Quadra supports passthrough of user data unregistered SEI payloads during transcoding for H.264 and H.265. This can be enabled by specifying the decoder codec parameter user_data_sei_passthru as per the following example:
ffmpeg -c:v h264_ni_quadra_dec –user_data_sei_passthru 1 -i input.264 -c:v h265_ni_quadra_enc output.265
This feature is intended for passing through small user data unregistered SEI messages up to 1024 bytes in size. For larger SEI messages please use the custom_sei_passthru option. For more details on user data passthrough please see the SEI Passthrough Application Note.