Portions of this software make use of public domain code originally written by Igor Pavlov (LZMA), RYG (crn_ryg_dxt*), and Sean Barrett (stb_image.c).
If you use this software in a product, an acknowledgment in the product documentation would be highly appreciated but is not required.
crnlib is a lossy texture compression library for developers that ship content using the DXT1/5/N or 3DC compressed color/normal map/cubemap mipmapped texture formats. It was written by the same author as the open source LZHAM compression library.
It can compress mipmapped 2D textures, normal maps, and cubemaps to approx. 1-1.25 bits/texel, and normal maps to 1.75-2 bits/texel. The actual bitrate depends on the complexity of the texture itself, the specified quality factor/target bitrate, and ultimately on the desired quality needed for a particular texture.
crnlib's differs significantly from other approaches because its compressed texture data format was carefully designed to be quickly transcodable directly to DXTn with no intermediate recompression step. The typical (single threaded) transcode to DXTn rate is generally between 100-250 megatexels/sec. The current library supports PC (Win32/x64) and Xbox 360. Fast random access to individual mipmap levels is supported.