Question: In a Transparent end-to-end Packet-switched Streaming Service (PSS), how is the `TotalRebufferingDuration` metric, reported by the PSS client, typically calculated for each resolution period of a stream?
Option 1: By averaging all individual rebuffering events' durations within the period.
Option 2: By summing up all occurred rebuffering durations over the period.
Option 3: By counting the number of rebuffering events and multiplying by a standard duration unit.
Option 4: By subtracting the total playback time from the total stream duration for each period.
Explanation: The correct calculation method for `TotalRebufferingDuration` involves summing up all the rebuffering durations that occurred during each resolution period of the stream. This approach accurately reflects the total time spent in rebuffering states, providing a clear metric for assessing streaming performance. This is crucial for telecom networks as it directly impacts the Quality of Experience (QoE) for end-users, helping operators to identify and optimize network bottlenecks or content delivery issues.