Astc-encoder-py

**Status:** Released, January 2021

The 2.2 release is the third release in the 2.x series. It includes a number of performance improvements 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 2.1. Please recompile your client-side code using the updated `astcenc.h` header.

* **General:**
* **Feature:** New Arm aarch64 NEON accelerated vector library support.
* **Improvement:** New CMake build system for all platforms.
* **Improvement:** SSE4.2 feature profile changed to SSE4.1, which more accurately reflects the feature set used.
* **Binary releases:**
* **Improvement:** Linux binaries changed to use Clang 9.0.
* **Improvement:** Windows binaries are now code signed.
* **Improvement:** macOS binaries for Apple Silicon platforms now provided.
* **Improvement:** macOS binaries are now code signed and notarized.
* **Command Line:**
* **Feature:** New image preprocess `-pp-normalize` option added.
* **Feature:** New image preprocess `-pp-premultiply` option added.
* **Improvements:** Cleaner error handling for corrupt images.
* **Core API:**
* **API Change:** Images no longer need to include padding. All input images should be tightly packed. The `dim_pad` field 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 N packed 2D slices.
* **API Change:** New `ASTCENC_FLG_SELF_DECOMPRESS_ONLY` flag added to the codec config. Using this flag enables additional optimizations that aggressively exploit implementation- and configuration-specific, behavior. When using this flag the codec can only reliably decompress images that were compressed in the same context session.

Performance

There is one major set of optimizations in this release, related to the new `ASTCENC_FLG_SELF_DECOMPRESS_ONLY` mode. These allow the compressor to only create data tables it knows that it is going to use, based on its current set of heuristics, rather than needing the full set the format allows.

The first benefit of these changes is reduced context creation time. This can be a significant percentage of the command line utility runtime when compressing a small image and/or when using a quick search preset. Compressing the whole Kodak test suite using the command
line utility and the `-fastest` preset is ~30% faster with this release, which is mostly due to faster context creation.

The reduction in the data table size in this mode also improves the core codec speed. Our test sets show an average of 12% improvement in the codec for `-fastest` mode, and an average of 3% for `-medium` mode.

Binary release sha256 checksums


d3e5fe5dd0cad92ae12406654c1f7de563d042b5130c064de852c6293ffdcda2 astcenc-2.2-linux-x64.zip
ff5e095609db0d08560c3fbf0bc6ed19484d77ed0112f822df61305d3345383e astcenc-2.2-macos-aarch64.zip
5662773b923b5ffa0b5c907afd9c5599c977d4736af4bab1f77cbf92a5902a84 astcenc-2.2-macos-x64.zip
733b74264ec3da8fb243cd2720f06b20b030c6d38e330981b8f2fe0531af4345 astcenc-2.2-windows-x64.zip

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

:warning: A reminder for users of the library interface - the library API is not designed to be stable across versions, and this release is not compatible with 2.0. Please recompile the client-side 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

Performance benefits vary based on image color format, ASTC quality settings, and ASTC block size.

* Compressing using `-thorough` is between 1.3x and 1.6x faster than asctenc 2.0.
* Compressing using `-medium` is between 1.4x and 2.1x faster than asctenc 2.0.
* Compressing using `-fast` is between 1.4x and 2.4x faster than asctenc 2.0.
* Compressing using the new `-fastest` setting is 2.1x - 3.8x faster than using astcenc 2.0 `-fast`.

This is first release of the astcenc 2.x series, providing a number of major improvements for content creators.

The core codec performance is now up to three times faster, with optimized builds for the SSE2, SSE4.2, and AVX2 instruction sets.

The core codec now has a clean library API separating the command line wrapper and the main algorithm core. This makes it easier to directly integrate the compressor into other applications.

The command line tool supports a wider range of input and output file formats for both uncompressed files and compressed files.

**Note: this release is not command line compatible with the 1.x series. Some options have been renamed and some options have been removed.**

* Re-enable JPEG and GIF image support

Update all binaries to source version 62fadfc.