SCTE-35 is the standard for signaling ad-break opportunities (and other timed events) inside a stream. It tells downstream systems exactly where an ad can be inserted — the start and duration of an avail, the splice points, and metadata identifying the break — originally for cable ad-insertion and now the backbone of OTT ad insertion as well.
In a streaming pipeline, SCTE-35 markers ride in the transport (and are surfaced into HLS tags or DASH events in the manifest) so the packager and the ad inserter know when a break is coming and can align segment boundaries to it. SSAI uses these markers to decide where to stitch ads; client-side systems use the manifest-level signals to trigger ad requests.
Accurate SCTE-35 is what makes frame-precise, seamless ad insertion possible, especially for live and linear where breaks occur in real time. Mis-timed or missing markers cause missed ad revenue, content clipping, or jarring transitions — so conditioning and validating SCTE-35 is a real operational concern.
