BinomialLLC/basis_universal: Basis Universal GPU Texture Codec

basis_universal v2.0

An LDR/HDR portable GPU supercompressed texture transcoding system.

Intro

Basis Universal v2.0 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 ~25 years.

Our overall goal is to simplify the encoding and efficient distribution of portable LDR and HDR GPU texture, image, and short texture video content …

basis_universal v2.0

An LDR/HDR portable GPU supercompressed texture transcoding system.

Intro

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):

ETC1S: A supercompressed subset of ETC1 designed for very fast transcoding to other LDR texture formats, low/medium quality but high compression
UASTC LDR 4x4 (with or without RDO): Custom ASTC 4x4-like format designed for very fast transcoding to other LDR texture formats, high quality
UASTC HDR 4x4: Standard ASTC HDR 4x4 texture data, but constrained for very fast transcoding to BC6H
ASTC HDR 6x6 (with or without RDO): Standard ASTC HDR 6x6
UASTC HDR 6x6 Intermediate ("GPU Photo"): Supercompressed ASTC HDR 6x6
ASTC LDR 4x4-12x12 (all 14 standard ASTC block sizes): Standard ASTC LDR 4x4-12x12
XUASTC LDR 4x4-12x12 (all 14 standard ASTC block sizes): Supercompressed ASTC LDR 4x4-12x12, very high quality, utilizes Weight Grid DCT (Discrete Cosine Transform) for very high compression ratios

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.

Links

UASTC HDR 4x4/6x6 Specific Links:

Supported LDR GPU Texture Formats

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

ASTC LDR 4x4 L/LA/RGB/RGBA 8bpp
ASTC LDR 4x4-12x12 (XUASTC/ASTC), 0.89-8bpp
BC1-5 RGB/RGBA/X/XY
BC7 RGB/RGBA
ETC1 RGB, ETC2 RGBA, and ETC2 EAC R11/RG11
PVRTC1 4bpp RGB/RGBA and PVRTC2 RGB/RGBA
ATC RGB/RGBA and FXT1 RGB
Uncompressed LDR raster image formats: 8888/565/4444

Supported HDR GPU Texture Formats

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

ASTC HDR 4x4 (8bpp, UASTC HDR 4x4 only)
ASTC HDR 6x6 RGB (3.56bpp, ASTC HDR 6x6 or UASTC HDR 6x6 intermediate only)
BC6H RGB (8bpp, either UASTC HDR 4x4 or UASTC HDR 6x6)
Uncompressed HDR raster image formats: RGB_16F/RGBA_16F (half float/FP16 RGB, 48 or 64bpp), or 32-bit/pixel shared exponent RGB_9E5

Supported Texture Compression/Supercompression Modes

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. 1.

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 are 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.

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.

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.

UASTC HDR 6x6 Intermediate ("GPU Photo"): 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. 1.

Standard ASTC LDR-4x4-12x12. Supports all 14 ASTC block sizes. Transcodable to any other supported LDR texture format.

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

XUASTC LDR 4x4-12x12: Supercompressed ASTC with Weight Grid DCT. Bitrate ranges between approximately .3-5.7bpp, depending on profile, block size, and Weight Grid DCT quality settings. Supports context-based range/arithmetic coding (for higher ratios), Zstd (for faster transcoding), or a hybrid profile using both. Supports all 14 ASTC block sizes. Transcodable to all other supported LDR texture formats. Certain common block sizes (4x4, 6x6, and 8x6) have specializations for particularly fast transcoding directly to BC7.

Supported ASTC configurations: L/LA/RGB/RGBA CEM’s, base+scale or RGB/RGBA direct, base+ofs CEM’s, Blue Contraction encoding, 1-3 subsets, all partition patterns, single or dual plane. Here is the XUASTC LDR specification.

Notes:

Modes #3 (UASTC HDR 4x4) and #4 (RDO ASTC HDR 6x6), and #6 (ASTC LDR 4x4-12x12) output 100% standard or plain ASTC texture data (with or without RDO), like any other ASTC encoder. The .KTX2 files are just plain textures.
The other modes (#1, #2, #5) output compressed data in various custom supercompressed formats, which our transcoder library can convert in real-time to various GPU texture or pixel formats.
Modes #4 (ASTC HDR 6x6) and #5 (UASTC HDR 6x6) internally use the same unified ASTC HDR 6x6 encoder.
Modes #6 (ASTC LDR 4x4-12x12) and #7 (XUASTC LDR 4x4-12x12) internally use the same unified ASTC LDR ASTC encoder.

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:

Windows x86/x64 using Visual Studio 2026, MSVC or clang
Windows ARM using Visual Studio 2022 ARM v17.13.0 or later
macOS (M1) with clang v16.0.0
Ubuntu Linux with gcc v11.4 or clang v14
Arch Linux ARM, on a Pinebook Pro, with gcc v12.1.
Ubuntu Linux 24.04 on RISC-V (Orange PI RV2)

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.

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/basisu directory. These platform-independent executables are fully functional, and can be executed using a WASM WASI runtime such as wasmtime.

Running the WASM WASI Builds

Precompiled single and multithreaded WASM WASI executables have been checked into the bin directory. A WASM WASI runtime, like wasmtime, is required to run them. The WASM executables have been so far tested under Windows, Ubuntu Linux, and macOS. Examples:

Multithreaded (greatly recommended):

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

Single threaded example:

cd bin
wasmtime run --dir=. --dir=../test_files ./basisu_st.wasm -test

Also see the runw.sh and runwt.sh helper scripts.

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

To compress an LDR sRGB PNG/QOI/TGA/JPEG/DDS image to a supercompressed XUASTC LDR 6x6 .KTX2 file, at quality level 75 (valid quality levels 1-100, where higher values=higher quality), effort level 4 (valid effort levels 0-10, higher values=slower compression):

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

An alias for -xuastc_ldr_6x6 is -ldr_6x6i (where ‘i’="intermediate").

The options -xuastc_arith, -xuastc_zstd (the default), and -xuastc_hybrid control the XUASTC LDR profile used. The arithmetic profile trades off transcoding throughput for 5-18% better compression vs. the Zstd profile, and the hybrid profile is a balance between the two.

All 14 standard ASTC block sizes are supported, from 4x4-12x12.

To compress an LDR sRGB image to a standard ASTC LDR 6x6 .KTX2 file, using effort level 4 (valid effort levels 0-10):

basisu -astc_ldr_6x6 -effort 4 x.png

An alias for -astc_ldr_6x6 is -ldr_6x6.

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.

To compress an LDR sRGB image to an ETC1S .KTX2 file, at quality level 100 (the highest):

basisu -quality 100 x.png

For a linear LDR image, in ETC1S mode, at default quality (-quality 50, or the older -q 128):

basisu -linear x.png

To compress to UASTC LDR 4x4, which is much higher quality than ETC1S:

basisu -uastc x.png

To compress an .EXR, Radiance .HDR, or .DDS HDR image to a UASTC HDR 4x4 .KTX2 file:

basisu x.exr

To compress an HDR 6x6 file:

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

To compress an HDR 6x6 file using the compressed intermediate format for smaller files:

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’re using 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 (candelas per square meter). 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 (candela per sq. meter). 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

All codecs now support simple unified "quality" and "effort" settings. `-effort X` [0,10] controls how much of the search space (and how slowly) compression proceeds, and `quality X` [1,100] controls the quality vs. bitrate tradeoff. Internally these settings will be mapped to each codec’s specific configuration settings. Almost all the older settings still work, however. Previously, `-q X`, where X ranged from [1,255], controlled the ETC1S quality setting. This option is still available, but `-quality` is preferred now.

`-debug` causes the encoder to print internal and developer-oriented verbose debug information.

`-stats` to see various quality (PSNR) statistics.

`-linear`: ETC1S defaults to sRGB colorspace metrics, UASTC LDR currently always uses linear metrics, and UASTC HDR defaults to weighted RGB metrics (with 2,3,1 weights). If the input is a normal map, or some other type of non-sRGB (non-photographic) texture content, be sure to use `-linear` to avoid extra unnecessary artifacts. (Angular normal map metrics for UASTC LDR/HDR are definitely doable and on our TODO list.)

Specifying `-opencl` enables OpenCL mode, which currently only accelerates ETC1S encoding.

The compressor is multithreaded by default, which can be disabled using the -no_multithreading command line option. The transcoder is currently single threaded, although it is thread safe (i.e. it supports decompressing multiple texture slices in parallel).

More Example Command Lines

To compress an sRGB PNG/QOI/TGA/JPEG/DDS image to an RDO (Rate-Distortion Optimization) UASTC LDR .KTX2 file with mipmaps:

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.

To add automatically generated mipmaps to an ETC1S .KTX2 file:

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.

To create a slightly higher quality ETC1S .KTX2 file (one with higher quality endpoint/selector codebooks) at the default quality level (128) - note this is much slower to encode:

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.

To manually set the ETC1S codebook sizes (instead of using -quality, or the older -q options), with a higher codebook generation level (this is useful with texture video):

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

To tonemap an HDR .EXR or .HDR image file to multiple LDR .PNG files at different exposures, using the Reinhard tonemap operator:

basisu -tonemap x.exr

To compare two LDR images and print PSNR statistics:

basisu -compare a.png b.png

To compare two HDR .EXR/.HDR images and print FP16 PSNR statistics:

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 supports previewing .EXR and .KTX files in various GPU formats. The Windows 11 Explorer can preview .DDS files. The online OpenHDR Viewer is useful for viewing .EXR/.HDR image files.

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.

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 two 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.

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/examples.cpp.

ETC1S Texture Video Tips

See the wiki here.

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.)

License

The transcoder and core encoder libraries are Apache 2.0. The transcoder utilizes no 3rd party libraries or dependencies. See LICENSE.

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 and .reuse folders.

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.

External Tool Links

Online .EXR HDR Image File Viewer

Windows HDR + WCG Image Viewer - A true HDR image viewer for Windows. Also see the github repo.

RenderDoc

AMD Compressonator

Microsoft’s DirectXTex

PVRTexTool

Mali Texture Compression Tool - Now deprecated

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

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

Here’s the Sponsors wiki page.

basis_universal v2.0

Intro

basis_universal v2.0

Intro

Links

UASTC HDR 4x4/6x6 Specific Links:

Supported LDR GPU Texture Formats

Supported HDR GPU Texture Formats

Supported Texture Compression/Supercompression Modes

Other Features

Building (Native)

Building (WASM WASI)

Running the WASM WASI Builds

Testing the Codec

Compressing and Unpacking .KTX2/.basis Files

Some Useful Command Line Options

-debug causes the encoder to print internal and developer-oriented verbose debug information.

-stats to see various quality (PSNR) statistics.

Specifying -opencl enables OpenCL mode, which currently only accelerates ETC1S encoding.

More Example Command Lines

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

Python Support

WebGL Examples

Building the WASM Modules with Emscripten

Low-level C++ Encoder/Transcoder API Examples

ETC1S Texture Video Tips

Installation using the vcpkg dependency manager

License

Repository Licensing with REUSE

External Tool Links

Similar Posts

`-debug` causes the encoder to print internal and developer-oriented verbose debug information.

`-stats` to see various quality (PSNR) statistics.

Specifying `-opencl` enables OpenCL mode, which currently only accelerates ETC1S encoding.