v0.20.0

pixtreme-transport 0.20.0: the entrance conversion and the exit serialization take their colour definitions from pixtreme, YCbCr Frames carry Cb and Cr centred at 0, the native ABI becomes 7 and CONFORMANCE_REVISION becomes 8. The core now requires pixtreme>=2.2.2 at build and run time.

• Colour definitions: the core resolves colour coefficients (chromaticities, white points, conversion matrices between colorspaces, the YCbCr Kr and Kb, and the mapping between codes and Frame values) through pixtreme's colour C interface at run time, and uses the CUDA device helpers that pixtreme ships for the pixel computations. The core's native library depends on pixtreme's shared library libpixtreme.so.2 and finds it in the installed pixtreme wheel through a relative $ORIGIN RPATH.
• Chroma centre: floating-point YCbCr Frames carry Cb and Cr centred at 0, matching pixtreme 2.2. The entrance writes, and the exit reads, Cb and Cr on that scale. Code-grid quantization is otherwise unchanged.
• Native ABI 7: libpixtreme_transport.so.7. C++ modules that use the core's public native ABI must be rebuilt against the 0.20.0 headers; the ABI check rejects a module built for ABI 6.
• Conformance suite: pixtreme.transport.CONFORMANCE_REVISION is 8. Expected values that depend on the chroma centre follow the 0-centred scale. A module that pins the expected suite revision changes that value to 8 when it moves to this version.
• Dependency: pixtreme>=2.2.2. pixtreme 2.2.1 can deadlock when the exit's native thread calls pixtreme's C interface while a Python thread holding the GIL waits for it (sync-dev-org/pixtreme-dev#231); 2.2.2 fixes this.
• Known limitation: while Python does not call pixtreme and only the core's native threads call pixtreme's C interface, Python owners that pixtreme borrowed stay queued until a later Python call runs pixtreme's owner cleanup (for example px.core.memory_info()). This is tracked by pixtreme (sync-dev-org/pixtreme-dev#233).
• Wheels: CPython 3.12 and 3.13, manylinux_2_28_x86_64, built with the image pixtreme-transport-wheel:cuda13-manylinux_2_28-d4816d03a6ff from wheel-build/ at this tag (CUDA 13.2). Each wheel ships the shared library libpixtreme_transport.so.7, the public C and C++ headers, the CMake package configuration and the testing package. The GPU code targets sm 86, sm 89 and sm 120, with compute 120 PTX. CUDA's runtime is linked statically; neither the NVIDIA driver library nor pixtreme's shared library is included.
• Verify the assets with sha256sum -c SHA256SUMS.