Modified Steepest-Descent for Bit Allocation in Strongly Dependent Video Coding

The problem of efficient bit allocation for dependent video coding within the context of ascribing a quantizer to each macroblock (MB) within a frame is addressed in this letter. Strongly dependent MBs exhibit significant discontinuities on their operational distortion-rate (D-R) convex hulls that nullify the assumptions made for the use of the coordinate-wise steepest-descent (SD) algorithm. A qualified slope concept and a near-neighborhood look-ahead modification are introduced to circumvent these problems and are experimentally evaluated on a set of H.263+ encodings.