Receiver-oriented real-time error resilient video communication system: Adaptive recovery from error propagation in accordance with memory size at receiver

The NEWPRED method is a transmission error recovery technique for video com munication. In the NEWPRED method, both the transmitting side and the recei ving side store multiple reference pictures and select one of these to reco ver from an error. In general, the transmitting side has two methods of sel ecting a reference picture. One is ACK mode, in which the transmitting side makes its selection based on Ack signals sent from the receiving side, and the other is NACK mode, in which the selection is based on Nack signals se nt from the receiving side. To reduce picture-quality degradation caused by errors, the transmitting side switches between these two modes by evaluati ng transmission error condition. However, when the reference picture memory size is small, the receiving side cannot decode the bitstream because it d oes not have the picture data indicated by the transmitting side. To solve this problem, we propose a new method of switching, in which the receiving side controls mode switching according to the size of the reference picture memory. We demonstrate its effectiveness in computer simulations. (C) 2000 Scripta Technica.