An Error Resilient Scheme for H.264 Video Coding Based on Data Hiding and Mode Decision

Abstract

Keyword -- H.264, error concealment, mode decision, data hiding

Although H.264 video coding standard provides several error resilience tools, the damage caused by the error propagation may still be tremendous. This thesis proposes two additional error resilience techniques that can improve the robustness of H.264 in noisy channels. Both of them are H.264 compatible, i.e., the bit streams can be decoded by a standard decoder with little or no degradation. The first technique is Nearest Neighbor motion compensated Error Concealment (NNEC) that utilizes a data hiding technique to embed the index of the neighboring block with the most similar motion vector into the bit stream, presumably the next slice. Once the decoder does not receive the correct MB data including its motion vector, it can use the nearest neighboring MB with the index extracted from the bit steam to perform much more accurate error concealment than the conventional blind motion concealment.

The second proposed technique is Distortion Estimated Mode Decision (DEMD). The mode decision in H.264, which is critical for the rate-distortion performance, does not consider the channel error in the computation. Therefore, an optimal mode selected by H.264 may not be optimal for a noisy environment. In the proposed DEMD, the encoder keeps estimating the decoder pixel distortion recursively for a given packet error rate. The overall pixel distortion of frame reconstruction at the decoding side includes the quantization error, the propagation error, and the concealment error. The estimates are integrated into a rate-distortion model for optimal switching between intra and inter coding for each MB.

By observing simulation results, the rate-distortion performances of the proposed algorithms are better than that of the conventional algorithms in all experimental cases. Specifically, the combination of NNEC/DEMD provides excellent performance.