CAF (Core Audio Format) is a free audio container format developed by Apple and works on macOS 10.4 or later. It can also be opened on macOS 10.3 using QuickTime 7. Apart from audio, CAF can also hold multiple metadata such as file name, album name, composer, and more. It comes with a filename extension of .caf.
Apple QuickTime Player Soundtrack Pro Logic Studio
HEVC MKV is a digital media format that uses HEVC codec, instead of the usual H.264, which is used on typical MKV files. HEVC MKV files are encoded at lower bitrates than H.264 MKV, making them smaller by up to 50%. However, software and hardware support for HEVC MKV files is quite limited as opposed to H.264 MKV, which ranks among the most popular media formats today.
VLC Media Player
MKV File Player