This addon (script.module.sidedata) is licensed GPL-2.0-or-later as a whole.
lib/sidedata/native.py binds to a libdovi.so build through ctypes.CDLL at runtime and calls straight into it. All Dolby Vision RPU bitstream parsing is done by that library, not by this addon (see README.md).
lib/sidedata/native_libs/aarch64/libdovi.so is an unmodified compiled build of libdovi 3.4.0 (MIT, quietvoid, https://github.com/quietvoid/dovi_tool), built from the libdovi-3.4.0 tag of dovi_tool's dolby_vision crate per tools/build-libdovi.sh, and is distributed with this addon on that architecture. Other architectures fall back to a platform-provided libdovi.so, loaded at runtime with nothing distributed, and there is no bundled fallback parser for those.
native.py itself contains no dovi_tool code beyond struct layouts and function signatures transcribed from its public C header (libdovi/rpu_parser.h) so ctypes can call into it correctly. The MIT license terms apply equally to the bundled binary and this binding. The license text and copyright notice are reproduced in LICENSES/dovi_tool.MIT.
lib/sidedata/avutil.py binds to CoreELEC's own libavutil.so (part of FFmpeg, LGPL-2.1-or-later) through ctypes.CDLL at runtime and calls av_dynamic_hdr_plus_from_t35 directly. All HDR10+ (ST 2094-40) T.35 parsing is done by that library, not by this addon.
avutil.py declares ctypes structs transcribed from FFmpeg 8.1.2's public header (libavutil/hdr_dynamic_metadata.h), unchanged in FFmpeg 9.0, the versions CoreELEC 22 has shipped, so ctypes can call into it correctly, gated on a matching avutil_version() major (see README.md's "Parsing engines"). No FFmpeg code is vendored or linked, and nothing is distributed with this addon for this path. libavutil.so is always CoreELEC's own copy.