: OBS records in MKV by default because it is "crash-safe." If OBS or your computer crashes, the recording up to that point is saved. This blog post on the OBS Studio Wiki explains why MKV is preferred over MP4 for recording.
: If you find your recordings are laggy or the file sizes are too large, this NVIDIA Blog post provides an excellent deep dive into hardware encoding (NVENC) and optimal settings for high-quality video capture. 2022-11-19 22-16-34.mkv
Since this is a common default filename, you are likely looking for help with managing, editing, or fixing these types of video files. Here are some useful resources and blog posts related to handling OBS MKV files: Managing and Optimizing OBS Recordings : OBS records in MKV by default because it is "crash-safe