OBJECT-BASED UNEQUAL LOSS PROTECTION FOR MULTI-OBJECT VIDEO DELIVERY Nadjib Achir, Kave Salamatian, and Guy Pujolle LIP6 – Pierre et Marie Curie University 8, rue du Capitaine Scott, 75015 – Paris – France {nadjib.achir, kave.salamatian, guy.pujolle}@lip6.fr Abstract: The Multi Object video delivery results in a challenging new bit-allocation, rate-control, and losses protection problem. In this paper, we investigate the use of a FEC- based error control mechanism for error control in Multi-Object video system, as MPEG- 4. Our goal is to achieve object-based unequal error protection, thus assigning different level of protection to the video objects, in order to improve the perceptual video quality at the receiver. We use the dynamic programming approach to optimally select the level of protection to apply to each object. Our results demonstrate that, the video distortion at the receiver can be significantly reduced. Key words: Multi-Object Video Coding, MPEG-4, Loss Protection, FEC, Video Quality. 1 INTRODUCTION One of the greatest challenges of the past years has been the delivery of video streams over packet networks with the best effort service model. In such environment, multimedia terminals are confronted with fluctuating packet loss rates and delay jitter so that they must be able to protect the compressed video flow to guarantee the best possible quality reconstructed video at the decoder. Another consequence of the increasing role of video is an important evolution in the concept of audiovisual information. While for a very long time video processing dealt exclusively with fixed-rate sequences of rectangular-shaped images, interest is recently moving toward a more flexible concept. The subject of the encoding operations, in this case, is a set of visual elements/objects organized in both time and space in a flexible and arbitrary complex way. The ISO MPEG-4 [1] interna- tional standardization effort supports this new advanced concept of visual information for covering the generic coding of audiovisual information for a wide range of rates and applications. To provide the required video protection one can use error control techniques. Actually two different approaches can be used to deal with the transmission error in the networks. One is Automatic Repeat Request (ARQ) [2], and the other one is Forward Error Cor- rection (FEC). Most of common protocols are using ARQ to ask for retransmission of the lost data packets. However, in the case of distributing real-time multimedia data, the ARQ mechanism will result in considerable delay and jitter which are not suitable in such applications. On the other hand, Forward Error Correction (FEC) is a commonly used means of achieving video transmission with low error rates [3]. FEC techniques rely on transmitting the data in an encoded form, such that the redundancy introduced by the