Combined data partitioning and fine granularity scalability for channel adaptive video transmission

Layered video coding is used for adaptive transmission over channels having variable bandwidths. In the two well-known methods of data partitioning (DP) and fine granularity scalability (FGS), a base layer contains essential information and one or more enhancement layers contain fine detail. FGS is continuously scalable above the base layer by successive DCT coefficient bit planes of lower significance, but suffers losses in coding efficiency at low base layer rates. DP, on the other hand, only provides a base partition for header information and low-frequency coefficients and one or more enhancement partitions for higher-frequency coefficients. This results in degraded quality when the enhancement layer is lost but offers performance near single-layer video as the transmission rate approaches the encoding rate. DP is thus suited to bandwidths that vary over a narrow range, whereas FGS performs robustly over a wider range but not as well as single-layer or DP at bandwidths near the full rate. A combination of the two methods can provide higher quality than FGS alone, over a greater bandwidth range than DP alone. This is achieved by using DP on an FGS base layer, which can now have a sufficiently high rate to improve the FGS coding efficiency. Such a combination has been investigated for one form of DP, known as Rate-Distortion optimal Data Partitioning (RDDP), which attempts to provide the best possible base partition quality for a given rate. A method for combining FGS and DP is described, along with expected and computed performances for different rates.