Forward error correction (FEC) improves the quality of compressed video transmitted through a lossy network for real-time applications such as video streaming. The FEC techniques are generally applied on source video packets at the frame level. In this paper, we propose a technique where the FEC is applied on source packets at the group-of-pictures (GoP) level assuming an MPEG-like compression scheme. We derive analytically an estimate of the average playable frame rate for a given packet loss probability. Our analysis over a range of network conditions indicates that in most practical network conditions, the proposed technique provides a larger playable frame rate compared to the frame-level FEC technique. This analysis results are also validated by video streaming simulations conducted on the NS-2 network simulator.
We propose two modi ed versions of the original wavelet di erence reduction (WDR) algorithm proposed by Tian and Wells. The rst algorithm encodes an image without entropy coding and achieves comparable PSNR performance with the original WDR at low bit rate while exceeding the PSNR performance of original WDR algorithm at medium to high bitrates. The second algorithm achieves slightly higher PSNR performance than that of original WDR with similar computational complexity. The modification to the original WDR is based on the observation that encoding the symbol streams generated in the sorting pass (significance map) and re nement pass (magnitudes) separately can be beneficial. We can either encode the symbol streams under different contexts using entropy coder, or output the raw symbol streams without entropy coding stage. It is shown in the experiments that up to 1/3 of both the encoding time and the decoding time can be saved without sacrificing any PSNR performance when compared to the original WDR.
A new block based motion estimation and compensation technique named overlapped multi-resolution motion compensation (OMRMC) is proposed. The algorithm employs the overlapped block motion compensation algorithm in wavelet domain to reduce the blocky artifacts in the predicted frames using the multi-resolution motion estimation (MRME) technique. Simulation results showed the use of OMRMC reduced up to 26% of the displaced frame difference energy compared with MRME.
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