Systems and methods for error resilience and random access in video communication systems

摘要

Systems and methods for error resilient transmission and for random access in video communication systems are provided. The video communication systems are based on single-layer, scalable video, or simulcast video coding with temporal scalability, which may be used in video communication systems. A set of video frames or pictures in a video signal transmission is designated for reliable or guaranteed delivery to receivers using secure or high reliability links, or by retransmission techniques. The reliably-delivered video frames are used as reference pictures for resynchronization of receivers with the transmitted video signal after error incidence and for random access.

主权项

1. A system for media communications between a transmitting endpoint and one or more receiving endpoint(s) over a communications network, the network having one or more layered media transport link(s) including a more reliable media transport link to or from each endpoint, the system comprising:
an encoder which encodes transmitted media as frames in a threaded coding structure having a number of different frame types, the frames including a sequence of reference frames; a decoder which decodes received media based on reference frames therein; and a particular select subset of the frames in the threaded coding structure that is designated as a type (“R”) for reliable transport to the one or more receiving endpoint(s) over the more reliable transport link, wherein the subset of the frames of the type R is particularly selected to include at least the frames of the lowest temporal layer in the threaded coding structure and such that the decoder can decode at least a portion of the received media based on a reliably received frame of the type R after packet loss or error and thereafter is synchronized with the encoder, wherein reliable transport of the reference frames of the type R comprises retransmissions over the more reliable transport link based on a protocol of Acknowledgment (ACK) and/or No Acknowledgment (NACK) messages, and wherein the particular select subset of the frames that is designated as a type R for reliable transport to the decoder over the more reliable transport link comprises intra and inter macroblocks, and wherein the encoder further comprises a reliability and random access (RRC) module that recalculates the allocation of intra macroblocks in coding future frames in response to packet loss in or a new endpoint joining a current communication session.