The Decoder API is defined in https://github.com/Xilinx/vdu-ctrl-sw/blob/xlnx_rel_v2023.1/include/lib_decode
The API is documented with Doxygen and it can be access by browsing the
vdu-ctrl-sw/Doxygen/doc/html/index.html.
The example application ctrlsw_decoder demonstrates how to use the API.