Duration of all segments (including evicted ones) up to the live sync point.
Whether the media source is currently a live stream.
Durations of the segments at the front of the window, oldest first - the ones eviction consumes. Real durations rather than targetDuration, which a manifest is free not to honour.
Live edge — end of the last fragment/part in the playlist.
Continuous (sliding window) or Event (start-over) live.
Earliest seekable position — start of the first fragment still in the playlist.
Safe live playback point (edge minus hold-back); the target for a "go to live" action.
Wall-clock time (ms since epoch) of the last manifest reload; for stale-manifest detection.
Media sequence number of the first segment in the window; identifies content across instances.
Target segment duration; useful as seek headroom above liveStartTime.
Runtime live state: the manifest-derived MediaLiveState plus the continuously-drifting
liveSyncPosition(a playback/latency concern, not persisted on the media state).