Astc-encoder-py

**Status:** November 2024

The 5.1.0 release is an optimization release, giving moderate performance improvements on all platforms. There are no image quality differences.

* **General:**
* **Feature:** Added a new CMake build option to control use of native gathers, as they can be slower than scalar loads on some common x86 microarchitectures. Build with `-DASTCENC_X86_GATHERS=OFF` to disable use of native gathers in AVX2 builds.
* **Optimization:** Added new `gather()` abstraction for gathers using byte indices, allowing implementations without gather hardware to skip the byte-to-int index conversion.
* **Optimization:** Optimized `compute_lowest_and_highest_weight()` to pre-compute min/max outside of the main loop.
* **Optimization:** Added improved intrinsics sequence for SSE and AVX2 integer `hmin()` and `hmax()`.
* **Optimization:** Added improved intrinsics sequence for `vint4(uint8_t*)` on systems implementing Arm SVE.

Binary release sha256 checksums


a9f61f954f8c6f75675b9b8187454a3b1328c172cb62747715a30937bb8fe7bb astcenc-5.1.0-linux-x64.zip
4ecb330104e05a35febfc0d83b0c128ee2f51b671577e9952ca4278b5455197b astcenc-5.1.0-macos-universal.zip
ff01a6f988aaf5d7f1a139d2cff4c1988f70252b6f53fa3ba72888cc732ba154 astcenc-5.1.0-windows-arm64.zip
c3e5954b9f263e4e13d92892a9e9ef4728abf4acffbf013bb466dd97cc2a0a15 astcenc-5.1.0-windows-x64.zip

**Status:** November 2024

The 5.0.0 release is the first stable release in the 5.x series. The main new feature over the 4.x series is support for the Arm Scalable Vector Extensions (SVE) SIMD instruction set, with both 128-bit and 256-bit backends provided. This gives up to 60% performance improvement on Neoverse V2 with its 256-bit SVE implementation.

* **General:**
* **Bug fix:** Fixed incorrect return type in "None" vector library reference implementation.
* **Bug fix:** Fixed sincos table index under/overflow.
* **Feature:** Changed `ASTCENC_ISA_NATIVE` builds to use `-march=native` and `-mcpu=native`.
* **Feature:** Added backend for Arm SVE fixed-width 256-bit builds. These can only run on hardware implementing 256-bit SVE.
* **Feature:** Added backend for Arm SVE 128-bit builds. These are portable builds and can run on hardware implementing any SVE vector length, but the explicit SVE use is augmented NEON and will only use the bottom 128-bits of each SVE vector.
* **Feature:** Optimized NEON mask `any()` and `all()` functions.
* **Feature:** Migrated build and test to GitHub Actions pipelines.

Binary release sha256 checksums


70183c4346f9fc0f55cd8e3ca5b326cbb4675233b026c02df60657e344c44cc0 astcenc-5.0.0-linux-x64.zip
b8e450250932f07765d868318709964da2a36d41be0538f5c018d8fc72a41e70 astcenc-5.0.0-macos-universal.zip
dbaf1a1329f6fd909457b43e7872092e979ba8ebd9bdf9dbbd950069fa533124 astcenc-5.0.0-windows-arm64.zip
6c22b89f3d437d457c45036c8297ce9cec400f8bdfa019eed71e3b8d343f5ebb astcenc-5.0.0-windows-x64.zip

**Status:** May 2024

The 4.8.0 release is a minor maintenance release.

Reminder - the codec library API is not designed to be binary compatible across versions. We always recommend rebuilding your client-side code using the updated `astcenc.h` header.

* **General:**
* **Bug fix:** Native builds on macOS will now correctly build for arm64 when run outside of Rosetta on an Apple silicon device.
* **Bug fix:** Multiple small improvements to remove use of undefined language behavior, to improve support for deployment using Emscripten.
* **Feature:** Builds using Clang can now build with undefined behavior sanitizer by setting `-DASTCENC_UBSAN=ON` on the CMake configure line.
* **Feature:** Updated to Wuffs library 0.3.4, which ignores tRNS alpha chunks for type 4 (LA) and 6 (RGBA) PNGs, to improve compatibility with libpng.

Binary release sha256 checksums


dfd7fb8056aeb1c9fa19d8c101f9a6a710ffa2000e62d5a536d4a7ca06c81c8d astcenc-4.8.0-linux-x64.zip
26b82cac7a41c99c4a5789df5025d1bc42a02067be4670a5f4639e176083cee2 astcenc-4.8.0-macos-universal.zip
cdf073b42c86e766959e0c363b84b16ca4908b0d1a6304eafa6ae8d32b2dd393 astcenc-4.8.0-windows-arm64.zip
a821d4c58fa5bb5ecf421aabbdb514f0083baea0c0bc0e6d10fba65fe3ceb7b2 astcenc-4.8.0-windows-x64.zip

**Status:** January 2024

The 4.7.0 release is a major maintenance release, fixing rounding behavior in the decompressor to match the Khronos specification. This fix includes the addition of explicit support for optimizing for decode_unorm8 rounding.

Reminder - the codec library API is not designed to be binary compatible across versions. We always recommend rebuilding your client-side code using the updated `astcenc.h` header.

* **General:**
* **Bug fix:** sRGB LDR decompression now uses the correct endpoint expansion method to create the 16-bit RGB endpoint colors, and removes the previous correction code from the interpolation function. This bug could result in LSB bit flips relative to the standard specification.
* **Bug fix:** Decompressing to an 8-bit per component output image now matches the decode_unorm8 extension rounding rules. This bug could result in LSB bit flips relative to the standard specification.
* **Bug fix:** Code now avoids using `alignas()` in the reference C implementation, as the default `alignas(16)` is narrower than the native minimum alignment requirement on some CPU architectures.
* **Feature:** Library configuration supports a new flag, `ASTCENC_FLG_USE_DECODE_UNORM8`. This flag indicates that the image will be used with the decode_unorm8 decode mode. When set during compression this allows the compressor to use the correct rounding when determining the best encoding.
* **Feature:** Command line tool supports a new option, `-decode_unorm8`. This option indicates that the image will be used with the `decode_unorm8` decode mode. This option will automatically be set for decompression (`-d*`) and trial (`-t*`) tool operation if the decompressed output image is stored to an 8-bit per component file format. This option must be set manually for compression (`-c*`) tool operation, as the desired decode mode cannot be reliably determined.
* **Feature:** Library configuration supports a new optional progress reporting callback to be specified. This is called during compression to to allow interactive tooling use cases to display incremental progress. The command line tool uses this feature to show compression progress unless `-silent` is used.
* **Feature:** Prebuilt Linux binary releases updated to use Clang 14 (previously Clang 9) which gives a small performance improvement.

Binary release sha256 checksums


4f596546808c58f2b7e0271302d05df40159cdc7c47645cc96f331229d22ab66 astcenc-4.7.0-linux-x64.zip
176b2c0bf2673d15eb1ba11c1e2691ccb041b79e4076fccd6cd0ece3f75aa2bc astcenc-4.7.0-macos-universal.zip
092bc9023195c9ccef811c97f1e0746e0f803a5397e5a18773566615b077914d astcenc-4.7.0-windows-arm64.zip
deb20ea0cb4ef522ca1eecee82358bfc9cdafd8d4101bc22f28502a0165180bd astcenc-4.7.0-windows-x64.zip

**Status:** November 2023

The 4.6.1 release is a minor maintenance release to fix a performance scaling issue on large core count Windows systems. No other performance or image changes are expected for this release.

* **General:**
* **Optimization:** Windows builds of the `astcenc` command line tool can now use more than 64 cores on large core count systems. This change doubles command line performance for `-exhastive` compression when testing on an 96 core/192 thread system.
* **Feature:** Windows Arm64 native builds of the `astcenc` command line tool are now included in the prebuilt release binaries.

Binary release sha256 checksums


e360aeabf3b5aeda6a7cfabddc49af8b204e28befa04ab8e8942c85620ba071a astcenc-4.6.1-linux-x64.zip
40f19df27799f6f2ad6890c147165f8e077ff6547be57b02d7949677d3f1ea9e astcenc-4.6.1-macos-universal.zip
92cd085b6a2f8f748fd384f2dc8e3c977756ffbe13e263729695cd18233b55a8 astcenc-4.6.1-windows-arm64.zip
0c4ba7af8b5ec22e9bd4f4173866985d2d10b5be137753171481b9629054e38e astcenc-4.6.1-windows-x64.zip

**Status:** November 2023

The 4.6.0 release is a minor release with a few code quality improvements, and a small performance boost.

Reminder - the codec library API is not designed to be binary compatible across versions. We always recommend rebuilding your client-side code using the updated `astcenc.h` header.

* **General:**
* **Bug-fix:** Fixed context allocation for contexts allocated with the `ASTCENC_FLG_DECOMPRESS_ONLY` flag.
* **Bug-fix:** Reduced use of `reinterpret_cast` in the core codec to avoid strict aliasing violations.
* **Optimization:** `-medium` search quality no longer tests 4 partition encodings for block sizes between 25 and 83 texels (inclusive). This improves performance for a tiny drop in image quality.
* **Optimization:** `-thorough` and higher search qualities no longer test the mode0 first search for block sizes between 25 and 83 texels (inclusive). This improves performance for a tiny drop in image quality.
* **Optimization:** `TUNE_MAX_PARTITIONING_CANDIDATES` reduced from 32 to 8 to reduce the size of stack allocated data structures. This causes a tiny drop in image quality for the `-verythorough` and `-exhaustive` presets.

Binary release sha256 checksums


321229025183e9f8f1cdb766b1a036da33a192d56e46bdf8b44295759c36fc9e astcenc-4.6.0-linux-x64.zip
19adae19a7a46b05739fe9285dbac6c960e08504780890bbef4f8eca6663e0d7 astcenc-4.6.0-macos-universal.zip
a140454aa6c2dee29e85a1dc162430a6914123aea62546bfad9885ca336bff24 astcenc-4.6.0-windows-x64.zip