Hi,
We suggest call NvBufferTransform() for the conversion. It is done on the hardware converter VIC. If you use CUDA the loading is moved to GPU.
If you would like to move the conversion to GPU, there is no existing sample for YUV422 to YUV420 conversion. Some samples for converting to BGR/RGBA:
jetson-utils/cuda at 1ee0494b196b488b4b95e89fa2d72366d3cf4879 · dusty-nv/jetson-utils · GitHub