Remuxing changes the container around existing audio and video streams without re-encoding the streams themselves.
Remuxing can be lossless.
It is usually faster than transcoding.
It only works when the target container supports the streams inside.
Remuxing means taking the existing audio, video, subtitle, or metadata streams out of one container and placing them into another container.
Because the actual media streams are copied instead of re-encoded, remuxing can preserve quality exactly.
A common example is changing an MKV file to an MP4 file while keeping the same H.264 video and AAC audio. If MP4 supports the streams, the process can be fast and lossless.
If the streams are not compatible with the target container or device, transcoding may be needed instead.
| Question | Remuxing | Transcoding |
|---|---|---|
| Does it re-encode? | No | Yes |
| Is it usually fast? | Yes | Slower |
| Can it lose quality? | Usually no | Often yes |
| Can it fix codec incompatibility? | No, not if the codec itself is unsupported | Yes, by creating a supported codec version |
Remux means repackaging existing media streams into a different container without re-encoding them.
Usually no. Remuxing copies the existing streams, so the audio and video quality can stay exactly the same.
It is usually much faster than transcoding because the media streams are copied instead of re-encoded.
Yes, if the streams inside the MKV are compatible with MP4 and are remuxed instead of transcoded.
No. Remuxing can change the container, but it does not change the codec inside the file.