Methods to Improve Coding Efficiency of SP Frames

SP-frame is a new picture type supported by H.264, and supports functions such as rate-switching and random-access. In this paper, we investigate several complementary methods to improve the coding efficiency of SP-frames. We show that by appropriately choosing reference pictures, the size of secondary SP frames can be reduced by up to 40% and 2% for random-access and rate-switching, respectively. We also demonstrate that a simple rule exists that allows the joint selection of the two quantization parameters associated with SP frames to minimize "requantization" error. Results shows 0.1 dB PSNR improvement over comparable choices.