Change container without re-encoding

How it works

1. 1

   Add your video

   Drop in the MOV, MKV, or MP4 you need rewrapped.

2. 2

   Pick the new container

   MP4, MOV, or MKV (WebM for WebM-family sources). The streams are rewrapped, not re-encoded.

3. 3

   Download

   Done in seconds, even for gigabyte files, with zero quality loss.

Rewrapping a file is not the same as converting it

A video file has two layers that people routinely conflate. The container, which is the extension you see, is a wrapper that says where the streams are and how they line up. The codec is what the picture and sound are actually encoded with, and it lives inside. MP4, MOV, and MKV are containers. H.264, HEVC, and AAC are codecs, and any of them can sit inside any of those containers.

That means an MOV from an iPhone and an MP4 usually contain the same thing. The camera wrote H.264 or HEVC video and AAC audio, and the only real difference is the box it was put in. Converting such a file re-encodes the picture from scratch, which takes minutes and throws away quality for no reason. Remuxing lifts the existing streams out and puts them in a new box, which takes seconds and is bit for bit identical, because nothing was decoded in the first place.

The catch is that a container will not accept just any codec. Drop an H.264 stream into MP4 and it fits, which is the common case and the reason MOV to MP4 is nearly instant. Ask for a combination the target container cannot hold and a genuine re-encode is the only way through, and then the converter is the right tool rather than this one.

Change container format with no quality loss and no upload

Because remuxing copies the streams rather than decoding them, the output is not a close approximation of your video, it is your video, in a different wrapper. There is no generation loss, no quality setting to agonize over, and no bitrate decision to make.

It runs on your device, so a large file is not an upload problem, and remuxing is fast enough that the size barely matters: a file that would take twenty minutes to convert is typically rewrapped in seconds, because the expensive part of a conversion is the part that is being skipped.

Most people arrive here because something refused to open a file, and the fix is usually a container swap rather than a conversion. Reach for the converter only when the codec inside genuinely has to change.

Why nothing uploads

Other tools send your video to their servers, which costs them money per file, so they add watermarks, cap file sizes, and make you sign up. This tool does the work right here in your browser using your own device. Your file is never uploaded, so there is no wait, no watermark, no size limit, and no account.

Questions

What's the difference between remuxing and converting?

Converting re-encodes the picture, which takes minutes and always costs some quality. Remuxing just moves the existing streams into a new container, seconds, and bit-for-bit identical quality.

When does remuxing work?

When the streams already fit the target. iPhone MOV files carry H.264 or HEVC, which drop straight into MP4, the classic case. If the streams don't fit, you'll get a clear message pointing at the converter.

Why would I remux MOV to MP4?

MP4 plays on far more devices, players, and websites, and most editors accept it. Remuxing gets you there without touching quality.

Why is it so fast?

No decoding or encoding happens, the video and audio bytes are copied as-is into the new file structure.

Does my video get uploaded?

No. Remuxing happens in your browser; your file never leaves your device.

Read more about this

• Why your video will not upload, and how to fix it

  Upload errors are famously unhelpful: a red toast, a generic message, or a spinner that never finishes. Behind all of them there are only a handful of actual causes, and each one has a specific fix.

• MP4, MOV, MKV, WebM: which one should you use?

  Almost every piece of confusion about video formats comes from one mixed-up idea: people treat the file extension as if it describes the video. It does not. It describes the box the video came in.

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