Fast mode decision for H.264 video coding in packet loss environment

In this paper, we propose a fast mode decision scheme for H.264 video coding to address the requirements of both low complexity and error resilience in realtime video communications. Traditional fast mode decision schemes are usually designed based on feature analysis on the source videos. However, the rate-distortion behaviors of the coding modes change when channel errors are involved. Therefore, the existing fast algorithms may not be applicable in error-resilient video coding. We first study the end-to-end rate-distortion behaviors of various coding modes, and then derive a hierarchical mode decision scheme. Different from the traditional fast algorithms that separate skip and inter modes at the beginning, we propose a fast estimation of the coding costs of skip and intra modes in a packet-loss environment, and then narrow the mode decision into one of the two paths: non-intra and non-skip. Testing shows the significant time savings of the proposed algorithm.