Modeling of layered video for low-bit-rate video conferencing applications

Heterogeneous wireless networks present several challenges for real-time video applications. Traditional video codecs are not particularly robust and perform poorly when faced with packet losses from congestion and bit errors within the channel. Combination of deterministic traffic smoothing and layered video coding techniques improves error resilience. Smoothing over single frame intervals improves statistical multiplexing gains. To mitigate a portion of the delay introduced by smoothing, we propose a predictive smoother using the RLS algorithm that reduces the delay due to encoding. Layered video coding transmits video in scalable layers of increasing quality. We present a simple hybrid wavelet/DCT layered coder along with an associated optimized layered video traffic model. The traffic model employs a simplified multistate Markov chain representing a non-uniformly quantized pseudo-histogram of observed bit-rates for each layer. The model captures the effect of deterministic smoothing and aids in evaluating scheduling algorithms as well as providing a simple call acceptance scheme.