Error resilient two-layer H.263-based codecs for ATM environments

The introduction of new multi-media services and the enhancement of the existing services forced the existing networks to their performance limits. Most of the networks today face the problem of bandwidth limitation. ATM networks solve the problem of bandwidth bottleneck by the introduction of statistical multiplexing and priority switching. Many video coders/decoders (codecs) have been designed to suit this new technology [1-6]. Some of these codecs are designed to increase the resilience of the codec to cell loss as well as the sharing ability of the assigned bandwidth by implementing various layering techniques. Other multi-media services designers prefer to implement cell concealment techniques at the decoder side to combat cell loss [7]. This paper presents new two-layer error resilient video codecs based on the classical TWIN-H.261 and the Inter-Enhance H.261 video codecs [2-4]. A study of the performance of the proposed codecs is included in this paper with a comparison with the other classical two-layer codecs in terms of the reconstructed image quality, the resilience to cell loss, the bit rate produced and the codec complexity.