I want to get spatial videos in HEVC format, but after sharing to the share extension, I found that the video was automatically transcoded to AVC format.

I can only download usdpython from following website: https://developer.apple.com/augmented-reality/tools/ And where could I get the various versions of the usdpython? Is the usdzconvert(usdpython) of Apple open source? Because I wanna learn how Apple achieves the conversion from GLTF to USDZ because I'm currently using version 0.66, and I feel that the conversion of GLTF features is not quite sufficient.