ChangeLog.md

2.x series change log

This page summarizes the major functional and performance changes in each release of the 2.x series.

All performance data on this page is measured on an Intel Core i5-9600K clocked at 4.2 GHz, running astcenc using 6 threads.

2.2

Status: ⚠️ In development (ETA February 2021)

The 2.2 release is the third release in the 2.x series. It includes ...

Reminder for users of the library interface - the API is not designed to be stable across versions, and this release is not compatible with 2.1. Please recompile your client-side code using the updated astcenc.h header.

• General:
  • Improvement: SSE4.2 profile changed to SSE4.1, which more accurately reflects the feature set used as we were not using any SSE4.2 intrinsics.
• Core API:
  • API Change: Images using region-based metrics no longer need to include padding; all input images should be tightly packed and dim_pad is removed from the astcenc_image structure.
  • API Change: Image data is no longer a 3D array accessed using data[z][y][x] indexing, it's an array of 2D slices. This makes it easier to directly use images loaded from other libraries.

2.1

Status: Released, November 2020

The 2.1 release is the second release in the 2.x series. It includes a number of performance optimizations and new features.

Reminder for users of the library interface - the API is not designed to be stable across versions, and this release is not compatible with 2.0. Please recompile your client-side code using the updated astcenc.h header.

Features:

• Command line:
  • Bug fix: The meaning of the -tH\cH\dH and -th\ch\dh compression modes was inverted. They now match the documentation; use -*H for HDR RGBA, and -*h for HDR RGB with LDR alpha.
  • Feature: A new -fastest quality preset is now available. This is designed for fast "roughing out" of new content, and sacrifices significant image quality compared to -fast. We do not recommend its use for production builds.
  • Feature: A new -candidatelimit compression tuning option is now available. This is a power-user control to determine how many candidates are returned for each block mode encoding trial. This feature is used automatically by the search presets; see -help for details.
  • Improvement: The compression test modes (-tl\ts\th\tH) now emit a MTex/s performance metric, in addition to coding time.
• Core API:
  • Feature: A new quality preset ASTCENC_PRE_FASTEST is available. See -fastest above for details.
  • Feature: A new tuning option tune_candidate_limit is available in the config structure. See -candidatelimit above for details.
  • Feature: Image input/output can now use ASTCENC_TYPE_F32 data types.
• Stability:
  • Feature: The SSE2, SSE4.2, and AVX2 variants now produce identical compressed output when run on the same CPU when compiled with the preprocessor define ASTCENC_ISA_INVARIANCE=1. For Make builds this can be set on the command line by setting ISA_INV=1. ISA invariance is off by default; it reduces performance by 1-3%.

Performance

Key for performance charts:

• Color = block size (see legend).
• Letter = image format (N = normal map, G = greyscale, L = LDR, H = HDR).

Absolute performance vs 2.0 release:

Relative performance vs 2.0 release:

2.0

Status: Released, August 2020

The 2.0 release is first release in the 2.x series. It includes a number of major changes over the earlier 1.7 series, and is not command-line compatible.

Features:

• The core codec can be built as a library, exposed via a new codec API.
• The core codec supports accelerated SIMD paths for SSE2, SSE4.2, and AVX2.
• The command line syntax has a clearer mapping to Khronos feature profiles.

Performance:

Key for performance charts

• Color = block size (see legend).
• Letter = image format (N = normal map, G = greyscale, L = LDR, H = HDR).

Absolute performance vs 1.7 release:

Relative performance vs 1.7 release: