This page summarizes the major functional and performance changes in each release of the 5.x series.
All performance data on this page is measured on an Intel Core i5-9600K
clocked at 4.2 GHz, running astcenc
using AVX2 and 6 threads.
Status: February 2025
The 5.2.0 release is a minor maintenance release.
This release includes changes to the public interface in the astcenc.h
header. We always recommend rebuilding your client-side code using the
header from the same release to avoid compatibility issues.
- General:
- Change: Changed sRGB alpha channel endpoint expansion to match the revised Khronos Data Format Specification (v1.4.0), which reverts an unintended specification change. Compared to previous releases, this change can cause LSB bit differences in the alpha channel of compressed images.
- Feature: Arm64 builds for Linux added to the GitHub Actions builds, and Arm64 binaries for NEON, 128-bit SVE 128 and 256-bit SVE added to release builds.
- Feature: Added a new codec API,
astcenc_compress_cancel()
, which can be used to cancel an in-flight compression. This is designed to help make it easier to integrate the codec into an interactive user interface that can respond to user events with low latency. - Bug fix: Removed incorrect
static
variable qualifier, which could result in an incorrecttune_mse_overshoot
heuristic threshold being used if a user ran multiple concurrent compressions with different settings.
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()
andhmax()
. - Optimization: Added improved intrinsics sequence for
vint4(uint8_t*)
on systems implementing Arm SVE.
- 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
Status: November 2024
The 5.0.0 release is the first stable release in the 5.x series. The main new feature is support for the Arm Scalable Vector Extensions (SVE) SIMD instruction set.
- 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()
andall()
functions. - Feature: Migrated build and test to GitHub Actions pipelines.
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