requestLiveStartOffset
open override fun requestLiveStartOffset(targetDurations: Double?, fallbackTargetDuration: Double?): Boolean
Positions a live item before its first frame renders: as soon as the playlist gives the window, the start is moved targetDurations × the playlist's EXT-X-TARGETDURATION (or fallbackTargetDuration) behind the window end. ExoPlayer cannot change the item's live offset after prepare() without re-preparing, so this is a seek issued before any frame is shown, re-aimed on every timeline update until the first frame renders. Returns false once a frame of the current item has rendered.