Asynchronous transfer mode (ATM) networks are expected to be widely used as the B-ISDN in the future, and being discussed at CCITT SGXVIII for the standardization. CBR (Continuous Bit Rate) and VBR (Variable Bit Rate) services will be provided on ATM networks. A VBR service is thought to enable transmitted picture quality to be improved. However, cell loss, which may occur in a VBR service, causes catastrophic damages in reproduced image. We have already proposed a layered coding technique in a discrete cosine transform (DCT) coding scheme, in order to accomplish packet loss compensation. Recently, we have constructed the prototype CODEC involved in the layered coding technique. In this paper, we describe about the design of the CODEC and its performance. Especially, we describe the results of the subjective picture quality assessment when cell loss occurrs.
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