New Network and ATM Adaptation Layers for Interactive MPEG-2 Video Communications: A Performance Study Based on Psychophysics

In this paper, we present new Network and ATM Adaptation Layers for interactive MPEG-2 video communications. These layers provide reliable transmission by applying per-cell sequence numbering combined with a selective Forward Error Correction (FEC) mechanism based on Burst Erasure codes. We compare the performance of the proposed scheme with a transmission over AAL5 by simulating the transport of an MPEG-2 sequence over an ATM network. Performance is measured in terms of Cell Loss Ratio (CLR) and user perceived quality. The proposed layers achieve significant improvements on the cell loss figures obtained for AAL5 under the same traffic conditions. To evaluate the impact of cell losses at the user level, we apply a perceptual quality metric to the decoded MPEG-2 sequences. According to the computational metric and subjective rating, the proposed multimedia AAL (MAAL) achieves a graceful quality degradation. The application of a selective FEC achieves an even smoother image quality degradation with a low overhead