(Except there is no profit, only pain) In OBS 30.2 I introduced the new "Hybrid MP4" output format which solves a number of complaints our users have had for pretty much all of OBS's existence; It's resilient against data loss like MKV, but widely compatible like regular MP4. Getting here was quite a journey, and involved fixing several other bugs in OBS that were only apparent once diving this deep into how the audio and video data is stored. In this post I'll try to explain how MP4 works, what the drawbacks were to regular/fragmented MP4, and how I tried to solve them with a hybrid approach. QTFF, BMFF, WTF The MP4 file format we all know and love today is based on Apple's "QuickTime File Format" (QTFF) - mostly just known as "MOV" - which was originally created in the 90s. It was adapted by the International Organization for Standardization (ISO) to create the MP4 File Format in 2001,