Preload content from multiple periods

[dsilhavy]

This issue was originally reported in #4867

Environment

• The MPD passes the DASH-IF Conformance Tool on https://conformance.dashif.org/
• The stream has correct Access-Control-Allow-Origin headers (CORS)
• There are no network errors such as 404s in the browser console when trying to play the stream
• The issue observed is not mentioned on https://github.com/Dash-Industry-Forum/dash.js/wiki/FAQ
• The issue occurs in the latest reference client on http://reference.dashif.org/dash.js/ and not just on my page

• Link to playable MPD file: 'https://dash.akamaized.net/dashif/ad-insertion-testcase1/batch2/real/b/ad-insertion-testcase1.mpd'
• Dash.js version: 5.1.0
• Browser name/version: Chrome 141.0.7390.54
• OS name/version: Windows 11

Steps to reproduce

1. Initialize dash.js player without attaching a video element and call preload() on a multi-period MPD with cacheInitSegments enabled
2. Only the content of the first period is preloaded even if it does not meet the buffer target

Code used to set up the player:

function init() {
    var video,
        player,
        url = 'https://dash.akamaized.net/dashif/ad-insertion-testcase1/batch2/real/b/ad-insertion-testcase1.mpd';
    
    video = document.getElementById('video');
    player = dashjs.MediaPlayer().create();
    player.initialize(null, url, false, NaN);
    player.updateSettings({
        streaming: {
            cacheInitSegments: true,
        }
    });
    player.preload();
    setTimeout(function () {
        player.attachView(video);
    }, 5000);
}

MPD:

<?xml version="1.0"?>
<!-- MPD file Generated with GPAC version 1.1.0-DEV-rev737-g7ee960336-master at 2021-04-19T14:18:41.035Z -->
<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" minBufferTime="PT1.920S" type="static" mediaPresentationDuration="PT0H0M28.800S" maxSegmentDuration="PT0H0M1.920S" profiles="urn:mpeg:dash:profile:full:2011,urn:mpeg:dash:profile:cmaf:2019">
 <ProgramInformation moreInformationURL="http://gpac.io">
  <Title>ad-insertion-testcase1.mpd generated by GPAC</Title>
 </ProgramInformation>

 <Period duration="PT0H0M9.600S">
  <AdaptationSet segmentAlignment="true" lang="eng" startWithSAP="1">
   <SegmentTemplate media="m1_audio_$Number$.m4s" initialization="m1_audio_init.mp4" timescale="48000" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="92160" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="1" mimeType="audio/mp4" codecs="mp4a.40.2" audioSamplingRate="48000" bandwidth="128000">
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
   </Representation>
  </AdaptationSet>
  <AdaptationSet segmentAlignment="true" maxWidth="960" maxHeight="426" maxFrameRate="25" par="480:213" lang="eng" startWithSAP="1">
   <SegmentTemplate media="m1_video_$Number$.m4s" initialization="m1_video_init.mp4" timescale="12800" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="24576" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="4" mimeType="video/mp4" codecs="avc1.64001E" width="960" height="426" frameRate="25" sar="1:1" bandwidth="100000">
   </Representation>
  </AdaptationSet>
 </Period>
 <Period start="PT0H0M9.600S" duration="PT0H0M9.600S">
  <AdaptationSet segmentAlignment="true" lang="und" startWithSAP="1">
   <SegmentTemplate media="m2_audio_$Number$.m4s" initialization="m2_audio_init.mp4" timescale="48000" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="92160" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="2" mimeType="audio/mp4" codecs="mp4a.40.2" audioSamplingRate="48000" bandwidth="128000">
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
    <BaseURL>https://dash.akamaized.net/dashif/ad-insertion-testcase1/batch2/real/b/</BaseURL>
   </Representation>
  </AdaptationSet>
  <AdaptationSet segmentAlignment="true" maxWidth="960" maxHeight="426" maxFrameRate="25" par="480:213" lang="und" startWithSAP="1">
   <SegmentTemplate media="m2_video_$Number$.m4s" initialization="m2_video_init.mp4" timescale="12800" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="24576" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="5" mimeType="video/mp4" codecs="avc1.64001E" width="960" height="426" frameRate="25" sar="1:1" bandwidth="100000">
    <BaseURL>https://dash.akamaized.net/dashif/ad-insertion-testcase1/batch2/real/b/</BaseURL>
   </Representation>
  </AdaptationSet>
 </Period>
 <Period start="PT0H0M19.200S" duration="PT0H0M9.600S">
  <AdaptationSet segmentAlignment="true" lang="eng" startWithSAP="1">
   <SegmentTemplate media="m3_audio_$Number$.m4s" initialization="m3_audio_init.mp4" timescale="48000" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="92160" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="3" mimeType="audio/mp4" codecs="mp4a.40.2" audioSamplingRate="48000" bandwidth="128000">
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>
   </Representation>
  </AdaptationSet>
  <AdaptationSet segmentAlignment="true" maxWidth="960" maxHeight="426" maxFrameRate="25" par="480:213" lang="eng" startWithSAP="1">
   <SegmentTemplate media="m3_video_$Number$.m4s" initialization="m3_video_init.mp4" timescale="12800" startNumber="1">
    <SegmentTimeline>
     <S t="0" d="24576" r="4"/>
    </SegmentTimeline>
   </SegmentTemplate>
   <Representation id="6" mimeType="video/mp4" codecs="avc1.64001E" width="960" height="426" frameRate="25" sar="1:1" bandwidth="100000">
   </Representation>
  </AdaptationSet>
 </Period>
</MPD>

Observed behavior

The preload method only downloads the segments for the first period

Expected behavior

The player supports preloading for multi-period assets.