[skocznymroczny]

ktx is Khronos Texture a format for storing compressed textures (=image data) so that they can be uploaded to GPU memory without decompressing step inbetween

drc is Draco Compression, it's a library from Google to compress mesh data

[jsheard]

KTX can just store compressed GPU textures as-is, but in this case they're using the Basis Universal codec which is a bit more involved. Basis stores textures in a super-compressed form, which is decompressed at runtime to produce a less compressed (but still compressed!) format that the GPU can work with. The advantage is that it's smaller over the wire and one source file can decompress to several different GPU formats depending on what the users hardware supports.