basis_universal

basis_universal v2.1

An LDR/HDR portable GPU supercompressed texture transcoding system.

Build status

Intro

Basis Universal™ v2.1 is an open source supercompressed LDR/HDR GPU compressed texture interchange system from Binomial LLC that supports two intermediate file formats: the .KTX2 open standard from the Khronos Group, and our own “.basis” file format. These file formats support rapid transcoding to virtually any compressed GPU texture format released over the past quarter century.

GPU Textures are Infrastructure

Our overall goal is to simplify the encoding and efficient distribution of portable LDR and HDR GPU texture, image, and short texture video content in a way that is compatible with any GPU or rendering/graphics API.

The system supports seven modes (or codecs). In the order they were implemented:

  1. ETC1S: A supercompressed subset of ETC1 designed for very fast transcoding to other LDR texture formats, low/medium quality but high compression, slightly faster transcoding to other LDR texture formats vs. libjpeg.
  2. UASTC LDR 4x4 (with or without RDO): Custom ASTC 4x4-like format designed for very fast transcoding to other LDR texture formats, high quality
  3. UASTC HDR 4x4: Standard ASTC HDR 4x4 texture data, but constrained for very fast transcoding to BC6H
  4. ASTC HDR 6x6 (with or without RDO): Standard ASTC HDR 6x6
  5. UASTC HDR 6x6 Intermediate (“GPU Photo HDR”): Supercompressed ASTC HDR 6x6
  6. ASTC LDR 4x4-12x12 (all 14 standard ASTC block sizes, with or without basic windowed RDO): Standard ASTC LDR 4x4-12x12
  7. XUASTC LDR 4x4-12x12 (all 14 standard ASTC block sizes, “GPU Photo LDR/SDR”): Latent-space supercompressed ASTC LDR with Weight Grid DCT (Discrete Cosine Transform) for very high quality, extreme bitrate scalability, optional adaptive deblocking (CPU or using a simple GPU pixel shader compatible with mipmapping and filtering), three entropy coding profiles (Zstd, arithmetic or hybrid). See JPEG for ASTC, and the ASTC and XUASTC LDR Usage Guide.

The C/C++ encoder and transcoder libraries can be compiled to native code or WebAssembly (web or WASI), and all encoder/transcoder features can be accessed from JavaScript via a C++ wrapper library which optionally supports WASM multithreading for fast encoding in the browser. WASM WASI builds, for the command line tool and the encoder/transcoder as a WASI module using a pure C API, are also supported.

Full Python support for encoding/transcoding is now available, supporting native or WASM modules, but is still in the early stages of development.

License/Legal

The reference encoder library, transcoder, and most specification documents in this repo (unless otherwise explictly indicated) are Copyright © 2016–2026 Binomial LLC. All rights reserved except as granted under the Apache 2.0 LICENSE. Basis Universal™ is a trademark of Binomial LLC. KTX™ is a trademark of The Khronos Group Inc. See our Apache 2.0 NOTICE file. If you modify the Basis Universal reference source code, specifications, or wiki documents and redistribute the files, you must cause any modified files to carry prominent notices stating that you changed the files (see Apache 2.0 §4(b)).

See our DEP5 file for the complete list of software and their licenses in this repo. The encoder library is Apache 2.0, but it utilizes some open source 3rd party modules (in ‘encoder/3rdparty’ and in the ‘Zstd’ directory) to load .QOI, .DDS, .EXR images, to handle Zstd compression, and to unpack ASTC texture blocks. See the LICENSES folder. The transcoder utilizes no 3rd party libraries or dependencies, other than Zstd (which is optional but limits the transcoder to non-Zstd utilizing codecs).

Supported LDR GPU Texture Formats

ETC1S, UASTC LDR 4x4, XUASTC LDR 4x4-12x12 and ASTC LDR 4x4-12x12 files can be transcoded to:

Supported HDR GPU Texture Formats

UASTC HDR 4x4, ASTC HDR 6x6, and UASTC HDR 6x6 files can be transcoded to:

Supported Texture Compression/Supercompression Modes

  1. ETC1S: A roughly .3-3bpp low to medium quality supercompressed mode based on a subset of ETC1 called “ETC1S”. This mode supports variable quality vs. file size levels (like JPEG), alpha channels, built-in compression, and texture arrays optionally compressed as a video sequence using skip blocks (Conditional Replenishment). This mode can be rapidly transcoded to all of the supported LDR texture formats.

  2. UASTC LDR 4x4: An 8 bits/pixel LDR high quality mode. UASTC LDR is a 19 mode subset of the standard ASTC LDR 4x4 (8bpp) texture format, but with a custom block format containing transcoding hints. Transcoding UASTC LDR to ASTC LDR and BC7 is particularly fast and simple, because UASTC LDR is a common subset of both BC7 and ASTC. The transcoders for the other texture formats are accelerated by several format-specific hint bits present in each UASTC LDR block.

This mode supports an optional Rate-Distortion Optimized (RDO) post-process stage that conditions the encoded UASTC LDR texture data in the .KTX2/.basis file so it can be more effectively LZ compressed. More details here.

Here is the UASTC LDR 4x4 specification document.

  1. UASTC HDR 4x4: An 8 bits/pixel HDR high quality mode. This is a 24 mode subset of the standard ASTC HDR 4x4 (8bpp) texture format. It’s designed to be high quality, supporting the 27 partition patterns in common between BC6H and ASTC, and fast to transcode with very little loss (typically a fraction of a dB PSNR) to the BC6H HDR texture format. Notably, UASTC HDR 4x4 data is 100% standard ASTC texture data, so no transcoding at all is required on devices or APIs that support ASTC HDR. This mode can also be transcoded to various 32-64bpp uncompressed HDR texture/image formats.

Here is the UASTC HDR 4x4 specification document, and here are some compressed example images.

  1. ASTC HDR 6x6 or RDO ASTC HDR 6x6: A 3.56 bits/pixel (or less with RDO+Zstd) HDR high quality mode. Just like mode #3, ASTC HDR 6x6 data is 100% standard ASTC texture data. Here’s a page with details. The current encoder supports weight grid upsampling, 1-3 subsets, single or dual planes, CEM’s 7 and 11, and all unique ASTC partition patterns.

The ASTC HDR decoder, used in the transcoder module, supports the entire ASTC HDR format.

  1. UASTC HDR 6x6 Intermediate (“GPU Photo HDR”): A custom compressed intermediate format that can be rapidly transcoded to ASTC HDR 6x6, BC6H, and various uncompressed HDR formats. The custom compressed file format is described here. The format supports 75 unique ASTC configurations, weight grid upsampling, 1-3 subsets, single or dual planes, CEM’s 7 and 11, and all unique ASTC partition patterns. One of the first HDR GPU texture codecs supporting the delta E ITP (ICtCp) colorspace metric and perceptual saliency maps.

  2. Standard ASTC LDR-4x4-12x12. Supports all standard 14 ASTC block sizes. Transcodable from any ASTC block size to any other supported LDR texture format with adaptive deblocking, including BC7 using the bc7f “one-shot” analytical BC7 encoder (supporting all BC7 modes/features) and ETC1 (using etc1f, which also supports the entire ETC1 format).

The ASTC LDR decoder, used in the transcoder module, supports the entire standard ASTC LDR format (i.e. not just ASTC texture blocks generated using our encoder). The ASTC LDR transcoder can transcode any block size ASTC (4x4 - 12x12) to the other LDR texture formats.

  1. XUASTC LDR 4x4-12x12 (“GPU Photo LDR/SDR”): Supercompressed ASTC with Weight Grid DCT, supporting all 14 standard ASTC block sizes, with adaptive deblocking when transcoding to other texture/pixel formats. Bitrates range from approximately 0.3–5.7 bpp, depending on content, profile, block size, windowed RDO, and Weight Grid DCT quality settings. Typical XUASTC LDR 4×4 (8 bpp in memory) transmission/on-disk bitrate with Weight Grid DCT (where it is least effective) is 1.15–3.5 bpp (typical ≈2.25 bpp), with larger block sizes achieving even lower usable bitrates, down to approximately 0.3 bpp. Like ASTC LDR, the XUASTC LDR transcoder can transcode any block size ASTC (4x4 - 12x12) to the other LDR texture formats, but with additional block-size specific optimizations.

Supports three profiles: context-based range/arithmetic coding (for higher compression ratios), Zstd (for faster and simpler transcoding), or a hybrid profile using both approaches. Transcodable to all other supported LDR texture formats, including fully featured (all 8 modes, all dual-plane channel configurations, all mode settings) BC7. Certain common block sizes (4×4, 6×6, and 8×6) have specializations for particularly fast transcoding directly to BC7, bypassing analytical BC7 encoding (using bc7f) entirely for the most common ASTC configurations (solid color and single-subset CEMs).

Weight Grid DCT can be disabled; however, supercompression remains available with optional, configurable windowed RDO. Compatible with all major image and texture content types, including photographic images, lightmaps, albedo/specular textures, various types of normal maps, luminance-only maps, and geospatial mapping signals.

Supports adaptive deblocking when transcoding from larger block sizes; this can be disabled using a transcoder flag.

One interesting use of XUASTC LDR which works with any of the 14 block sizes: the efficient distribution of texture content compressed to very low bitrates vs. older systems, resulting in game-changing download time reductions. Using the larger XUASTC block sizes (beyond 6x6) with Weight Grid DCT and adaptive deblocking on either the CPU or GPU using a simple shader, any developer can now distribute texture and image content destined for BC7 at .35-1.5 bpp, and cache the transcoded BC7 data on a modern Gen 4 or 5 (10+ GB/sec.) SSD.

XUASTC LDR supports the following ASTC configurations: L/LA/RGB/RGBA CEMs; base+scale or RGB/RGBA direct; base+offset CEMs; Blue Contraction encoding; 1–3 subsets; all partition patterns; and single- or dual-plane modes. Here is the XUASTC LDR specification. Also see the ASTC and XUASTC LDR Usage Guide.

Notes:

Other Features

Both .basis and .KTX2 files support mipmap levels, texture arrays, cubemaps, cubemap arrays, and texture video, in all modes. Additionally, .basis files support non-uniform texture arrays, where each image in the file can have a different resolution or number of mipmap levels.

In ETC1S mode, the compressor is able to exploit color and pattern correlations across all the images in the entire file using global endpoint/selector codebooks, so multiple images with mipmaps can be stored efficiently in a single file. The ETC1S mode also supports skip blocks (Conditional Replenishment) for short video sequences, to prevent sending blocks which haven’t changed relative to the previous frame.

The LDR image formats supported for reading are .PNG, .DDS with mipmaps, .TGA, .QOI, and .JPG. The HDR image formats supported for reading are .EXR, .HDR, and .DDS with mipmaps. The library can write .basis, .KTX2, .DDS, .KTX (v1), .ASTC, .OUT, .EXR, and .PNG files.

The system now supports loading basic 2D .DDS files with optional mipmaps, but the .DDS file must be in one of the supported uncompressed formats: 24bpp RGB, 32bpp RGBA/BGRA, half-float RGBA, or float RGBA. Using .DDS files allows the user to control exactly how the mipmaps are generated before compression.

Building (Native)

The encoding library and command line tool have no required 3rd party dependencies that are not already in the repo itself. The transcoder is a single .cpp source file (in transcoder/basisu_transcoder.cpp) which has no 3rd party dependencies.

We build and test under:

Under Windows with Visual Studio you can use the included basisu.sln file. Alternatively, you can use cmake to create new VS solution/project files.

To build, first install cmake, then:

mkdir build
cd build
cmake ..
make

To build with SSE 4.1 support on x86/x64 systems (ETC1S encoding is roughly 15-30% faster), add -DBASISU_SSE=TRUE to the cmake command line. Add -DBASISU_OPENCL=TRUE to build with (optional) OpenCL support. Use -DCMAKE_BUILD_TYPE=Debug to build in debug. To build 32-bit executables, add -DBASISU_BUILD_X64=FALSE.

After building, the native command line tool used to create, validate, and transcode/unpack .KTX2/.basis files is bin/basisu.

Note we use C++17 for compiling the software. Anything later is too new for us. Compiling the software with a newer C++ version is not supported by us yet.

Running the Precompiled WASM WASI Executables

For smaller images/textures (~4 megatexels or less), there are precompiled, secure, cross-platform 32-bit .WASM WASI executables checked into the bin directory: basisu_mt.wasm (multithreaded) and basisu_st.wasm (single threaded). Quick testing - ETC1S/UASTC LDR 4x4 (all platforms) - multithreaded and single threaded, using wasmtime:

Tested with wasmtime v39.0.0:

cd bin
wasmtime run --dir=. --dir=../test_files --wasm threads=yes --wasi threads=yes ./basisu_mt.wasm -test
wasmtime run --dir=. --dir=../test_files ./basisu_st.wasm -test

For newer versions of wasmtime such as v42.0.1 add --wasm shared-memory=yes:

wasmtime run --dir=. --dir=../test_files --wasm threads=yes --wasm shared-memory=yes --wasi threads=yes ./basisu_mt.wasm -test

See the runwt.sh, runwt.bat, runw.sh, or runw.bat scripts for examples on how to run the WASM executables using wasmtime. Windows example for XUASTC LDR 6x6 compression using the arithmetic profile, with Weight Grid DCT level 70:

cd bin
runwt.bat ../test_files/tough.png -xuastc_ldr_6x6 -quality 70 -xuastc_arith
runwt.bat tough.ktx2

Linux/macOS:

cd bin
chmod +x runwt.sh
./runwt.sh ../test_files/tough.png -xuastc_ldr_6x6 -quality 70 -xuastc_arith
./runwt.sh tough.ktx2

Unfortunately, 32-bit WASM WASI executables have tradeoffs vs. native executables: Limited memory, and slower performance (somewhat mitigatable using WASM threading, which we support). 32-bit WASM WASI memory constraints limit the maximum image/texture size that can be compressed to ASTC LDR or XUASTC LDR to around 4 megapixels. (The other codecs have lower memory requirements.) For Web, we support both WASM and WASM64 (with or without threading), which greatly improves the WASM memory situation. As far as we know as of 2/2026, wasmtime supports WASM64, but the WASI SDK still doesn’t officially support the wasm64-wasi target, but once it does we’ll support it.

Building (WASM WASI)

To build the WASM WASI executables, you will need the WASM WASI SDK installed. The WASI_SDK_PATH environment variable must be set to the correct path where the SDK is installed.

Multithreaded:

mkdir build_wasm_mt
cd build_wasm_mt
cmake -DCMAKE_TOOLCHAIN_FILE=$WASI_SDK_PATH/share/cmake/wasi-sdk-pthread.cmake -DCMAKE_BUILD_TYPE=Release -DBASISU_WASM_THREADING=ON ..
make

Single threaded:

mkdir build_wasm_st
cd build_wasm_st
cmake -DCMAKE_TOOLCHAIN_FILE=$WASI_SDK_PATH/share/cmake/wasi-sdk.cmake -DCMAKE_BUILD_TYPE=Release -DBASISU_WASM_THREADING=OFF ..
make

The WASM WASI executables will be placed in the bin directory. These platform-independent executables are fully functional, and can be executed using a WASM WASI runtime such as wasmtime.

Testing the Codec

The command line tool includes some automated LDR/HDR encoding/transcoding tests:

cd ../bin
basisu -test
basisu -test_hdr_4x4
basisu -test_hdr_6x6
basisu -test_hdr_6x6i
basisu -test_xuastc_ldr

To test the codec in OpenCL mode (must have OpenCL libs/headers/drivers installed and have compiled OpenCL support in by running cmake with -DBASISU_OPENCL=TRUE):

basisu -test -opencl

Compressing and Unpacking .KTX2/.basis Files

basisu -xuastc_ldr_6x6 -quality 75 -effort 4 x.png

-quality 100 disables Weight Grid DCT, leaving just lossless supercompression of ASTC. An alias for -xuastc_ldr_6x6 is -ldr_6x6i (where ‘i’=”intermediate”). All 14 standard ASTC block sizes are supported, from 4x4-12x12: 4x4, 5x4, 5x5, 6x5, 6x6, 8x5, 8x6, 10x5, 10x6, 8x8, 10x8, 10x10, 12x10 and 12x12. The XUASTC LDR to BC7 transcoder has special optimizations for several common block sizes: 4x4, 6x6 and 8x6. When transcoding XUASTC LDR at these particular block sizes, most XUASTC blocks are directly transcoded to BC7 (i.e. directly from the XUASTC latent to the BC7 latent), skipping the real-time analytical bc7f encoding step.

More XUASTC LDR specific options (many of these also apply to standard ASTC - see our ASTC/XUASTC Usage Guide):

basisu -astc_ldr_6x6 -effort 4 x.png

An alias for -astc_ldr_6x6 is -ldr_6x6.

Just like XUASTC LDR, all 14 standard ASTC block sizes are supported, from 4x4-12x12. Internally the XUASTC LDR encoder is used, but standard ASTC block data is output, instead of supercompressed XUASTC LDR. Most XUASTC LDR options also work in ASTC LDR mode.

basisu -quality 100 x.png

basisu -linear x.png

basisu -uastc x.png

basisu x.exr

basisu -hdr_6x6 x.exr  
basisu -hdr_6x6 -lambda 500 x.exr  
basisu -hdr_6x6_level 5 -lambda 500 x.exr

basisu -hdr_6x6i x.exr  
basisu -hdr_6x6i -lambda 500 x.exr  
basisu -hdr_6x6i_level 5 -lambda 500 x.exr

Note the unified -quality and -effort options work in HDR, too. These examples use the older non-unified options, which allow more direct/precise control.

Be aware that the .EXR reader we use is TinyEXR’s, which doesn’t support all possible .EXR compression modes. Tools like ImageMagick can be used to create .EXR files that TinyEXR can read.

Alternatively, LDR images (such as .PNG) can be compressed to an HDR format by specifying -hdr, -hdr_6x6, or -hdr_6x6i. By default LDR images, when compressed to an HDR format, are first upconverted to HDR by converting them from sRGB to linear light and scaled to 100 nits - candela per sq. meter, cd/m². The sRGB conversion step can be disabled by specifying -hdr_ldr_no_srgb_to_linear, and the normalized RGB linear light to nit multiplier can be changed by specifying -hdr_ldr_upconversion_nit_multiplier X.

Note: If you’re compressing LDR/SDR image files to an HDR format, the codec’s default behavior is to convert the 8-bit image data to linear light (by undoing the sRGB transfer function). It then multiplies the linear light RGB values by the LDR->HDR upconversion multiplier, which is in nits. In previous versions of the codec, this multiplier was effectively 1 nit, but it now defaults to 100 nits in all modes. (The typical luminance of LDR monitors is 80-100 nits.) To change this, use the “-hdr_ldr_upconversion_nit_multiplier X” command line option. (This is done because the HDR 6x6 codecs function internally in the ICtCp HDR colorspace. LDR/SDR images must be upconverted to linear light HDR images scaled to a proper max. luminance based on how the image data will be displayed on actual SDR/HDR monitors.)

Some Useful Command Line Options

More Example Command Lines

basisu -uastc -uastc_rdo_l 1.0 -mipmap x.png

-uastc_rdo_l X controls the RDO (Rate-Distortion Optimization) quality setting. The lower this value, the higher the quality, but the larger the compressed file size. Good values to try are between .2-3.0. The default is 1.0.

basisu -mipmap -quality 75 x.png

There are several mipmap options to change the filter kernel, the filter colorspace for the RGB channels (linear vs. sRGB), the smallest mipmap dimension, etc. The tool also supports generating cubemap files, 2D/cubemap texture arrays, etc. To bypass the automatic mipmap generator, you can create LDR or HDR uncompressed .DDS texture files and feed them to the compressor.

basisu -comp_level 2 x.png

On some rare images (ones with blue sky gradients come to mind), you may need to increase the ETC1S -comp_level setting, which ranges from 1 to 6. This controls the amount of overall effort the encoder uses to optimize the ETC1S codebooks and the compressed data stream. Higher -comp_level’s are significantly slower.

basisu x.png -comp_level 2 -max_endpoints 16128 -max_selectors 16128

basisu -tonemap x.exr

basisu -compare a.png b.png

basisu -compare_hdr a.exr b.exr

See the help text for a complete listing of the tool’s command line options. The command line tool is just a thin wrapper on top of the encoder library.

Unpacking .KTX2/.basis files to .PNG/.EXR/.KTX/.DDS files

You can either use the command line tool or call the transcoder directly from JavaScript or C/C++ code to decompress .KTX2/.basis files to GPU texture data or uncompressed image data. To unpack a .KTX2 or .basis file to multiple .png/.exr/.ktx/.dds files:

basisu x.ktx2

Use the -no_ktx and -etc1_only/-format_only options to unpack to less files.

-info and -validate will just display file information and not output any files.

The written mipmapped, cubemap, or texture array .KTX/.DDS files will be in a wide variety of compressed GPU texture formats (PVRTC1 4bpp, ETC1-2, BC1-5, BC7, etc.), and to our knowledge there is unfortunately (as of 2024) still no single .KTX or .DDS viewer tool that correctly and reliably supports every GPU texture format that we support. BC1-5 and BC7 files are viewable using AMD’s Compressonator, ETC1/2 using Mali’s Texture Compression Tool, and PVRTC1 using Imagination Tech’s PVRTexTool. RenderDoc has a useful texture file viewer for many formats. The macOS Finder app supports previewing .EXR, .ASTC and .KTX files in various GPU formats, including ASTC LDR/ HDR. The Windows 11 Explorer can preview .DDS files. The online OpenHDR Viewer is useful for viewing .EXR/.HDR image files.

Pixel Shader Deblocking Sample: CPU + GPU Deblocking Everywhere

The shader_deblocking sample in the repo demonstrates how to use a simple pixel shader to deblock sampled textures of any block size between 4x4-12x12, greatly reducing block artifacts. The sample shader is compatible with mipmapping and bilinear or trilinear filtering. Ultimately, shader deblocking enables the usage of larger ASTC block sizes, reducing bitrate and increasing transcoding speeds. Deblocking is a standard feature of modern image and video codecs, and there’s no reason why it can’t be used while sampling (or transcoding) GPU textures. Using larger ASTC block sizes can significantly reduce GPU memory bandwidth. If bandwidth is the bottleneck — as it often is — the modest ALU and texture sampling cost of deblocking can be effectively free.

XUASTC LDR’s transcoder supports adaptive deblocking when transcoding to other (non-ASTC) formats like BC7, and GPU shader deblocking can be used for ASTC, resulting in a complete deblocking system for ASTC.

Python Support

All key encoder and all transcoder functionality is now available from Python, but this is still in the early stages of development. See the README files in the python directory for how to build the native SO’s/PYD’s. The Python support module supports both native and WASM modules, which is used as a fallback if native libraries can’t be loaded. Python support has been tested under Ubuntu Linux and Windows 11 so far.

Example:

cd python
python3 -m tests.test_backend_loading
========== BACKEND LOADING TEST ==========

Testing native backend...
[Encoder] Using native backend
  [OK] Native backend loaded
Hello from basisu_wasm_api.cpp version 200
  Native get_version() ? 200
  Native alloc() returned ptr = 190977024
  Native free() OK
  [OK] Native basic operations working.

Testing WASM backend...
[WASM Encoder] Loaded: /mnt/c/dev/xuastc4/python/basisu_py/wasm/basisu_module_st.wasm
[Encoder] Using WASM backend
  [OK] WASM backend loaded
Hello from basisu_wasm_api.cpp version 200
  WASM get_version() ? 200
  WASM alloc() returned ptr = 26920160
  WASM free() OK
  [OK] WASM basic operations working.

========== DONE ==========

WebGL Examples

The ‘WebGL’ directory contains several simple WebGL demos that use the transcoder and compressor compiled to WASM with Emscripten. These demos are online here. See more details in the readme file here.

Screenshot of 'texture' example running in a browser. Screenshot of 'gltf' example running in a browser. Screenshot of 'encode_test' example running in a browser.

Building the WASM Modules with Emscripten

Both the transcoder and encoder may be compiled using Emscripten to WebAssembly and used on the web. A set of JavaScript wrappers to the codec, written in C++ with Emscripten extensions, is located in webgl/transcoding/basis_wrappers.cpp. The JavaScript wrapper supports nearly all features and modes, including texture video. See the README.md and CMakeLists.txt files in webgl/transcoder and webgl/encoder.

To build the WASM transcoder, after installing Emscripten:

cd webgl/transcoder/build
emcmake cmake ..
make

To build the WASM encoder:

cd webgl/encoder/build
emcmake cmake ..
make

There are several simple encoding/transcoding web demos, located in webgl/ktx2_encode_test and webgl/texture_test, that show how to use the encoder’s and transcoder’s JavaScript wrapper APIs. They are live on the web here.

Low-level C++ Encoder/Transcoder API Examples

Some simple examples showing how to directly call the C++ encoder and transcoder library APIs are in example/example.cpp.

Installation using the vcpkg dependency manager

You can download and install Basis Universal using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
vcpkg install basisu

The Basis Universal port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository. (9/10/2024: UASTC HDR support is not available here yet.)

Project Policies

See our wiki page: Project Policies: PRs, compiler warnings, release cadence etc..

KTX2 Support Status

Note as of March 2026 we are working with Khronos on the exact details of how we embed XUASTC LDR supercompressed texture data into the KTX2 file format. KTX2 texture files using our previous codecs (including the recently added UASTC HDR 4x4 and UASTC HDR 6x6i formats) can now be interchanged with other KTX2 tools. See our KTX2 technical information document for more info.

Whenever possible, we keep full introspection/transcode compatibility with all of our previously written KTX2 files, even if during standardization a file format change is made. We don’t expect how we embed XUASTC LDR into KTX2 in basisu v2.1 to change.

Repository Licensing with REUSE

The repository has been updated to be compliant with the REUSE license checking tool (https://reuse.software/). See the .reuse subdirectory.

For more useful links, papers, and tools/libraries, see the end of the UASTC HDR 4x4 texture specification.

Security Note

The Basis Universal codecs integrated into this repo fall under Binomial’s responsibility for security reports and fixes. See the GitHub Security tab above, or the file SECURITY.md for reporting information.

E-mail: info @ binomial dot info, or contact us on Twitter

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