If you this file from a suspicious website (like a torrent or "free movie" site) and it is asking you to "download a codec" or "run a guide.exe" to view it, do not do so. This is a common way to spread malware.
: The most reliable free tool for opening almost any video format. VID_20221216_110750_187.mp4.mkv
: Sometimes, simply deleting the .mkv part of the name works if the file was originally an MP4, but this is less likely to work than using a converter. 4. Safety Warning If you this file from a suspicious website
: A free tool where you can drop the file and select the "MP4" preset to convert it. : Sometimes, simply deleting the
If you need the file to be a standard MP4 to use on a phone or TV, you can "remux" it (change the container without losing quality):