SCTE-35 messages for ad breaks - AWS Elemental MediaTailor

SCTE-35 messages for ad breaks

With MediaTailor, you can create a content channel based off of source location and VOD source resources. You can then set up one or more ad breaks for each of the programs on a channel's schedule. You use messages based on the SCTE-35 specification to condition the content for ad breaks. For example, you can use SCTE-35 messages to provide metadata about the ad breaks. For more information about the SCTE-35 specification, see Digital Program Insertion Cueing Message.

You set up the ad breaks in one of two ways:

  • Attaching a time_signal SCTE-35 message with a segmentation_descriptor message. This segmentation_descriptor message contains more advanced metadata fields, like content identifiers, which convey more information about the ad break. MediaTailor writes the ad metadata to the output manifest as part of the EXT-X-DATERANGE (HLS) or EventStream (DASH) ad marker's SCTE-35 data.

  • Attaching a splice_insert SCTE-35 message that provides basic metadata about the ad break.

  • HLS:

    • When the Ad markup type is Daterange, MediaTailor specifies ad breaks as EXT-X-DATERANGE tags in the manifest.

    • When the Ad markup type is Scte35 Enhanced, MediaTailor specifies ad breaks using the following tags:

      • MediaTailor places an EXT-X-CUE-OUT on the first segment of the ad slate, indicating a cut from content to the ad break. It contains the expected duration of ad break, such as EXT-X-CUE-OUT:Duration=30.

      • >EXT-X-ASSET: This tag appears on the same segment as EXT-X-CUE-OUT and contains the ad-break metadata supplied in the AdBreak when the program is created or updated. It always contains CAID.

      • EXT-OATCLS-SCTE35: This tag appears on the same segment as EXT-X-CUE-OUT and contains base64-encoded bytes of the SCTE-35 message.

      • EXT-X-CUE-OUT-CONT: This tag appears on each subsequent segment within the ad slate, and contains duration and elapsed-time information. It also contains the base64-encoded SCTE-35 message, and the CAID.

      • EXT-X-CUE-IN: This tag appears on the first segment of content after the ad break is over, and indicates a cut from an ad break back to content.

The following illustration shows the two ways of setting up ad breaks in a channel using SCTE-35 messages:

  • Use a splice_insert() message to set up ad breaks with basic metadata.

  • Use a time_signal() message together with a segmentation_descriptor() message to set up ad breaks with more detailed metadata.

Two ways of setting up ad breaks in a channel using SCTE-35 messages.

For information about using time_signal, see section 9.7.4 of the 2022 SCTE-35 specification, Digital Program Insertion Cueing Message.

The ad break information appears in the output splice_info_section SCTE-35 data. With MediaTailor, you can pair a single segmentation_descriptor message together with a single time_signal message.

Note

If you send a segmentation_descriptor message, you must send it as part of the time_signal message type. The time_signal message contains only the splice_time field that MediaTailor constructs using a given timestamp.

The following table describes the fields that MediaTailor requires for each segmentation_descriptor message. For more information, see section 10.3.3.1 of the 2022 SCTE-35 specification, which you can purchased at the ANSI Webstore website.

Required fields for a segmentation_descriptor message
Field Type Default value Description
segmentation_event_id integer 1 This is written to segmentation_descriptor.segmentation_event_id.
segmentation_upid_type integer 14 (0x0E) This is written to segmentation_descriptor.segmentation_upid_type. The value must be between 0 and 256, inclusive.
segmentation_upid string "" (empty string) This is written to segmentation_descriptor.segmentation_upid. The value must be a hexadecimal string, containing characters 0-9 and A-F.
segmentation_type_id integer 48 (0x30) This is written to segmentation_descriptor.segmentation_type_id. The value must be between 0 and 256, inclusive.
segment_num integer 0 This is written to segmentation_descriptor.segment_num. The value must be between 0 and 256, inclusive.
segments_expected integer 0 This is written to segmentation_descriptor.segments_expected. The value must be between 0 and 256, inclusive.
sub_segment_num integer null This is written to segmentation_descriptor.sub_segment_num. The value must be between 0 and 256, inclusive.
sub_segments_expected integer null This is written to segmentation_descriptor.sub_segments_expected. The value must be between 0 and 256, inclusive.

The following table shows the values that MediaTailor automatically sets for some of the segmentation_descriptor message's fields.

Values set by MediaTailor for a segmentation_descriptor message's fields
Field Type Value
segmentation_event_cancel_indicator Boolean True
program_segmentation_flag Boolean True
delivery_not_restricted_flag Boolean True

MediaTailor always sets the segmentation_duration_flag to True. MediaTailor populates the segmentation_duration field with the duration, in ticks, of the state content.

Note

When MediaTailor sends the time_signal messages, it sets the splice_command_type field in the splice_info_section message to 6 (0x06).

In HLS output, for an AdBreak with a time_signal message, the output EXT-X-DATERANGE tag includes a SCTE-35 field that is set to the serialized version of the splice_info_section message. For example, the following EXT-X-DATERANGE tag shows the serialized version of the splice_info_section message:

#EXT-X-DATERANGE:ID=\"1\",START-DATE=\"2020-09-25T02:13:20Z\",DURATION=300.0,SCTE35-OUT=0xFC002C00000000000000FFF00506800000000000160214435545490000000100E000019BFCC00E0030000000000000

In DASH output, for an AdBreak with a time_signal message, the output EventStream element includes a scte35:SpliceInfoSection element with scte35:TimeSignal and scte35:SegmentationDescriptor elements as its children. The scte35:TimeSignal element has a child scte35:SpliceTime element, and the scte35:SegmentationDescriptor element has a child scte35:SegmentationUpid element. For example, the following DASH output shows the EventStream element's child element structure:

<EventStream schemeIdUri="urn:scte:scte35:2013:xml" timescale="90000">
    <Event duration="27000000">
        <scte35:SpliceInfoSection protocolVersion="0" ptsAdjustment="0" tier="4095">
            <scte35:TimeSignal>
                <scte35:SpliceTime ptsTime="0" />
            </scte35:TimeSignal>
            <scte35:SegmentationDescriptor segmentNum="0" segmentationDuration="27000000" segmentationEventCancelIndicator="false" segmentationEventId="1" segmentationTypeId="48" segmentsExpected="0">
                <scte35:SegmentationUpid segmentationUpidFormat="hexBinary" segmentationUpidType="14">012345</scte35:SegmentationUpid>
            </scte35:SegmentationDescriptor>
        </scte35:SpliceInfoSection>
    </Event>
</EventStream>

You learned about using SCTE-35 messages to set up ad breaks in channel assembly, the structure and required fields for those messages, and sample HLS and DASH output that includes the SCTE-35 messages.