Sequence number retrieval for voice data with redundancy

摘要

A sequence number is used to indicate where a payload of a voice data packet should fit in a data stream and a technique is described for retrieving the sequence number for redundant payloads. A receiver maintains a history of previously received timestamps and sequence numbers for previous payloads. A received packet is unpacked to obtain a primary payload and its associated sequence number and timestamp, and a redundant payload and its associated timestamp offset. The primary payload sequence number and timestamp are stored in the history. A time-span of the data stream covered by the packet is found using the timestamp offset, and a portion of the history selected based on the time-span. A timestamp parameter for the redundant payload is calculated using the primary payload timestamp and the timestamp offset, and is compared to timestamps in the selected portion of the history to derive the redundant payload sequence number. The history is updated to include the timestamp parameter and sequence number of the redundant payload.

主权项

1. A method for determining a sequence number indicating a position of a redundant payload of a voice data packet within a data stream, the method comprising:
unpacking a primary payload, a sequence number associated with the primary payload, a timestamp associated with the primary payload, a redundant payload, and a timestamp offset associated with the redundant payload from a voice data packet and storing the sequence number associated with the primary payload and the timestamp associated with the primary payload in a history of previously received timestamps associated with previous payloads, and previously received or derived sequence numbers associated with those previous payloads; calculating a timestamp parameter for the redundant payload based on the timestamp associated with the primary payload and the timestamp offset; calculating a time span of the data stream covered by the voice data packet using the timestamp offset; selecting a portion of the history based on the time span; comparing the timestamp parameter to one or more of the timestamps in the selected portion of the history to derive a sequence number for the redundant payload; and updating the history to include the timestamp parameter and derived sequence number of the redundant payload.