Skip to main content
Version: v2.3.0

SCTE-35

Introduction​

SCTE-35 is a standard used in the broadcasting industry for signaling the insertion of non-program material such as advertisements or other content. It plays a crucial role in Dynamic Ad Insertion (DAI) for live streaming. This documentation aims to provide an overview of SCTE-35 and it's integration into Bitstreams.

warning

Bitstreams currently does not support generating DASH manifest files with SCTE-35 signals. Only HLS manifest files are supported.

Understanding SCTE-35​

SCTE-35 markers are timed metadata used to signal ad opportunities or other events within a video stream. These markers indicate the precise timing for when an ad can be inserted and its duration. The process involves the use of cue points, which are specific timestamps in a stream that signal the start or end of an ad insertion opportunity.

Key Concepts​

  • Cue Points: Specific timestamps within a video stream that signal the start or end of an ad insertion opportunity.
  • IDR Frames: Instant Decoder Refresh frames that allow a video player to start playback at any given point without needing the video data that came before.
  • Splice Points: The actual points in a video stream where content can be inserted or replaced seamlessly.

Implementing SCTE-35 in Live Streaming​

Workflow Overview​

  1. Signal Ad Opportunities: SCTE-35 markers are used to signal ad insertion opportunities within the live stream.
  2. Ingest SCTE-35 Markers: Bitstreams ingests these markers as part of the metadata track.
  3. Generate Client Manifests: Bitstreams generates HLS client manifests with the ad signaling included.
  4. Playback: The modified manifest is then served to the end-user's player, which requests the ad content at the appropriate time.

Technical Implementation​

When an incoming stream includes SCTE-35 markers, Bitstreams will do the following:

  • Pass SCTE-35 events from MPEG-TS to HLS
  • Generate IDR at SCTE-35 event
  • Create a new segment at SCTE-35 event

Signaling in Client Manifests​

For HLS:

  • Use EXT-X-DATERANGE for signaling cue points.
  • Use EXT-X-CUE-OUT and EXT-X-CUE-IN for marking the ad's start and end.

Example​

HLS Manifest Snippet:

#EXTINF:8,
audio=70000-video=105000-000001.ts
#EXT-X-PROGRAM-DATE-TIME:2023-09-12T21:42:24Z

#EXTINF:8,
audio=70000-video=105000-000002.ts
#EXT-X-PROGRAM-DATE-TIME:2023-09-12T21:42:32Z

#EXT-X-DATERANGE:ID="188",START-DATE="2023-09-12T21:42:40Z",PLANNED-DURATION=24,SCTE35-OUT=0xFC302200000000000000FFF02006000000CC8FEF8F8E0030F680000000000000642D9BDF
#EXT-X-CUE-OUT:24

#EXTINF:8,
audio=70000-video=105000-000003.ts
#EXT-X-PROGRAM-DATE-TIME:2023-09-12T21:42:40Z