: Right-click the file and select Properties to see the "Type of file".

If you need to change the file format for better compatibility (e.g., for mobile devices or specific editing software), use these methods: Method 1: Using VLC Media Player (Simplest)

: Use "Fast 1080p30" or similar for general compatibility. 💡 Quick Comparison MKV (Matroska) MP4 (MPEG-4) Compatibility Moderate (best for PC/VLC) Universal (Phones, TVs, Web) Subtitles Supports multiple soft-subs Limited (often requires "burn-in") Quality Typically lossless or high quality Often more compressed How to Convert MKV to MP4 on Mac OS X - Psychohistory

If your file is named 06. Shor.mkv.mp4 , it might be an MKV file that was manually renamed or an MP4 file with a confusing name.