Hi,
This is enabled on Jetpack 5.1.1(r35.3.1). Please upgrade to the release and try the commands on AGX Orin or Orin NX:
01_video_encode$ gst-launch-1.0 videotestsrc num-buffers=500 ! video/x-raw,width=1920,height=1080 ! filesink location=~/a.yuv
01_video_encode$ ./video_encode ~/a.yuv 1920 1080 AV1 ~/a.av1 -br 8000000 --report-metadata -rpc "f250,b4000000"
01_video_encode$ ./video_encode ~/a.yuv 1920 1080 AV1 ~/a.av1 -br 8000000 --report-metadata -rpc "f250,r60/1"