• Houdini 21.0 targets the VFX Platform CY2025 specification (https://www.vfxplatform.com).

• Replaced TBB 2020 with oneTBB 2022.

• Replaced MKL 2020 with oneMKL 2025, Linux and Windows only. macOS continues to use MKL because oneMKL 2025 is not available on Mac. The MKL and oneMKL libraries are statically linked into Houdini with their symbols hidden.

• Upgraded Boost to 1.85.0.

• Upgraded NumPy to 1.26.4.

• Upgraded OpenColorIO to 2.4.1.

• Upgraded OpenEXR to 3.3.2.

• The main Houdini builds are now on Qt 6.5.3. Separate Qt 5.15.2 build are available for download.

• Python 3.10 is no longer supported.

• Intel Mac (x86_64) builds are deprecated. The Houdini 21.0 Intel Mac builds are fully supported but the builds will no longer be available in a future Houdini major or minor version release.

• Floating windows no longer disappear when Houdini loses focus on macOS. This applies to windows that float on top when the General User Interface → Keep Floating Windows on Top preference is checked on.

• MPlay can now encode .mov files with the ProRes codec.

The minimum x86-64 architecture level for Linux and Windows to run Houdini is now v3. This lets us use many more features that are provided in modern processors such as AVX, AVX2, and hardware-based half-precision floating point support. In order to take advantage of newer features, we need to drop support for some older processors.

For more information, see Houdini system requirements.

Houdini 21 includes a number of optimizations that greatly reduce filesystem activity. This has resulted in the following improvements:

• Greatly reduced startup time on certain Windows systems

• Greatly reduced filesystem activity when loading Houdini

• Upgraded FFmpeg to 7.1.0.

• Upgraded OpenImageIO to 2.5.18.0.

• Upgraded OpenShadingLanguage to 1.13.12.0.

• Upgraded SVT-AV1 to 3.0.0.

• Upgraded dav1d to 1.5.1.

• Upgraded kvazaar to 2.3.1.

• Upgraded libvpx to 1.15.0.

• Upgraded openh264 to 2.6.0.