Based on the SCTE 35 2023r1 standard from Digital Program Insertion Cueing Message — SCTE, FFmpeg 6.1 has been extended to support
Decoding of SCTE 35 data to force keyframes on Cue Out and Cue In
SCTE 35 markup in HTTP Live Streaming (HLS) playlist using EXT-X-SCTE35
Decoding logic is currently limited to the following:
splice_insert()
splice_event_cancel_indicator 0
out_of_network_indicator 0 or 1
duration_flag 0 or 1
If duration_flag is set for CUE OUT, a CUE IN will be added based on auto_return and duration and any subsequent CUE IN will be ignored
program_splice_flag 1 and splice_immediate_flag 0