Remuxing
Also known as: rewrapping, remux, container conversion
Moving the existing video and audio streams into a different container, for example MKV to MP4, without re-encoding. Fast, lossless and quality-neutral.
Updated
What it means
A video file is compressed streams inside a container. Remuxing takes those streams and repackages them into another container, copying the compressed data bit for bit. Nothing is decoded or re-encoded, so the picture and sound stay identical to the original, and the process takes only seconds even for long files.
The classic use is turning an MKV screen recording into an MP4 that editors and phones accept, or rewrapping a MOV as MP4 for a platform that prefers it. As long as the new container supports the codec inside, remuxing is the cleanest way to change formats.
It is the opposite of transcoding, which rebuilds the video and can lose quality.
How it works in practice
Free tools and many recording apps offer a remux option. You choose the input file and the target container, and the tool copies the streams. Some also let you drop or add audio tracks and subtitles during the process.
Remuxing is also how lossless trimming works: the tool cuts at keyframes and writes the remaining streams to a new file without re-encoding. That is why such trims can only start at certain points.
If remuxing fails, the codec probably is not supported by the target container, and a transcode is needed instead.
What to watch out for
Remuxing does not change the codec, so it will not fix compatibility problems caused by the codec itself. An HEVC stream remuxed into MP4 is still HEVC, and a device that cannot decode HEVC still cannot play it.
Some metadata can be lost, depending on the tool and container: camera telemetry, chapter markers, color tags or rotation flags. Test the output in your editor before deleting the original.
Variable frame rate recordings stay variable after a remux, so editing problems caused by VFR need a different fix, usually a conversion to constant frame rate.
How RawClip handles it
RawClip accepts MP4 and MOV, and MKV and AVI are accepted too. If a clip is in an unusual container, remuxing it to MP4 is a quick, lossless way to prepare it before upload for your highlight.