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Multiple description coding (MDC) is a source coding technique that exploits path diversity to solve packet losses over error-prone channels. In this paper, we propose an improved drift-free multi-state MDC method based on H.264/AVC coding scheme. At the encoder side, we compress original video into multiple independent H.264 streams with different coding parameters, which can help us to control correlations between the descriptions. At the decoder side, each description is considered as a noisy observation of the original video, and a linear minimum mean square error (LMMSE) based merge algorithm is proposed to combine the descriptions. Experimental results show that the proposed algorithm can achieve better coding efficiency and visual quality than temporary MDC present in [1]. The error resilience ability is also improved by the fact that each frame is coded twice with different parameters. ©2009 IEEE.

An efficient temporal search range prediction method is proposed to reduce the complexity of multiple reference frames motion estimation (MRFME) in video coding. Based on a linear model of motion-compensated residue, the behavior of residues under MRFME is investigated, and the gain of multiple reference frames is analyzed. The proposed method utilizes the current residue to estimate the gain of searching more reference frames, and predicts the temporal search range that maintains the coding performance with minimum complexity. Experimental results show that the proposed scheme can significantly reduce the complexity in motion estimation while the degradation of the coding performance is negligible.

Due to the storage limit, the original raw video may not exist after compressing it into multiple video bitstreams using different compression parameters. In this paper, we suggest a least square error (LSE) algorithm to jointly decode the multiple video bitstreams, aiming to achieve better quality of the reconstructed video. The experimental results by joint decoding of multiple H.263 streams show that the proposed algorithm can significantly enhance the decoded video quality.

Multiple description coding (MDC) is a source coding technique that exploits path diversity to combat packet losses over error-prone channels. In this thesis, we proposed a novel drift-free multi-state MDC method. At the encoder side, the original video is compressed into multiple independently decodable H.263 streams, each with its own coding structure and prediction process, such that if one stream is lost, the other stream can still be used to produce video with acceptable quality. At the decoder side, each description is considered as a noisy observation of the original video. A minimum mean-square error (MMSE) based joint reconstruction algorithm is proposed to combine the descriptions. The experimental results show that the proposed algorithm has high coding efficiency, yet with strong error resilience.

In this paper, we analyze the error recovery performance of variable length codes (VLCs) transmitted over binary symmetric channel (BSC). Simple expressions for the exact mean symbol error rate (MSER) and the exact variance of symbol error rate (VSER) for any crossover probability p, are presented. We also prove that the mean error propagation length (MEPL) derived for single bit inversion error case is a scaled value of MSER when p, tends to zero. Comparisons with simulations demonstrate the accuracy of the MSER and VSER expressions.

This letter addresses the security issues of the multimedia encryption schemes using multiple Huffman table (MHT). A known-plaintext attack is presented to show that the MHTs used for encryption should be carefully selected to avoid the weak keys problem. We then propose chosen-plaintext attacks on the basic MHT algorithm as well as the enhanced scheme with random bit insertion. In addition, we suggest two empirical criteria for Huffman table selection, based on which we can simplify the stream cipher integrated scheme, while ensuring a high level of security.

Multi-hypothesis motion compensated filter (MHMCF) utilizes a number of hypotheses (temporal predictions) to estimate the current pixel which is corrupted with noise. While showing remarkable denoising results, MHMCF is computationally intensive as full search is employed in the expectation of finding good temporal predictions in the presence of noise. In the frame of MHMCF, a fast denoising algorithm FMHMCF is proposed in this paper. With edge preserved low pass prefiltering and noise-robust fast multihypothesis search, FMHMCF could find reliable hypotheses while checking very few search locations, so that the denoising process can be dramatically accelerated. Experimental results show that FMHMCF can be 10 to 15 times faster than MIIMCF, while achieving the same or even better denoising performance. © 2007 IEEE.

Multiple Description Coding (MDC) can be used as an Error Resilience (ER) technique for video coding. In case of transmission errors, Error Concealment can be combined with MDC to reconstruct the lost frame, such that the propagated error to the following frames is reduced. In this paper, we propose a new temporal error concealment method named Three-loop Temporal Interpolation (TLTI). TLTI can be well combined with temporal sub-sampling ER methods, such as MDC and Alternative Motion-Compensated Prediction. In the simulation, we compare the performance of TLTI with Unidirectional Motion Compensated Temporal Interpolation (UMCTI). Both visual and quantitive results show that TLTI can achieve a better video quality than UMCTI.

This paper addresses the security issues of the multimedia encryption schemes based on multiple Huffman table (M-HT). A detailed analysis of known-plaintext attack is presented to show that the Huffman tables used for encryption should be carefully selected to avoid the weak keys problem. Further, we propose an efficient chosen-plaintext attack on the basic MHT method as well as the enhanced scheme inserting random bits. We also show that random rotation in partitioned bit stream cannot essentially improve the security.