Zudem ist „.m4v“ nur eine andere Dateiendung für MPEG-4-Videos. Man kann die „Ergebnis.m4v“-Datei also getrost in „Ergebnis.mp4“ umbenennen.
Oder gleich im Handbrake-Menü „Datei → Einstellungen“ im Reiter „Allgemein“ die Option „iPod/iTunes-freundliche Dateierweiterung (.m4v) für MP4 verwenden“ deaktivieren.
Aber wie Franz sagte, ist das Matroska-Behälterformat besser.
https://handbrake.fr/docs/en/latest/advanced/containers.html
Formats / containers
Containers are files that wrap around video and audio tracks—indexing and organizing the streams for playback—in addition to providing advanced features, like chapters similar to those on DVDs.
HandBrake supports two widely supported formats. MKV and MP4 (Sometimes seen as M4v)
[..]
MP4 vs M4v
They are the exact same file, the only difference is the extension. MP4 vs M4v.
For MP4 files, HandBrake will automatically use the extension M4V when you pass-through audio (AC3), use SRT subtitles or have chapter markers enabled.
You can simply change the file extension between .mp4 and .m4v as the file is exactly the same. There are no differences in the content or container itself.
You can disable the option to automatically set this in !HandBrakes preferences.
Note: QuickTime or any QT based application will not be able to play a MP4 file with these features enabled, unless it has the extension “.m4v”