ffmpeg -i input.mkv -c:v libx264 -crf 23 -c:a aac output.mp4
Parameters explained:
Create MPV config file:
mkdir -p ~/.config/mpv
nano ~/.config/mpv/mpv.conf
Add these lines:
hwdec=auto-safe
vo=gpu
profile=gpu-hq
Linux Mint prioritizes open-source software. HEVC (H.265) is heavily patent-encumbered. While the operating system includes robust open-source decoders (like libavcodec), they often lack full support for the latest HEVC profiles (like 10-bit or Main12) or optimized hardware decoding. As a result, your CPU struggles to software-decode the video, leading to stuttering, high fan noise, or outright failure to play the file.
The MKV (Matroska) container adds another layer: it supports almost any codec. Your system might read the MKV file structure but then fail when it encounters the HEVC video stream inside.