cleanly before you commit: the sanity check a command line never gives you.
100% private, nothing uploaded
Conversion happens on your device with a self-hosted engine. Personal recordings, unreleased footage and confidential captures are never uploaded, stored or logged.
Why use our video converter
Make the file your app will accept
Editors, browsers, upload forms and design tools each demand specific containers. One pass here turns a stubborn .MOV or .MKV into the MP4, WebM or GIF the app will actually take.
No upload wait, no privacy tradeoff
Server converters make you upload the whole file first and trust them with it. Here the video never leaves your browser, so there's no upload bar and nothing to hand over.
Control quality where it counts
MP4 conversion exposes a real H.264 quality dial and a preview player, so you can keep it crisp or shrink it deliberately, and confirm the result before downloading.
Broadly-compatible results
MP4 comes out H.264/AAC with faststart and WebM as VP9/Opus: mainstream, well-supported codecs that play across phones, browsers and editors instead of a niche format you'll fight.
Built for the way you work
From quick one-off fixes to daily workflows, see how people put this tool to use.
- Video editor
Get a phone .MOV into your timeline
An iPhone .MOV or a camera .MKV can choke a Windows or older editor. Convert it to a clean H.264 MP4 first so it imports, scrubs and renders without fighting the codec.
- Web developer
Produce a WebM for the browser
Background loops and inline clips are lighter and more compatible as WebM. Convert an MP4 source to VP9/Opus WebM to serve modern browsers efficiently without a build step.
- Designer / Marketer
Turn a clip into a shareable GIF
Need a soundless loop for a doc, chat or README? Convert a short clip to a palette-optimized GIF that plays everywhere, right in the browser and without a watermark.
- Privacy-conscious user
Re-format sensitive footage locally
Personal, medical or confidential recordings shouldn't be uploaded to a stranger's converter. Change the format entirely in your browser so nothing ever leaves the device.
Supported formats
Accepts MP4, MOV, WebM, MKV and AVI, and produces MP4, WebM, MOV, AVI and MKV, all processed locally in your browser.
Input formats
- MP4
- MOV
- WebM
- MKV
- AVI
- M4V
- GIF
Output formats
- MP4
- WebM
- MOV
- AVI
- MKV
- GIF
Frequently asked questions
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Comparisons & guides
Go deeper on the concepts behind the video converter.
MP4 vs WebM: Which Video Format Should You Use?
ComparisonMP4 is the universally compatible video container. WebM is the open, royalty-free format tuned for the web. Here's exactly when each one wins.
Read the comparisonMOV vs MP4: What's the Difference and Which to Use?
ComparisonMOV is Apple's QuickTime container built for editing. MP4 is the cross-platform standard for sharing. Here's when each format is the right call.
Read the comparisonGIF vs MP4: Which Is Better for Short Looping Video?
ComparisonAnimated GIFs are universal and autoplay silently, but MP4 delivers the same motion at a fraction of the size with vastly better quality. Here's when to use each.
Read the comparisonGuides & articles
- video-tools
Common problems, solved
Hit a snag? Here are quick fixes for the issues people run into most.
The conversion is taking a long time.
That's expected for large or long clips. This is FFmpeg compiled to WebAssembly, which is slower than a native app and memory-bound. Keep the tab focused and watch the progress bar. For very large files, trim or downscale the source first, and remember GIF output is the heaviest.
The tab ran out of memory or the convert failed on a big file.
WASM has a memory ceiling. Close other heavy tabs and try again. If it still fails the file is likely too large for in-browser transcoding, shorten it or use a lower-resolution source. As a loose guide, keep inputs under a few hundred MB.
My GIF came out huge or choppy.
GIF is an old, uncompressed-ish format that balloons with length, size and frame rate. Convert a short clip (a few seconds) rather than a full video. For anything longer, MP4 or WebM will be far smaller and smoother.
The converted file won't open in my player.
Some players are picky about containers. MP4 (H.264/AAC) is the safest, most universal choice, convert to that if a WebM, MKV or MOV won't open, and it should play virtually everywhere.
Get the most out of it
When in doubt, convert to MP4. H.264/AAC with faststart is the most widely-playable output across phones, browsers and editors.
Only GIF and MP4 balloon or shrink dramatically with settings. For MP4, use the quality dial to trade a little detail for a much smaller file.
The FFmpeg engine loads once per session on your first convert. After that, subsequent conversions skip straight to transcoding.
Keep GIF conversions to a few seconds. The format has no real inter-frame compression, so length and resolution blow the size up fast.
Always play the preview before downloading, it's the quickest way to catch audio that dropped or a format your target app still won't accept.
What's new
Recent updates and improvements to the video converter.
Initial release: in-browser transcoding via self-hosted FFmpeg (WebAssembly) with a target-format picker (MP4, WebM, MOV, AVI, MKV, GIF), correct codec pipeline per container, a preview player and one-click download.
Added a real H.264 quality dial for MP4 output mapped to CRF, faststart on MP4/MOV for instant web playback, and a clearer one-time engine-loading state with a determinate progress bar.
Improved GIF guidance and memory handling for large files, refined per-format defaults for cleaner output, and added drag-and-drop plus reset-and-retry to the workspace.
Keep exploring
Problems we solve
Definitions
From the blog
Explore categories
Compare formats
By file type
Common tasks
Your privacy is built in
Your video is read and transcoded entirely in your browser using a self-hosted FFmpeg (WebAssembly) engine. It is never uploaded to any server. Nothing is stored, logged or transmitted, so you can safely convert personal, confidential or unreleased footage. There's no upload step and no cloud copy. Close the tab and every byte is gone.
- Runs in your browser
- No uploads
- Nothing stored
Ready to try the video converter?
Free, private and instant. Video Converter runs right in your browser.