stream.dash: opt publishTime/availabilityStartTime #6324
Merged
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Remove requirement from
publishTime
andavailabilityStartTime
in dynamic DASH manifests and simply default to UNIX Epoch.Resolves #6322
According to ISO/IEC 23009-1:2022 section 5.3.1.2,
MPD@publishTime
is an optional attribute with a default value, and it "shall be present" in dynamic manifests, same as theMPD@availabilityStartTime
attribute. For static manifests, we've already set these attributes to optional in the parser, as they are not important in this case.For dynamic manifests however, defaulting to UNIX Epoch can be problematic, depending on whether segment timelines include at least one timestamp anchor or not. If they don't, as the
SegmentTimeline.S@t
attribute is optional (section 5.3.9.6.2), then their anchor is the manifest's publishTime. Defaulting to 1970-01-01T00:00:00Z in dynamic manifests and using that as the anchor doesn't make sense, hence whyMPD@publishTime
was previously set as a required attribute.Parsers however should always be more lenient with data that's not 100% valid, so let's fix the attribute requirement.
The
MPD@availabilityStartTime
changes don't have any tests here, but that should be fine.