alterantive mpd inserter

[cotid-qualabs]

This PR extends morpheus Nginx module to modify a requested MPD and insert alternative MPD replacement events at specific places, replacing SCTE 35 events. The upated code takes from SCTE-35 event the basic information like presentationTime and duration and depends of a static list to generate a map between spliceEventId and MPD Url (the alterantive content).

The new scte-to-alterantive fearture is integrated in both standalone morpheus and nginx-compiled workflows.

Tested with the following static MPD (stream_with_scte35_events.mpd):

<?xml version="1.0"?>
<MPD xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" mediaPresentationDuration="PT1M00s" suggestedPresentationDelay="15">
        <BaseURL>https://dash.akamaized.net/akamai/bbb_30fps/</BaseURL>
        <Period id="0" start="PT0.0S">
                <EventStream schemeIdUri="urn:scte:scte35:2013:xml" timescale="1000">
                        <Event presentationTime="5000" duration="9000" id="1">
                                <scte35:SpliceInfoSection xmlns:scte35="http://www.scte.org/schemas/35/2016">
                                        <scte35:SpliceInsert spliceEventId="1" outOfNetworkIndicator="true">
                                                <scte35:BreakDuration autoReturn="true" duration="9000" />
                                        </scte35:SpliceInsert>
                                </scte35:SpliceInfoSection>
                        </Event>
                </EventStream>
                <AdaptationSet mimeType="video/mp4" contentType="video" subsegmentAlignment="true" subsegmentStartsWithSAP="1" par="16:9">
                        <SegmentTemplate duration="120" timescale="30" media="$RepresentationID$/$RepresentationID$_$Number$.m4v" startNumber="1" initialization="$RepresentationID$/$RepresentationID$_0.m4v" />
                        <Representation id="bbb_30fps_1280x720_4000k" codecs="avc1.64001f" bandwidth="4952892" width="1280" height="720" frameRate="30" sar="1:1" />
                </AdaptationSet>
                <AdaptationSet mimeType="audio/mp4" contentType="audio" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
                        <Accessibility schemeIdUri="urn:tva:metadata:cs:AudioPurposeCS:2007" value="6" />
                        <Role schemeIdUri="urn:mpeg:dash:role:2011" value="main" />
                        <SegmentTemplate duration="192512" timescale="48000" media="$RepresentationID$/$RepresentationID$_$Number$.m4a" startNumber="1" initialization="$RepresentationID$/$RepresentationID$_0.m4a" />
                        <Representation id="bbb_a64k" codecs="mp4a.40.5" bandwidth="67071" audioSamplingRate="48000">
                                <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2" />
                        </Representation>
                </AdaptationSet>
        </Period>
        <UTCTiming schemeIdUri="urn:mpeg:dash:utc:direct:2014" value="2026-01-05T16:58:42.423" />
</MPD>

Testing with Standalone version

./morphdriver -n stream_with_scte35_events.mpd -a

Testing with Nginx-Compiled:

Send to Nginx:

curl -X PUT http://localhost:80/alterantive.mpd?mode=scte-to-alternative -H "Content-Type: application/dash+xml" --data-binary @/stream_with_scte35_events.mpd

Obtain modified mpd:

curl http://localhost:80/alterantive.mpd

<?xml version="1.0"?>
<MPD xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" mediaPresentationDuration="PT1M00s" suggestedPresentationDelay="15" suggestedPresentationDelay="15">
        <BaseURL>https://dash.akamaized.net/akamai/bbb_30fps/</BaseURL>
        <Period id="0" start="PT0.0S">
                <EventStream schemeIdUri="urn:mpeg:dash:event:alternativeMPD:replace:2025" timescale="1000" xmlns="">
                        <Event presentationTime="5000" duration="9000" id="1">
                                <ReplacePresentation url="https://dash.akamaized.net/dashif/ad-insertion-testcase1/batch2/real/b/ad-insertion-testcase1.mpd" earliestResolutionTimeOffset="5000" returnOffset="9000" maxDuration="9000" clip="false" startAtPlayhead="false" />
                        </Event>
                </EventStream>
                <AdaptationSet mimeType="video/mp4" contentType="video" subsegmentAlignment="true" subsegmentStartsWithSAP="1" par="16:9">
                        <SegmentTemplate duration="120" timescale="30" media="$RepresentationID$/$RepresentationID$_$Number$.m4v" startNumber="1" initialization="$RepresentationID$/$RepresentationID$_0.m4v" />
                        <Representation id="bbb_30fps_1280x720_4000k" codecs="avc1.64001f" bandwidth="4952892" width="1280" height="720" frameRate="30" sar="1:1" />
                </AdaptationSet>
                <AdaptationSet mimeType="audio/mp4" contentType="audio" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
                        <Accessibility schemeIdUri="urn:tva:metadata:cs:AudioPurposeCS:2007" value="6" />
                        <Role schemeIdUri="urn:mpeg:dash:role:2011" value="main" />
                        <SegmentTemplate duration="192512" timescale="48000" media="$RepresentationID$/$RepresentationID$_$Number$.m4a" startNumber="1" initialization="$RepresentationID$/$RepresentationID$_0.m4a" />
                        <Representation id="bbb_a64k" codecs="mp4a.40.5" bandwidth="67071" audioSamplingRate="48000">
                                <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2" />
                        </Representation>
                </AdaptationSet>
        </Period>
        <UTCTiming schemeIdUri="urn:mpeg:dash:utc:direct:2014" value="2026-01-08T13:49:30.815" />
</MPD>

Live Content Testing

The following script was used to generate a livestream simulator with stream_with_scte35_events.mpd:

#!/bin/bash
# live_simulator.sh
STATIC_MPD="stream_with_scte35_events_original.mpd"
COUNTER=0

while true; do
    COUNTER=$((COUNTER + 1))
    CURRENT_TIME=$(date -u +%Y-%m-%dT%H:%M:%SZ)
    
    cat "$STATIC_MPD" | \
    sed "s/type=\"static\"/type=\"dynamic\"/g" | \
    sed "s/mediaPresentationDuration=\"[^\"]*\"//g" | \
    sed "s|<MPD |<MPD availabilityStartTime=\"${CURRENT_TIME}\" publishTime=\"${CURRENT_TIME}\" |" | \
    sed 's|<UTCTiming [^>]*/>|<UTCTiming schemeIdUri="urn:mpeg:dash:utc:http-xsdate:2014" value="https://time.akamai.com/?iso"/>|g' | \
    curl -X PUT http://localhost:80/live.mpd?mode=scte-to-alternative \
      -H "Content-Type: application/dash+xml" \
      --data-binary @-
    
    echo "Update $COUNTER at $(date)"
    sleep 2
done

Execute:

./live_simulator.sh &

Then go to https://dashjs-samples.qualabs.com/SOW5AlternativeMPDDemos/live-to-live.html and replace "Main Live Stream URL" with http://localhost:80/live.mpd. Click Load Player.