SCTE-35

What is SCTE-35?

SCTE-35 is a signaling standard used in digital video streams to mark points where content—typically advertisements or local programming—can be inserted. These markers are embedded in MPEG transport streams (MPEG-TS) and allow downstream systems to identify precise cue points for dynamic ad insertion, program replacement, or blackout enforcement.

SCTE-35, formally known as ANSI/SCTE 35, is a standard developed by the Society of Cable Telecommunications Engineers. It defines a method for inserting metadata cues in broadcast or streaming video to indicate events such as ad breaks, program transitions, or regional content substitutions.

These cues do not carry the replacement content themselves; instead, they act as markers that signal when and where new content can be inserted by downstream systems such as playout servers, ad servers, or distribution partners.

How Does SCTE-35 Work?

SCTE-35 messages are embedded within MPEG-TS video streams and are typically used in both live and linear video workflows. When a cue message is received, compatible systems can take action based on the metadata provided—such as triggering an ad insertion or switching to alternate content.

Each SCTE-35 cue contains information such as:

Event start and duration

• Splice type (e.g., program or ad break)
• Unique identifiers
• Optional segmentation descriptors

These messages allow for frame-accurate transitions and are essential for maintaining viewer experience during content changes.

Role of SCTE-35 in Streaming TV

In the streaming ecosystem, SCTE-35 is widely used in Free Ad-Supported Streaming TV (FAST) channels, live streaming, and Connected TV (CTV) environments. It enables:

• Dynamic Ad Insertion (DAI): Replacing broadcast ads with personalized or programmatic ads.
• Regional blackout enforcement: Restricting content in certain geographic areas.
• Seamless content switching: Enabling program transitions without disrupting the stream.

Cloud-based streaming platforms often convert SCTE-35 markers into other formats compatible with IP-based workflows, such as SCTE-104 or ad decisioning APIs.

Industry Importance

SCTE-35 is a foundational element in automated, scalable content distribution. It allows broadcasters, streaming platforms, and advertisers to deliver more personalized and flexible viewing experiences. Without SCTE-35 or equivalent cueing systems, targeted advertising and live stream customization would be significantly more difficult to implement.

As streaming continues to evolve, SCTE-35 remains an essential standard for supporting monetization, compliance, and content localization across linear and IP-based video workflows.