Astc-encoder-py

**Status:** July 2022

The 4.0.0 release introduces some major performance enhancements, and a number of larger changes to the heuristics used in the codec to find a more effective cost:quality trade off. The core compressor library is between 1.2x (4x4 blocks) and 1.6x (6x6 blocks) faster than the previous 3.7 release. The core decompressor library is 1.25x faster than the 3.7 release.

* **General:**
* **Change:** The `-array` option for specifying the number of image planes for ASTC 3D volumetric block compression been renamed to `-zdim`.
* **Change:** The build root package directory is now `bin` instead of `astcenc`, allowing the CMake install step to write binaries into
`/usr/local/bin` if the user wishes to do so.
* **Feature:** A new `-ssw` option for specifying the shader sampling swizzle has been added as convenience alternative to the `-cw` option. This is needed to correct error weighting during compression if not all components are read in the shader. For example, to extract and compress two components from an RGBA input image, weighting the two components equally when sampling through `texture().ra` in the shader, use `-esw ggga -ssw ra`. In this example `-ssw ra` is equivalent to the alternative `-cw 1 0 0 1` encoding.
* **Feature:** The `-a` alpha weighting option has been re-enabled in the backend, and now again applies alpha scaling to the RGB error metrics when encoding. This is based on the maximum alpha in each block, not the individual texel alpha values used in the earlier implementation.
* **Feature:** The command line tool now has `-repeats <count>` for testing, which will iterate around compression and decompression `count` times. Reported performance metrics also now separate compression and decompression scores.
* **Feature:** The core codec is now warning clean up to `/W4` for both MSVC `cl.exe` and `clangcl.exe` compilers.
* **Feature:** The core codec now supports arm64 for both MSVC `cl.exe` and `clangcl.exe` compilers.
* **Feature:** `NO_INVARIANCE` builds will enable the `-ffp-contract=fast` option for all targets when using Clang or GCC. In addition AVX2 targets will also set the `-mfma` option. This reduces image quality by up to 0.2dB (normally much less), but improves performance by up to 5-20%.
* **Optimization:** Angular endpoint min/max weight selection is restricted to weight `QUANT_11` or lower. Higher quantization levels assume default 0-1 range, which is less accurate but much faster.
* **Optimization:** Maximum weight quantization for later trials is selected based on the weight quantization of the best encoding from the 1 plane 1 partition trial. This significantly reduces the search space for the later trials with more planes or partitions.
* **Optimization:** Small data tables now use in-register SIMD permutes rather than gathers (AVX2) or unrolled scalar lookups (SSE/NEON). This can be a significant optimization for paths that are load unit limited.
* **Optimization:** Decompressed image block writes in the decompressor now use a vectorized approach to writing each row of texels in the block, including to ability to exploit masked stores if the target supports them.
* **Optimization:** Weight scrambling has been moved into the physical layer; the rest of the codec now uses linear order weights.
* **Optimization:** Weight packing has been moved into the physical layer; the rest of the codec now uses unpacked weights in the 0-64 range.
* **Optimization:** Consistently vectorize the creation of unquantized weight grids when they are needed.
* **Optimization:** Remove redundant per-decimation mode copies of endpoint and weight structures, which were really read-only duplicates.
* **Optimization:** Early-out the same endpoint mode color calculation if it cannot be applied.
* **Optimization:** Numerous type size reductions applied to arrays to reduce both context working buffer size usage and stack usage.

Binary release sha256 checksums


7899f73ee2820b0e7d73b38fda6feb58948a30b511dd123ec4b7c89f3aae531a astcenc-4.0.0-linux-x64.zip
9697d0ad63910cd4f1fd8be51203e9c1873aa6d219ac70540ad0f37e19dd3e63 astcenc-4.0.0-macos-aarch64.zip
26866ad79d80a6153f1746516004e5a95df07c55c6866e44ed63bb7953c7532e astcenc-4.0.0-macos-x64.zip
b83a7d0c88d7e720828bf91655ad4acccee95b2d8086835ef26879b905777172 astcenc-4.0.0-windows-x64.zip

The 3.7 release contains another round of performance optimizations, including significant improvements to the command line front-end (faster PNG loader) and the arm64 build of the codec (faster NEON implementation).

Change log

**General:**
* **Feature:** The command line tool PNG loader has been switched to use the Wuffs library, which is significantly faster than the current implementation.
* **Feature:** Support for non-invariant builds returns. Opt-in to slightly faster, but not bit-exact, builds by setting `-DNO_INVARIANCE=ON` for the CMake configuration. This improves performance by around 2%.
* **Optimization:** Changed SIMD `select()` so that it matches the default NEON behavior (bitwise select), rather than the default x86-64 behavior (lane select on MSB). Specialization `select_msb()` added for the one case we want to select on a sign-bit, where NEON needs a different implementation. This provides a significant (>25%) performance uplift on NEON implementations.

Binary release sha256 checksums


f69c2acbb3b07386cc95001c253cddfa567e71b9618682856f0ff600955cc2ba astcenc-3.7-linux-x64.zip
41c691613e15d844bac56e97a042cc8aea7bc7e8e76fc767ffe875a4d8c5e995 astcenc-3.7-macos-aarch64.zip
5608f4c0b3e1d56a30070cdf61aff42050576833ac7e2719031cec461aa4d102 astcenc-3.7-macos-x64.zip
ecb0e1a5dcbfbaca8a38630e427638380b9d337c266660b39738260e1df5244a astcenc-3.7-windows-x64.zip

The 3.6 release contains another round of performance optimizations. There are no interface changes in this release, but in general the API is not designed to be binary compatible across versions. We always recommend rebuilding your client-side code using the updated `astcenc.h` header.

Change log

**General:**
* **Feature:** Compressor configurations no longer require the `SELF_DECOMPRESS_ONLY` flag to use defragmented data tables. Tables are always sorted to store active data table entries at the start of the list, with inactive entries stores at the end. If the `SELF_DECOMPRESS_ONLY` flag is specified the inactive entries are not created, reducing context creation time and memory footprint.
* **Feature:** Image quality for 4x4 `-fastest` compression has been improved.
* **Optimization:** Decimation modes are reliably excluded from processing when they are only partially selected in the compressor configuration (e.g. if used for single plane, but not dual plane modes). This is a significant performance optimization for all quality levels.
* **Optimization:** Fast-path block load function variant added for 2D LDR images with no swizzle. This is a moderate performance optimization for the `-fast` and `-fastest` quality levels.

Binary release sha256 checksums


cd0392bccb64da8177f3e3869c5ac37aea6d096cbbf804ecc0b62b3581a2b56b astcenc-3.6-linux-x64.zip
a04c3e930ba7397fb0c33fa6a70bb64ff798cd42a031124164a164f81634930c astcenc-3.6-macos-aarch64.zip
b51f7f53c7c113f708666dca11dcaec545c535c081bc9b27030cf2eee73a279a astcenc-3.6-macos-x64.zip
2a9c1edf98e1d28d542fb728c88f9afc03c9de18e5662b348e44be3f1a227059 astcenc-3.6-windows-x64.zip

The 3.5 release contains another round of performance optimizations. There are no interface changes in this release, but in general the API is not designed to be binary compatible across versions. We always recommend rebuilding your client-side code using the updated astcenc.h header.

Change log

**General:**
* **Feature:** Compressor configurations using the `SELF_DECOMPRESS_ONLY` flag store compacted partition tables, which significantly improves both context creation time and compressor runtime performance.
* **Feature:** Bilinear infill for decimated weight grids supports a new variant for half-decimated grids which are only decimated in one axis, which gives a small performance boost across all quality levels.

Binary release sha256 checksums


08e4dc8e263c0dcb0dc8d9d63b194ff881b8737de8f554458b2d66935da9c4fe astcenc-3.5-linux-x64.zip
ced2d434cbade742ef1f3879f90918e983381ddec1cea794ea30e6d4b2fa9573 astcenc-3.5-macos-aarch64.zip
806d86f69d84d4c30d0e6f8ca7cfe222005e51ca86684e265dd5aa4b68f9ddcf astcenc-3.5-macos-x64.zip
b531b89a677a41535f2704d50677904ae7ffefe83b403dfbbf6bfe6b028d573d astcenc-3.5-windows-x64.zip

**Status:** Released

The 3.4 release introduces another round of optimizations, removing a number of power-user configuration options to simplify the core compressor data path. It is expected that there is some minor loss of image quality at the same compressor effort setting, but the improved performance allows a higher compressor effort level to be used for the same runtime as earlier releases.

Reminder for users of the library interface - the API is not designed to be binary compatible across versions, and this release is not compatible with earlier releases. Please update and rebuild your client-side code using the updated `astcenc.h` header.

* **General:**
* **Feature:** Many memory allocations have been moved off the stack into dynamically allocated working memory. This significantly reduces the peak stack usage, allowing the compressor to run in systems with 128KB stack limits.
* **Feature:** Builds now support `-DBLOCK_MAX_TEXELS=<count>` to allow a compressor to support a subset of block sizes. This can reduce binary size and runtime memory footprint, and improve performance.
* **Feature:** The `-v` and `-va` options to set a per-texel error weight function are no longer supported.
* **Feature:** The `-b` option to set a per-texel error weight boost for block border texels is no longer supported.
* **Feature:** The `-a` option to set a per-texel error weight based on texel alpha value is no longer supported as an error weighting tool, but is still supported for providing sprite-sheet RDO.
* **Feature:** The `-mask` option to set an error metric for mask map textures is still supported, but is currently a no-op in the compressor.
* **Feature:** The `-perceptual` option to set a perceptual error metric is still supported, but is currently a no-op in the compressor for mask map and normal map textures.
* **Bug-fix:** Corrected decompression of error blocks in some cases, so now returning the expected error color (magenta for LDR, NaN for HDR). Note that `astcenc` determines the error color to use based on the output image data type not the decoder profile.

Binary release sha256 checksums

**Note:** Due to a delay publishing the binaries, caused by a DevOps pipeline upgrade, these binaries have actually been built from a slightly newer git hash (`c82259f`) than the 3.4 tag. This includes a number of performance optimizations which didn't land in time for the 3.4 release tag, as well as a change to use ClangCL to compile the Windows builds.


ceb268d8eb393281bf5646450c17f64c7fbfeddad7f02c52c28ab1b74f129fce astcenc-3.4-linux-x64.zip
0619c92b1ba3c24f209c7affb21b56d29aeaef6bdbb1a73793cad560853e53c9 astcenc-3.4-macos-aarch64.zip
faf389fa734855fdf5c070920ad682c083d354d0b8e5310a6d4134cea1921485 astcenc-3.4-macos-x64.zip
d85c89f6a6251ccda71b3aace66502a7b54668b8bc23632180bfc48cebeb74de astcenc-3.4-windows-x64.zip

**Status:** Released

The 3.3 release improves image quality for normal maps, and two component textures. Normal maps are expected to compress 25% slower than the 3.2 release, although it should be noted that they are still faster to compress in 3.3 than when using the 2.5 series. This release also fixes one reported stability issue.

* **General:**
* **Feature:** Normal map image quality has been improved.
* **Feature:** Two component image quality has been improved, provided that unused components are correctly zero-weighted using e.g. `-cw` on the command line.
* **Bug-fix:** Improved stability when trying to compress complex blocks that could not beat even the starting quality threshold. These will now always compress in to constant color blocks.

Binary release sha256 checksums


d686330476b104b94ff74eadc79b1778bf36aa42eb6f3904dca36af05a4c8c87 astcenc-3.3-linux-x64.zip
0b9eb51e75a433e68b5f8659d95b6e315b12a2263617beb2bca4cc5fbd396c00 astcenc-3.3-macos-aarch64.zip
c7f150dc54bd26f177cc94dd9531c2f9ec94f419047d943be8822d9d62e2e65e astcenc-3.3-macos-x64.zip
71644196c3e8a9205844fbf407e9f41df1911c787ac055b664307b60c3e9155d astcenc-3.3-windows-x64.zip