fix: Low Latency DASH: include the "availabilityTimeComplete=false" attribute

[CaitlinOCallaghan]

Low Latency DASH - availabilityTimeComplete=false

Low Latency DASH manifests generated by Packager were missing the attribute availabilityTimeComplete. As per the DASH specs:

the AdaptationSet@availabilityTimeCompleteshould be present and be set to 'FALSE'

The Issue

The missing attribute caused ULL streams from Shaka Packager to no longer be compatible with DASH.js. Previous versions of DASH.js allowed users to specify ULL mode when initializing the player. However, the most recent releases of DASH.js automatically detect ULL by scanning the manifest for ULL specific attributes. Although there are many attributes only associated with ULL, DASH.js only greps for availabilityTimeComplete in its detection logic. Because of the missing attribute in Packager and the limited ULL verification criteria by DASH.js, Packager streams were not being treated as low latency streams by DASH.js.

Testing

Unit Testing

./mpd_unittest --gtest_filter="SegmentTemplateTest.OneSegmentLowLatency"
./mpd_unittest --gtest_filter="LowLatencySegmentTest.LowLatencySegmentTemplate"

Manual Testing

• Created a low latency stream with Shaka Packager
• Observed the expected availabilityTimeComplete=false attribute in the generated DASH manifest.