摘要 :
In modern visual communications, transmitted data may be discarded because of network congestion. With the constraint on transmission delay, the lost data cannot be retransmitted and therefore may cause a fatal degradation on the ...
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In modern visual communications, transmitted data may be discarded because of network congestion. With the constraint on transmission delay, the lost data cannot be retransmitted and therefore may cause a fatal degradation on the visual quality. In this paper, we discuss some topics of delivering MPEG video over networks for robust transmission. Not only are relevant techniques introduced, but we also present an empirical bandwidth allocation strategy. The essential motivation of the proposed strategy is to eliminate the bust of MPEG video streams and thereby retain the duality of visual service. The experimental results indicate that the proposed strategy can allocate an effective bandwidth for MPEG video streams. Moreover, the proposed strategy can still maintain the same level of network utilization that compares to the optimum solution, which is found based on an exhaustive search.
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摘要 :
An adaptive Motion-JPEG coding scheme is proposed for desktop videoconferencing. The H.261 and Motion-JPEG are two commonly used codecs for videoconferencing. But, they have their own drawbacks. The problem of the H.261 is that it...
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An adaptive Motion-JPEG coding scheme is proposed for desktop videoconferencing. The H.261 and Motion-JPEG are two commonly used codecs for videoconferencing. But, they have their own drawbacks. The problem of the H.261 is that it is computation intensive, and a special hardware is required as a result. The cost of an H.261 codec is so far too expensive to be accepted by desktop users. The Motion-JPEG is a low-cost choice for videoconferencing. But, its coding efficiency is not as good as the H.261 because temporal redundancy is not removed. In the proposed design, we try to take advantage of both H.261 and Motion-JPEG. The blocks are classified into two categories: the background and the motion. The motion blocks are coded in the same way as Motion-JPEG. The method of coding the background blocks is basically similar to the H.261 except that two techniques are employed such that its computation has the same order as that of the Motion-JPEG. The performance of the Motion-JPEG and adaptive Motion-JPEG was investigated by conducting several experiments. It is shown that the presented scheme improved the picture quality by about 2 dB for a bit rate of 1.15 Mbps.
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摘要 :
This paper presents a new buffer control strategy that regulates the coded bit stream generated by MPEG video codec so that it can be transmitted robustly. This buffer control strategy is regarded as regulating the compressed bit ...
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This paper presents a new buffer control strategy that regulates the coded bit stream generated by MPEG video codec so that it can be transmitted robustly. This buffer control strategy is regarded as regulating the compressed bit stream to transmit with (pseudo) constant bit rate (CBR) through a fixed rate channel. It dynamically adjusts the quantizer scale for each frame under the consideration of the steady level of coding quality, the allocated bandwidth of transmission, the level of buffer occupancy, as well as the scene change. In the simulations, this strategy is implemented on MPEG coding algorithm and produces constant rate bit stream no matter what bandwidth is allocated or when the scene change occurs. Besides, the objective quality [in peak signal-to-noise ratio (PSNR)] of the proposed strategy is 1.5 dB more than that of TM5 and is almost the same as the results coded without buffer control. In addition, it always holds the smooth property.
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摘要 :
In this correspondence, a mean residual vector quantizer (MRVQ) is superimposed on the motion estimator for improving the intraframe coding quality of MPEG. The proposed scheme performs an MRVQ before executing the discrete cosine...
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In this correspondence, a mean residual vector quantizer (MRVQ) is superimposed on the motion estimator for improving the intraframe coding quality of MPEG. The proposed scheme performs an MRVQ before executing the discrete cosine transformation (DCT) for the purpose of curing the DCT intrinsic trouble of blocking effect at low bit rate.
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