Video Converter
Change a video’s format or codec on your device — instant when nothing needs re-encoding.
Convert to
What will happen
What can this browser encode?
- Checking…
Copying (repackaging) works for any codec the output format can hold, even ones this browser cannot encode.
About the Video Converter
Convert a video to MP4, WebM, MOV or MKV, and between the H.264, HEVC (H.265), VP9 and AV1 video codecs with AAC, Opus or MP3 audio. You can also lower the resolution or frame rate. Everything runs on your device with the browser’s own media engine (WebCodecs) driven by the open-source Mediabunny library, so the video is never uploaded.
When only the container changes — for example an iPhone .MOV with HEVC and AAC repackaged as .MP4 — the audio and video data are copied without re-encoding: it takes seconds even for long files and there is no quality loss. The page shows, track by track, what will be copied and what will be re-encoded before you start, and which codecs this browser can encode.
How to use it
- Drop a video on the box or click Choose a video. MP4, MOV, M4V, MKV, WebM, MPEG-TS (.ts/.mts/.m2ts), 3GP and Ogg files open; the page lists the codecs inside.
- Pick the output format. Leave Video codec and Audio on “Keep original” for the fastest, lossless result, or choose a codec to re-encode.
- Optionally cap the resolution (it never upscales), lower the frame rate or set the quality used for re-encoded tracks.
- Check What will happen, then press Convert. Re-encoding shows progress, time left and speed; you can cancel at any time.
- Preview the result and press Download. In Chrome or Edge on a computer you can turn on Save straight to a file first, which writes very large outputs to disk as they are made.
Examples
IMG_1234.MOV · HEVC 1920×1080 + AAC · Output MP4, codecs on “Keep original”
IMG_1234.mp4 in a few seconds; both tracks copied, quality and rotation unchanged.
If an older PC or TV cannot play HEVC, choose Video codec: H.264 instead (needs a browser that can decode HEVC).
recording.webm · VP9 + Opus · Output MP4 · Video codec H.264 · Audio AAC
recording.mp4 with H.264 video and AAC audio, which PowerPoint, iPhones and most TVs play.
drone.mp4 · H.264 3840×2160 60 fps · Resolution 1080p · Frame rate 30 fps · Quality Medium
drone-converted.mp4 at 1920×1080 and 30 fps.
promo.mp4 · Output WebM
promo.webm with VP9 video and Opus audio (WebM can only hold VP8/VP9/AV1 and Opus/Vorbis).
Container and codec: what is the difference?
A video file is a container (MP4, MOV, MKV, WebM) holding tracks compressed with a codec (H.264, HEVC, VP9, AV1 for video; AAC, Opus, MP3 for audio). Changing the container alone is a quick, lossless repackage. Changing the codec means decoding and re-encoding every frame, which takes longer and always loses a little quality.
- MP4 (ISO/IEC 14496-12/14): the most compatible choice; holds H.264, HEVC, AV1 and VP9 with AAC, MP3 or Opus.
- MOV: Apple’s QuickTime format; best with H.264/HEVC and AAC, and the usual home of ProRes.
- MKV (Matroska, IETF RFC 9559): holds almost any codec and several audio tracks; less common on TVs and phones.
- WebM: Matroska restricted to VP8, VP9 or AV1 with Opus or Vorbis, for the web.
Which codec should I choose?
- H.264 — plays on practically every phone, PC, TV and editor. Choose it when in doubt.
- HEVC (H.265) — about the same quality as H.264 at a smaller size; Apple devices and recent PCs and TVs play it. Offered only when your device’s encoder supports it.
- AV1 — the most efficient; current browsers and recent Android phones play it, as do many newer computers and TVs, but many older devices cannot.
- VP9 — efficient and royalty-free, mainly used on the web; all current major browsers play it.
For audio, AAC is the safe choice in MP4 and MOV, and Opus is used in WebM.
Browser support
Re-encoding uses WebCodecs, available in Chrome and Edge 94+, Safari 26+ and desktop Firefox 130+. Firefox for Android has no WebCodecs: there the page can still repackage files without re-encoding, and says so. Which codecs can be encoded depends on the browser and the hardware — open What can this browser encode? on the page to see the list for your device. MP3 audio, and AAC on browsers without an AAC encoder, use encoders built into the page.
Limitations
- AVI, WMV/ASF, FLV, MPG/VOB and RealMedia files cannot be opened: browsers have no decoders for the old codecs they contain. The page tells you when a file is one of these.
- Subtitle tracks, chapters and attachments are not copied (use MKV to MP4 to keep text subtitles).
- Re-encoding HDR video produces standard dynamic range (SDR); colours and highlights may look different.
- Portrait phone videos store their turn as rotation metadata, which MP4 and MOV keep but MKV and WebM players ignore, so for MKV or WebM such videos are re-encoded upright (the plan says so before you start).
- Audio with more than two channels is mixed down to stereo when it has to be re-encoded; copied tracks keep their channels.
- Re-encoding speed depends on your device: hardware encoders often run faster than real time, software ones can be slower than real time for 4K.
- Without “Save straight to a file” the converted video is held in memory until you download it, so very large files can fail on phones or low-memory computers.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
Are my videos uploaded?
No. The file is read and converted inside your browser and the result is created on your device. Nothing is sent to MySmartCoPilot or anyone else.
Why was my conversion finished in a second?
Because the codecs inside your file were already allowed in the new format, so the tracks were copied instead of re-encoded. The pictures and sound are bit-for-bit the original; only the packaging changed.
Does converting reduce quality?
Copying never does. Re-encoding always loses a little detail, like saving a JPEG again; High or Very high quality keeps the loss hard to see. Converting to a “better” codec cannot add detail that is not in the original.
Why is HEVC greyed out?
Browsers can only encode HEVC when the device has a hardware HEVC encoder that the browser can use. Choose H.264 (most compatible) or AV1 (smaller files) instead.
Why is the converted file bigger than the original?
Re-encoding at high quality can use a higher bitrate than a heavily compressed original. Pick a lower quality or resolution, or use the Video Compressor, which aims for a size you choose.
Can I convert AVI, WMV or FLV files?
Not in the browser: these usually contain DivX/Xvid, Windows Media or Flash codecs that browsers cannot decode. A free desktop converter such as VLC or HandBrake can turn them into MP4 first.