Hi,
In the latest paint.net version (4.2.10), when saving a dds file, the formats at the end of the dropdown list are actually saved as different formats.
A1R5G5B5 gets saved as A4R4G4B4: channel masks = { r=0x00000F00, g=0x000000F0, b=0x0000000F, a=0x0000F000 }
A4R4G4B4 gets saved as R5G6B5: channel masks = {r=0x0000F800, g=0x000007E0, b=0x0000001F, a=0x00000000 }
R5G6B5 gets saved as A8R8G8B8
The various ?8R8G8B8 combinations before A4R5G5B5 seem to be properly saved, R8G8B8 is also correct, and I didn't check the BC formats.
There seems to be no way to actually save A1R5G5B5.
Thanks.