Which field of a Real-Time Transport Protocol packet allows receiving devices to detect lost packets?

The CSRC (Contributing Source ID) field identifies contributing sources for a stream that has been mixed by an RTP mixer, not for detecting lost packets.

The Timestamp field in an RTP packet reflects the sampling instant of the first octet in the RTP data packet and is used for synchronization and jitter buffer management, not directly for detecting lost packets.

The RTP header includes a 16-bit sequence number that increments by one for each RTP data packet sent. Receiving devices monitor this sequence number to detect packet loss, reordering, and duplication, which are critical for maintaining the quality of real-time media streams like voice and video.

The SSRC (Synchronization Source Identifier) identifies the synchronization source of an RTP stream, allowing different streams to be identified uniquely, but it does not track packet loss within a single stream.