What is SCTE-35 and how does it work?
If you watched television in the early 2000s, you may remember hearing dial tones before commercial breaks, or experiencing a long delay before the commercials started. What you probably didn't know is that those tones were actually an early form of SCTE-35 messaging. Broadcasting has come a long way, but the SCTE-35 standard remains essential. Discover what SCTE-35 is, how it works, and its benefits here.
What is SCTE-35?
SCTE-35 is a set of standards that regulates where and how markers — also known as cue messages — are inserted into live broadcasting streams. The markers are in-stream messaging mechanisms that indicate when the content can be spliced. They can be used for both advertisements and other content, like half-time or intermission commentary in live sports.
In this article we’ll mainly refer to SCTE-35 in the context of ad markers. The standard created both static ad markers — which are used in traditional broadcast channels, including satellite — and dynamic ad markers, which are typically used in live streaming and other IP-based media.
What does SCTE-35 stand for?
The abbreviation SCTE-35 represents standard number 35 developed by the Society of Cable and Telecommunications Engineers (SCTE). The full name of the standard is "Digital Program Insertion Cueing Message for Cable." It was first released in 2001 as a way to streamline the insertion of ads into cable broadcasts using videotape players. The standard has been continuously updated since then as the popularity of the internet increased and traditional television broadcasts switched from analog to digital transport streams.
SCTE-35 vs. 104
SCTE creates a variety of standards — governing everything from internet protocols to video compression to communication. SCTE-104 is another standard that involves television broadcasting cue messages; however, it applies to the systems and equipment within the broadcast facility itself. Here are the main differences:
SCTE-35 focuses on the downstream insertion of markers within a video file. It signals the start and end points for programs, commercials, network logos, and other information needed for targeted content delivery to the end user.
SCTE-104 is used to pass messages between systems and equipment in the television broadcast facility. It helps the equipment exchange information related to switching, encoding, and monitoring.
Key components of SCTE-35 messaging
The markers inserted into a video stream are the foundation of the SCTE-35 standard. So, when someone asks “What is SCTE-35?,” what they often really want to know is: what are these ad markers, and how do they work? SCTE-35 messaging can be broken down into several related parts:
Cue message: This message serves signals when and where an ad insertion point should occur within the video stream. It contains essential information such as the splice type (whether it's a simple splice, a splice with a duration, etc.), the precise timing of the splice, and additional descriptors that help synchronize the content.
Splice information section (SIS): The SIS is a part of the cue message that conveys detailed information about the splice event. It includes parameters like the unique identifiers for the content being replaced and inserted, and the duration of the splice.
Time signal: SCTE-35 utilizes Coordinated Universal Time (UTC) as a reference for synchronization. The time signal provides the necessary information to ensure that ad insertion points align accurately across different systems and platforms.
Key components of SCTE-35 messaging
The markers inserted into a video stream are the foundation of the SCTE-35 standard. So, when someone asks “What is SCTE-35?,” what they often really want to know is: what are these ad markers, and how do they work? SCTE-35 messaging can be broken down into several related parts:
Cue message: This message serves signals when and where an ad insertion point should occur within the video stream. It contains essential information such as the splice type (whether it's a simple splice, a splice with a duration, etc.), the precise timing of the splice, and additional descriptors that help synchronize the content.
Splice information section (SIS): The SIS is a part of the cue message that conveys detailed information about the splice event. It includes parameters like the unique identifiers for the content being replaced and inserted, and the duration of the splice.
Time signal: SCTE-35 utilizes Coordinated Universal Time (UTC) as a reference for synchronization. The time signal provides the necessary information to ensure that ad insertion points align accurately across different systems and platforms.
How SCTE-35 ad markers work
SCTE-35 triggers are encoded into video streams’ metadata at the origination point, so that downstream receivers know where the program content ends and ads can begin. When the stream hits one of these markers, it automatically triggers the seamless insertion of an ad or other predetermined content. Here’s how it works:
Initiation: The broadcaster decides to insert an ad into the video stream, often using automated technologies to do so. The content delivery system generates a cue message containing the relevant information about the splice event
Transmission: The cue message is transmitted within the video stream to downstream devices, such as demand-side platforms, encoders, multiplexers or ad splicers
Insertion: When the video stream reaches the designated point, the cue message triggers the ad splicer or other software to seamlessly replace the main content with the ad content
Synchronization: The use of UTC in the time signal ensures that the ad insertion occurs precisely at the intended moment, maintaining synchronization across various devices and networks
Benefits of SCTE markers in television
Whether you're using SCTE-35 messaging to insert dynamic, personalized ads or to stitch together pre- and post-game shows for different markets, these markers have undeniable benefits.
Improved user experience
When SCTE-35 was first developed in the age of analog television, ad markers were simply audio tones that signaled to downstream VHS tape players when to start and stop advertisements. While this allowed for some flexibility in the content — for example, inserting regional ads — the user experience still had a long way to go.
Today, viewers expect a seamless experience across channels and platforms. SCTE-35 markers help deliver on that expectation by allowing broadcasters to smoothly transition a program to another type of content and back again without pauses or interruptions. They allow for greater personalization and can even be used to mark the beginning of a program, like a sporting event, so that viewers can start from the beginning even if they were late tuning in. All of this enhances the viewing experience.
Operational efficiency
Original SCTE-35 markers were widely embraced because they didn't require any new hardware or systems. But they had plenty of limitations, including a lack of personalization and a need for manual insertion. As digital TV signals began to replace analog, broadcasters found more opportunities that not only improved the downstream experience but also helped them achieve operational excellence.
The SCTE-35 standard enables highly automated workflows that take on some of the legwork that traditionally fell to broadcast operators. Modern technology can automatically insert ad triggers, find the best ad bids, manage content updates, and stitch it all together with minimal human oversight. That not only improves efficiency, but also reduces errors.
Content monetization
From its very early days, television broadcasting has always been reliant on advertising revenue. While viewers now watch programming through digital and OTT channels rather than traditional cable or satellite, the challenge remains the same. SCTE-35 messaging can help you optimize your advertising revenue and monetize your content in other ways as well — for example, through live event versioning that creates hyper-personalized programming distributed through an app.
Get the most from SCTE-35 with LTN Arc
Now that you know what SCTE-35 is, you need to ask yourself: Are you maximizing its potential? To answer that question with a “yes,” you need to scale your ad break, content replacement, and video distribution workflows in ways that drive revenue growth. LTN Arc can help by ingesting undecorated video, inserting multiple SCTE-35 markers, watermarks, and other metadata, then seamlessly transmitting multiple feeds downstream.
LTN Arc doesn't stop with advanced SCTE-35 signaling. Through our proprietary technology, a single operator in our always-on technical operations center can take care of versioning, feed decoration, audio management, and more for four times as many feeds as legacy workflows Simplify your operations and improve your user experience today. Contact us for a demo to see what we can do for you.