Seonglae ChoFour Character Code
A 4-byte code (4 ASCII characters) used to identify codec formats of streams within container files
avc1→ H.264/AVC
hvc1→ HEVC/H.265
mp4v→ MPEG-4 Part 2 Video
In FFmpeg, we specify this FOURCC like
-tag:v hvc1 to ensure player compatibility.