basis_universal | Basis Universal GPU Texture Codec | Compression library

basis_universal is a C++ library typically used in Utilities, Compression applications. basis_universal has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. You can download it from GitHub.

Probably the most important concept to understand about Basis Universal before using it: The system supports two very different universal texture modes: The original "ETC1S" mode is low/medium quality, but the resulting file sizes are very small because the system has built-in compression for ETC1S texture format files. This is the command line encoding tool's default mode. ETC1S textures work best on images, photos, map data, or albedo/specular/etc. textures, but don't work as well on normal maps. There's the second "UASTC" mode, which is significantly higher quality (comparable to BC7 and highest quality LDR ASTC 4x4), and is usable on all texture types including complex normal maps. UASTC mode purposely does not have built-in file compression like ETC1S mode does, so the resulting files are quite large (8-bits/texel - same as BC7) compared to ETC1S mode. The UASTC encoder has an optional Rate Distortion Optimization (RDO) encoding mode (implemented as a post-process over the encoded UASTC texture data), which conditions the output texture data in a way that results in better lossless compression when UASTC .basis files are compressed with Deflate/Zstd, etc. In UASTC mode, you must losslessly compress .basis files yourself. .KTX2 files have built-in lossless compression support using Zstandard, which is used by default on UASTC textures. Basis Universal is not an image compression codec, but a GPU texture compression codec. It can be used just like an image compression codec, but that's not the only use case. Here's a good intro to GPU texture compression. If you're looking to primarily use the system as an image compression codec on sRGB photographic content, use the default ETC1S mode, because it has built-in compression. The "-q X" option controls the output quality in ETC1S mode. The default is quality level 128. "-q 255" will increase quality quite a bit. If you want even higher quality, try "-max_selectors 16128 -max_endpoints 16128" instead of -q. -q internally tries to set the codebook sizes (or the # of quantization intervals for endpoints/selectors) for you. You need to experiment with the quality level on your content. For tangent space normal maps, you should separate X into RGB and Y into Alpha, and provide the compressor with 32-bit/pixel input images. Or use the "-separate_rg_to_color_alpha" command line option which does this for you. The internal texture format that Basis Universal uses (ETC1S) doesn't handle tangent space normal maps encoded into RGB well. You need to separate the channels and recover Z in the pixel shader using z=sqrt(1-x^2-y^2).