Signaling: How to Optimize OTT Streams with EPG, SCTE-35, and Manifest Manipulation

OTT (Over-The-Top) streaming has evolved rapidly, offering more interactive and dynamic viewing experiences. However, to maximize usability, compatibility, and monetization, integrating proper signaling into your streams is crucial. Signaling ensures precise timing, synchronization, and metadata delivery, making it an essential component for broadcasters and service providers.

The Role of Signaling in OTT Streaming

• Electronic Program Guide (EPG) Integration – Allowing viewers to see upcoming content, schedules, and program information.
• Content Synchronization – Ensuring smooth transitions between content, accurate ad insertion, and seamless playback across devices.
• Ad Insertion (SCTE-35 Markers) – Providing cue points for dynamic ad insertion (DAI) in both live and VOD streams.
• Time Alignment (PROGRAM-DATE-TIME) – Synchronizing timestamps for cross-device consistency and accurate playback.
• Manifest Manipulation – Dynamically modifying playlists for targeted content delivery, personalized experiences, and compliance with regional restrictions.
• Startover and Timeshifting Features – Allowing users to restart a live program from the beginning or rewind content as needed.

Key Signaling Mechanisms

1. Electronic Program Guide (EPG)

An EPG allows users to browse scheduled programming, similar to traditional broadcast TV. It relies on metadata signaling to map content descriptions, start times, and durations.

2. SCTE-35 for Ad Insertion

SCTE-35 markers provide essential cues for server-side and client-side ad insertion. They enable dynamic ad replacement without interrupting the viewer's experience. Proper implementation allows:

• Seamless ad insertion without buffering or delays.
• Better monetization through targeted advertising.
• Compliance with regional ad regulations.

3. PROGRAM-DATE-TIME for Timestamping

The PROGRAM-DATE-TIME tag in HLS playlists ensures precise timing for synchronization between live broadcasts and OTT streams. This is particularly important for:

• Live sports events and news broadcasts.
• Synchronizing multi-camera feeds and interactive elements.
• Ensuring consistency in analytics and reporting.

4. Manifest Manipulation for Personalized Streaming

Manifest manipulation allows dynamic changes to an HLS or DASH manifest, enabling:

• Personalized ad insertion.
• Content replacement based on user preferences or geographical restrictions.
• Dynamic bitrate adaptation beyond standard ABR (Adaptive Bitrate) logic.

5. Startover and Timeshifting

Startover and timeshifting features improve user experience by providing greater control over live content. These functionalities rely on metadata signaling and manifest manipulation:

• Startover TV – Enables users to restart a live program from the beginning, even if they joined late.
• Timeshifting – Allows viewers to pause, rewind, and resume live broadcasts, enhancing flexibility.
• Catch-up TV – Provides access to past programs within a predefined window, often leveraging manifest updates.

Debugging with Custom Signaling Tags

To ensure a seamless streaming experience, custom signaling tags can be integrated for debugging purposes. These tags help identify specific playback issues, ad insertion points, and metadata synchronization errors. Benefits include:

• Tracking performance bottlenecks in live and VOD streams.
• Providing unique identifiers for content segments to detect mismatches.
• Enabling more granular logging for troubleshooting inconsistencies in manifest manipulation.

Implementing Signaling in Your OTT Workflow

1. Ensure Proper Metadata Injection – Work with your encoder and packager to insert EPG data, SCTE-35 markers, and time metadata.
2. Use a Server-Side Ad Insertion (SSAI) System – If implementing SCTE-35, an SSAI solution will handle ad replacement seamlessly.
3. Optimize Manifest Manipulation – Use open-source manifest manipulation solutions or custom server-side logic to modify playlists dynamically.
4. Monitor and Test Streams Regularly – Validate signaling accuracy with tools like ffprobe, HLS Analyzer, or commercial monitoring solutions.

Signaling is a critical component of modern OTT streaming, enhancing synchronization, monetization, and user experience. By integrating EPG data, SCTE-35 markers, PROGRAM-DATE-TIME, manifest manipulation, and features like startover and timeshifting, broadcasters can optimize their streams for both viewers and advertisers. Implementing these strategies ensures seamless playback, precise ad targeting, and better content discoverability—key factors in the competitive OTT landscape.

Article written by
Sylvain Corvaisier

Independent streaming and iOS engineer

Last modified: February 25th, 2025