Cell-loss concealment in ATM video codecs

Methods for the interpolation of lost cells in asynchronous-transfer-mode (ATM) networks are studied. It is shown that use of motion-compensated previous frames gives the best results. The quality of the interpolated pictures improves if the motion vectors truly represent the actual motion in the scene. This is only possible with a two-layer coding scheme, where the motion vectors can be delivered to the decoder through the base-layer guaranteed channel. In derivation of the motion vectors at the encoder, use of uncoded input picture frames outperforms the conventional method of motion extraction from the previous coded pictures, despite the lower bit rate of the latter to the former. Depending on the quality of the base layer and the scene activity, the signal-to-noise ratio (SNR) in the cell-loss-interpolated areas can be improved by up to 10 dB