First version of HEIC operation with 16 bits color depth support. It do not work yet properly :

digikam.dimg: Saving to "CANON-EOS350D-01.heic" with format: "heic"
HEIC number of bits per pixels: 48
HEIC plane details: ptr= 0x7f2788d34010 stride= 62544
Error while processing HEIC image: Encoder plugin generated an error: Unsupported bit depth: Bit depth not supported by x265

I suspect that libx265 only support 12 bits color depth