What is a SCTE-35 marker and how is it used in CTV advertising?

SCTE-35 (Society of Cable and Telecommunications Engineers standard 35) is a digital cue signalling protocol used to mark ad break insertion points in video streams. A SCTE-35 marker is an embedded signal in the video bitstream that says "an ad break starts here and lasts N seconds." For CTV SSAI delivery, the SCTE-35 marker is what triggers the ad server to splice ads into the content stream at the right moment. Without SCTE-35 markers, the SSAI platform would not know when or where to insert ads in a live or on-demand stream. In India CTV, SCTE-35 is used by publishers that operate SSAI delivery — primarily JioHotstar for its live sports and premium VOD content.

When a live stream (e.g., an IPL match on JioHotstar) approaches an ad break, the content encoder inserts a SCTE-35 splice_insert message into the bitstream specifying the break duration. The SSAI platform (AWS MediaTailor, or JioHotstar's proprietary equivalent) detects this signal and makes an ad request to the ad server for a pod of ads matching the break duration. The ad server returns the winning creatives; the SSAI platform stitches them into the stream at the marked break point. The viewer experiences a seamless transition from content to ads and back. For CSAI delivery (most non-JioHotstar India publishers), SCTE-35 markers are less relevant — break points are signalled through the app's own logic rather than stream-embedded cues.

Buyers do not configure SCTE-35 markers — that is the publisher's and broadcaster's responsibility. However, understanding SCTE-35 helps buyers diagnose two specific problems: (1) If a live CTV campaign on JioHotstar delivers fewer impressions than expected during a live event, incorrect SCTE-35 signalling (missed markers, wrong break durations) on the encoder side can cause the SSAI system to miss break points — resulting in ads never being inserted. This is a publisher-side issue; raise it with the JioHotstar programmatic team. (2) Break duration mismatches — if a SCTE-35 marker signals a 30-second break but only a 15-second slot is available, a 30-second creative will not serve. Always confirm break durations with the publisher and provide creatives in matching lengths.