Specifies how many seconds of content remain in the manifest after older segments are removed. At least one segment is always retained.
If neither residualPeriodInSeconds nor offsetInSeconds is set, all segments except the most recent are removed.
For DASH manifests that use SegmentTemplate, the retained duration also includes the value configured for liveEdgeOffset.

Specifies an offset, in seconds, from the start of the live event. All segments before this position are removed from the affected manifests.
For example, assume a segment length of 2 seconds and a configured timeshift of 120 seconds (2 minutes).
If the most recent segment is segment_80.ts, the manifest contains 60 segments, from segment_21.ts through segment_80.ts.
Setting offsetInSeconds to 120 sets the target segment number to 60 (targetSegmentNumber = offsetInSeconds / segmentLength). All segments before segment_60.ts are removed.
Each affected manifest then contains segment_60.ts through segment_80.ts.

Note: Do not set both offsetInSeconds and residualPeriodInSeconds.