Layered (LC) and multiple description coding (MDC) have been proposed as source coding techniques that are robust to channel errors for video transmission. LC and MDC have similar characteristics: they both generate m...
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Layered (LC) and multiple description coding (MDC) have been proposed as source coding techniques that are robust to channel errors for video transmission. LC and MDC have similar characteristics: they both generate multiple sub-bitstreams, and it is permissible to drop some portion of the data from the sub-bitstreams during transmission for both methods. However, they are different in the sense that the sub-bitstreams for LC have different levels of importance while all sub-bitstreams for MDC are equally important. Since these two encoding techniques have similar properties, some performance comparisons between LC and MDC have recently been reported. However, these studies are still not conclusive because several scenarios have not been carefully considered. Furthermore, they have been performed in different environments. In this paper, we further investigate the error-resilience capabilities of these two encoding techniques through extensive experimentation. Although some of our conclusions agree with those in the literature, we believe that this paper provides the most comprehensive performance comparison yet between LC and MDC. (C) 2003 Elsevier Science B.V. All rights reserved.
In this work, we consider the application of unitary filter-banks for multiple description coding of independent, identically distributed Gaussian vector sources, We derive the redundancy-rate-distortion bound for thi...
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In this work, we consider the application of unitary filter-banks for multiple description coding of independent, identically distributed Gaussian vector sources, We derive the redundancy-rate-distortion bound for this class of signals. It is shown that for two-dimensional (2-D) Gaussian vector sources (resulting in a two-description system), 2 x 2 block transforms give all the achievable optimal points in the redundancy-rate-distortion function among the class of all unitary filter banks. similar results can be obtained for higher-dimensional transforms.
We study the problem of dividing the Z(2) lattice into partitions so that minimal intra-partition distance between the points is maximized. We show that this problem is analogous to the problem of sphere packing. An u...
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We study the problem of dividing the Z(2) lattice into partitions so that minimal intra-partition distance between the points is maximized. We show that this problem is analogous to the problem of sphere packing. An upper bound on the achievable intra-partition distances for a given number of partitions follows naturally from this observation, since the optimal sphere packing in two dimensions is achieved by the hexagonal lattice. Specific instances of this problem, when the number of partitions is 2, were treated in trellis-coded modulation (TCM) code design by Ungerboeck and others. It will be seen that methods previously used for set partitioning in TCM code design are asymptotically suboptimal as the number of partitions increases. We propose an algorithm for solving the Z(2) lattice partitioning problem for an arbitrary number of partitions.
We study the use of overcomplete (also known as oversampled) subband expansions for multiple description coding. The system proposed uses an overcomplete subband expansion (a subband expansion in which the number of s...
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ISBN:
(纸本)0819437646
We study the use of overcomplete (also known as oversampled) subband expansions for multiple description coding. The system proposed uses an overcomplete subband expansion (a subband expansion in which the number of subbands is larger than the downsampling factor of each subband) followed by independent coding (quantization and coding) of each of the subbands. The entire coding of each of the subbands is entirely contained within a single description. Using analysis in the polyphase domain, we study finding frequency responses of optimal filterbanks and the rate allocation across the subbands to minimize the end-to-end reconstruction error subject to a transmission rate constraint when a distribution over channel states is known. A general analysis of the problem is given and results are shown for a 3 x 2 expansion of a first-order autoregressive process.
multiple description coding is a forward error correction scheme where two or more descriptions of the source are sent to the receiver over different channels. If only one channel is received the signal can be reconst...
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ISBN:
(纸本)0819448222
multiple description coding is a forward error correction scheme where two or more descriptions of the source are sent to the receiver over different channels. If only one channel is received the signal can be reconstructed with distortion D-1 or D-2. On the other hand, if both channels are received the combined information is used to achieve a lower distortion Do. Our approach is based on the multiple State Video coding with the novelty that we achieve a flexible unbalance rate of the two streams by varying the quantization step size while keeping the original frame rate constant. The total bitrate R-T is fixed which is to be allocated between the two streams. If the assigned bitrates are not balanced there will be PSNR (peak signal to noise ratio) variations between neighbouring frames after reconstruction. Our goal is to find the optimal rate allocation while maximizing the average reconstructed frame PSNR and minin-dzing the PSNR variations given the total bitrate RT and the packet loss probabilities p(1) and p(2) over the two paths. The reconstruction algorithm is also taken into account in the optimization process. The paper will report results presenting optimal system designs for balanced (equal packet loss probabilities) but also for unbalanced path conditions (different packet loss probabilities).
作者：
Sagetong, POrtega, AUniv So Calif
Dept Elect Engn Syst Signal & Image Proc Inst Integrated Media Syst Ctr Los Angeles CA 90089 USA
multiple description coding (MDC) techniques have been explored in recent years as an alternative to other methods to provide robustness to multimedia information in the presence of losses. In a MDC approach some redu...
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ISBN:
(纸本)0819435929
multiple description coding (MDC) techniques have been explored in recent years as an alternative to other methods to provide robustness to multimedia information in the presence of losses. In a MDC approach some redundancy is preserved in the source coding so that, after appropriate packetization, if packet losses occur it is possible to recover by exploiting the redundancy (statistical or deterministic) between what was received and what was lost. While MDC techniques have shown some promising results, one potential drawback is the fact that changing their redundancy level may entail significant changes to the system. Since the level of redundancy should be adjusted to match the specific channel conditions, the difficulty in adapting can be a significant problem for time varying transmission scenarios. As an example, MDC techniques based on transform coding would require a modification of the transform at encoder and decoder each time the channel conditions change. In our previous work,we have proposed a simple approach for MDC that involves using a polyphase transform and deterministic redundancy (e.g., each sample of input data is transmitted several times, with different coding rates). This approach is useful in that it greatly simplifies the design of a MDC scheme, since the rate allocation determines the amount of redundancy Moreover, it provides a great deal of flexibility as it enables the choice of redundancy to be almost arbitrary. To demonstrate the effectiveness of our system we introduce an optimal bit allocation algorithm that allows us to select the amount of redundancy to be introduced in the signal that best matches a given target packet loss rate. Iris clear that such a trade-off exists, as the level of redundancy should increase when the packet loss rate increases, at the cost of some degradation in the corresponding error free performance. Our results show significant differences between optimal and suboptimal choices of redundancy. Moreover, gi
A new approach for multipledescription video coding is proposed. It employs a second-order predictor for motion-compensation, which predicts a current frame from two previously coded frames. The coder generates two d...
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A new approach for multipledescription video coding is proposed. It employs a second-order predictor for motion-compensation, which predicts a current frame from two previously coded frames. The coder generates two descriptions, containing the coded even and odd frames, respectively.. When only a single description (say, that containing even frames) is received, the decoder can only use previous even frames for prediction. The mismatch between the predicted frames at the encoder and decoder is explicitly coded to avoid error propagation in the ideal MD channels, where a description is either received intact or lost completely. By using the second-order predictor and coding the mismatch signal, one can also suppress error propagation in packet lossy networks where packets in either description can be lost. The predictor and the mismatch signal quantizer can be varied to achieve a Aide range of tradeoffs between coding efficiency and error resilience.
A layered compression algorithm is presented which delivers spatial scalable encoded bit streams for remote video monitoring system. The complexity of the algorithm is modest and is well suited to real time implementa...
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A layered compression algorithm is presented which delivers spatial scalable encoded bit streams for remote video monitoring system. The complexity of the algorithm is modest and is well suited to real time implementation. Based on the layered compression algorithm, a codec system model is established. High-speed video compression can be realized with parallel data compression in this codec system. For image reconstruction, a prediction method using two nearest pix points is presented.
In this paper the windowed Fourier encoding-decoding scheme applied to the multipledescription compression problem is analyzed, In the general case, four window functions are needed to define the encoder and decoder,...
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In this paper the windowed Fourier encoding-decoding scheme applied to the multipledescription compression problem is analyzed, In the general case, four window functions are needed to define the encoder and decoder, although this number can be reduced to three or two by using time-shift or frequency-shift division schemes. The encoding coefficients are next divided into two groups according to the eveness of either modulation or translation index. The distortion on each channel is analyzed using the Zak transform. For the optimal windows, explicit representation formulas are obtained and nonlocalization results are proved. Asymptotic formulas of the total distortion and transmission rate are established and the redundancy is shown to trade off between these two.
The framework of unequal loss protection (ULP) is an attractive method for the protection of the embedded image or video data source generated by a scalable coding scheme in the environment of packet switched networks...
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The framework of unequal loss protection (ULP) is an attractive method for the protection of the embedded image or video data source generated by a scalable coding scheme in the environment of packet switched networks. In this paper, an efficient preprocessing algorithm is presented based on the idea of the coarse scale cost-utility (CSCU) working curve. The experimental results show that the CSCU method significantly improves the efficiency of the ULP assignment framework with substantial memory and computation savings. We believe that the idea of coarse scale operation can also be successfully used in many other applications. (C) 2002 Elsevier Science B.V. All rights reserved.
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