When a CTV or FAST channel reaches an advertising break, something needs to tell the downstream video system that an ad opportunity is available. In many live streaming workflows, that signal is carried using SCTE-35.
This page explains the process from the original ad-break marker through the SSAI or CTV platform, the ad-server request, the VAST response and the final advertising break.
SCTE-35 says “there is an ad opportunity here.” Your SSAI or streaming system detects that opportunity and requests an advertisement. The ad server decides which ad should run and returns the advertising response, typically VAST.
SCTE-35 is signaling. It is not the advertisement itself. The marker tells downstream systems that something is supposed to happen at a particular point in the stream. Streaming infrastructure then turns that opportunity into an ad-serving request.
The channel is transmitting a normal program.
An ad opportunity is signaled.
The system detects the opportunity.
Campaigns are evaluated and an ad decision is made.
The selected creative and tracking information are returned.
SCTE-35 is a standard used to signal events in television distribution and streaming workflows. For advertising, the signal can identify a placement opportunity, the start or end of a break, and additional information that downstream systems can use.
A splice_insert() SCTE-35 message can be used
to signal an insertion opportunity and may include timing
and duration information. This is one of the common methods
supported by streaming ad-insertion systems.
A time_signal() message can be combined with
a segmentation_descriptor() to communicate
more detailed information about the event, such as the
type of opportunity and its duration.
| Concept | What it means | Why it matters for CTV advertising |
|---|---|---|
SCTE-35
|
Signaling information carried with a video workflow. | Lets downstream systems know that an event such as an advertising opportunity has occurred. |
splice_insert()
|
A SCTE-35 command used to signal an insertion event. | Can provide the basic timing information needed to identify an ad opportunity. |
time_signal()
|
A timed SCTE-35 event. | Can be combined with segmentation metadata for more detailed ad-break signaling. |
segmentation_descriptor()
|
Metadata associated with a SCTE-35 event. | Can identify the type, timing and other characteristics of the opportunity. |
Video packaging systems can represent SCTE-35 information
in output manifests. In HLS, one common representation is
EXT-X-DATERANGE. Another is the SCTE-35 enhanced
cue format using EXT-X-CUE-OUT,
EXT-X-CUE-OUT-CONT and
EXT-X-CUE-IN.
The exact representation depends on the streaming platform and its configuration.
Once an SSAI or other ad-insertion system recognizes the advertising opportunity, it needs an ad decision. This is where the ad server enters the workflow.
The live stream reaches the point identified by the SCTE-35 signal as an advertising opportunity.
The streaming system interprets the marker and determines that an advertisement should be requested.
The streaming infrastructure requests an advertising decision. Depending on the implementation, the request can contain information about the channel, placement, stream, session and other available context.
The ad server checks which direct campaigns are eligible at that moment. Campaign dates, targeting, pacing, priorities, frequency rules and available creatives can all influence the decision.
The selected advertisement is returned in a VAST response. The response identifies the creative and can contain media files, impression tracking and playback-event tracking information.
The surrounding streaming infrastructure retrieves, processes and prepares the advertisement according to its own workflow before inserting it into the stream.
The viewer experiences the advertisement as part of the stream rather than as a separate browser-style ad request. When the break ends, playback returns to the program.
A CTV commercial break may have enough available time for multiple advertisements. Instead of returning one creative and ending the decision, the ad-serving workflow can select a sequence of ads that fits the available break.
The precise behavior of an ad pod depends on the ad server and the SSAI platform. The important concept is that the SCTE-35 signal identifies the opportunity; the ad-serving layer decides what advertising should fill that available time.
A channel owner does not need to use programmatic advertising for every ad break. Many channels sell sponsorships and campaigns directly to brands, agencies or advertisers.
The channel owner has already agreed on the advertiser, campaign dates, inventory and commercial terms. The ad server's job is to deliver that campaign according to the booking.
When the stream signals a break, the ad server determines which eligible direct campaigns should occupy the available inventory.
SSAI and the ad server have different jobs. The SSAI system is responsible for combining advertisements and program content into the streaming delivery workflow. The ad server is responsible for deciding what advertisement should be returned for an opportunity.
Produces the live program.
Signals the ad opportunity.
Detects the break and requests an ad.
Makes the campaign decision and returns VAST.
Viewer receives program + advertising.
A successful CTV ad break depends on several systems working together. The marker, break timing, ad request and returned creative all need to fit the available opportunity.
The downstream system may never know that an ad opportunity exists, so no advertising request is triggered.
Available inventory may not be sufficient for the selected creative or pod. The exact behavior depends on the streaming and ad-insertion platform.
The ad server may have no campaign satisfying the targeting, timing, pacing or other delivery conditions for that request.
A creative may fail because of duration, media format, transcoding, VAST errors or platform-specific requirements.
| Term | Simple explanation |
|---|---|
| SCTE-35 | Signaling used in broadcast and streaming workflows to identify events such as advertising opportunities. |
| SCTE-35 OUT | A signal indicating the beginning of an opportunity or break. |
| SCTE-35 IN | A signal indicating the return to normal program content. |
| CUE-OUT | An HLS manifest representation commonly used to indicate the beginning of an ad break. |
| CUE-IN | An HLS manifest representation commonly used to indicate the end of an ad break. |
| SSAI | Server-side ad insertion: advertisements are combined with streaming content on the server side. |
| VAST | A standard XML-based format used to communicate video advertising information from an ad server to an advertising playback or insertion system. |
| Ad pod | A sequence of multiple advertisements occupying one commercial break. |
CTVBreak is a CTV ad server used by channel owners, publishers, broadcasters and FAST operators to manage direct-sold advertising campaigns. In a typical live CTV or FAST workflow, a video stream contains signaling that identifies an advertising opportunity. SCTE-35 is one standard used for this purpose.
A useful conceptual model is: SCTE-35 signals the opportunity → SSAI detects it → the ad server makes the advertising decision → VAST describes the advertisement → SSAI delivers the ad within the stream.
No. SCTE-35 is signaling. It tells downstream systems about an event or advertising opportunity. The advertisement is obtained separately through an ad-serving workflow.
No. CTV architectures vary. SCTE-35 is widely used in professional live television and streaming workflows, but the exact signaling method depends on the platform and distribution architecture.
It receives or processes an ad request, evaluates eligible campaigns, selects the appropriate advertisement and returns an advertising response such as VAST.
Yes. A CTV ad pod can contain multiple advertisements. The available break duration determines how many ads can fit and the ad-serving workflow determines which eligible ads are selected.
No. SSAI handles server-side insertion and streaming delivery. An ad server handles campaign management and ad decisioning. The two systems commonly work together.
Yes. A channel can sell advertising directly to brands or agencies and use an ad server to deliver those booked campaigns when ad-break opportunities occur.
A focused ad server for direct advertising relationships - not an exchange, not programmatic infrastructure, and not more complexity than you need.
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