What does SCTE35 tags/marker do? How hls parse the SCTE35-CMD?

Question

My question is what's the difference in SCTE35-IN , SCTE35-OUT, and in SCTE35-CMD ?

Answer 1

HLS EXT-X-DATERANGE tags that carry SCTE-35 use these attributes.

For SCTE-35 Splice Insert Commands and Time Signal commands that are used to signal an ad splice:

The SCTE35-OUT attribute is used to indicate the START of an ad break,

The SCTE35-IN attribute is used to indicate the END of an ad break,

For SCTE-35 Commands that don't signal an ad break ( Splice Null, Bandwidth Reservation, Splice Schedule, and some Time Signals), the SCTE-35-CMD attribute is used.

the value for SCTE35-OUT, SCTE35-IN, and SCTE35-CMD is the SCTE-35 Cue messsage in hex instead of the usual base64.

Answer 2

This is well documented in the HLS specification: https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis-11#section-4.4.5.1.1.

The contents of SCTE35-CMD are as described in the SCTE35 specification, currently available to download with no cost at https://www.scte.org/standards/library/catalog/scte-35-digital-program-insertion-cueing-message/.