Motion adaptive error resilient encoding for MPEG-4

Optimising delivery of video codecs such as MPEG-4 is vital to ensure that acceptable quality can be offered to 3G network customers. The error prone nature of mobile channels means that the video codec that is employed must be fairly robust. In the past, such research has required alteration to existing standards. Given the imminent implementation of 3G technologies, changing the standards is not a convenient option. This paper presents a technique for altering MPEG-4 encoding parameters to increase the error robustness of the output bitstream. It exploits the fact that frames with a high degree motion are often more sensitive to error than those with low amounts of motion. Using a simple model, the video packet length and number of adaptive intra refresh (AIR) blocks are varied according to the amount of motion in a frame. Simulations using a GPRS channel are presented to confirm the benefits of the proposed scheme