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300-815 · Question #27

Which description of RTP timestamps or sequence numbers is true?

The correct answer is D. The timestamp is used to place the incoming audio and video packets in the correct timing order (playout delay compensation).. In RTP (Real-time Transport Protocol), the timestamp field reflects the sampling instant of the first audio or video sample in the packet. The receiver uses timestamps to correctly schedule packet playback, compensating for network jitter by buffering packets and playing them out

Signaling and Media Protocols

Question

Which description of RTP timestamps or sequence numbers is true?

Options

  • AThe sequence number is used to detect losses.
  • BTimestamps increase by the time "carrying" by a packet.
  • CSequence numbers increase by four for each RTP packet transmitted.
  • DThe timestamp is used to place the incoming audio and video packets in the correct timing order (playout delay compensation).

How the community answered

(44 responses)
  • A
    2% (1)
  • B
    5% (2)
  • C
    7% (3)
  • D
    86% (38)

Explanation

In RTP (Real-time Transport Protocol), the timestamp field reflects the sampling instant of the first audio or video sample in the packet. The receiver uses timestamps to correctly schedule packet playback, compensating for network jitter by buffering packets and playing them out at the proper time-this is called playout delay compensation or jitter buffering. Option A is partially true (sequence numbers can help infer losses) but their primary role per RFC 3550 is reordering packets; loss detection is secondary. Option B is misleadingly worded. Option C is false-sequence numbers increment by exactly 1 per RTP packet, not by four.

Topics

#RTP#Timestamps#Sequence Numbers#Playout Delay

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