共查询到20条相似文献,搜索用时 109 毫秒
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Transform coding, a simple yet efficient image coding technique, has been adopted by the Joint Photographic Experts Group (JPEG) as the basis for an emerging coding standard for compression of still images. However, for any given transform encoder, the conventional inverse transform decoder is suboptimal. Better performance can be obtained by a nonlinear interpolative decoder that performs table lookups to reconstruct the image blocks from the code indexes. Each received code index of an image block addresses a particular codebook to fetch a component vector. The image block can be reconstructed as the sum of the component vectors for that block. An iterative algorithm for designing a set of locally optimal codebooks is developed. Computer simulation results demonstrate that this improved decoding technique can be applied in the JPEG baseline system to decode enhanced quality pictures from the bit stream generated by the standard encoding scheme 相似文献
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本文主要介绍了AVS视频解码的关键技术及解码原理。针对AVS视频解码器开源代码RM52J_r1解码效率相对低下的问题,根据该开源代码设计了新的AVS解码器。实验结果表明,在保证解码质量的前提下,解码速度有了很大的提高,基本上能达到实时解码的要求。 相似文献
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A recently proposed class of distributed source coding based video coders enables low-complexity compression and robust transmission over unreliable channels. These architectures process the video signal either in the pixel or in the transform domain generating some side information that permits a correct decoding of the coded image from a set of possible correlated sources. The approach proposed in this paper processes the video sequence both in the pixel and in the transform domain exploiting the advantages of both schemes and generating a set of lossy syndromes. The resulting video coding scheme requires a lower computational complexity at the decoder with respect to their transform-domain counterparts (like DISCOVER or PRISM) and provides a high compression gain and an increased robustness against channel losses. 相似文献
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Skoglund M. Hedelin P. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1999,45(2):515-532
We present an estimator-based, or soft, vector quantizer decoder for communication over a noisy channel. The decoder is optimal according to the mean-square error criterion, and Hadamard-based in the sense that a Hadamard transform representation of the vector quantizer is utilized in the implementation of the decoder. An efficient algorithm for optimal decoding is derived. We furthermore investigate suboptimal versions of the decoder, providing good performance at lower complexity. The issue of joint encoder-decoder design is considered both for optimal and suboptimal decoding. Results regarding the channel distortion and the structure of a channel robust code are also provided. Through numerical simulations, soft decoding is demonstrated to outperform hard decoding in several aspects 相似文献
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LDPC码在深空通信中有很好的实用价值,同时LDPC码也被广泛应用于光纤通信、卫星数字视频和音频广播等领域。针对LDPC译码器提出一种新的设计思路,将流水线思想从译码算法本身扩展到译码器的整体设计中,设计出可以多帧并行且结构简单的译码器,最后从吞吐量和资源消耗两方面进行仿真验证。 相似文献
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We introduce a new method for decoding short and moderate-length linear block codes with dense paritycheck matrix representations of cyclic form. This approach is termed multiple-bases belief-propagation. The proposed iterative scheme makes use of the fact that a code has many structurally diverse parity-check matrices, capable of detecting different error patterns. We show that this inherent code property leads to decoding algorithms with significantly better performance when compared to standard belief-propagation decoding. Furthermore, we describe how to choose sets of parity-check matrices of cyclic form amenable for multiple-bases decoding, based on analytical studies performed for the binary erasure channel. For several cyclic and extended cyclic codes, the multiple-bases belief propagation decoding performance can be shown to closely follow that of the maximum-likelihood decoder. 相似文献
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In this paper, a concatenated coding scheme for error control in data communications is presented and analyzed. In this scheme, the inner code is used for both error correction and detection; however, the outer code is used only for error detection. A retransmission is requested if either the inner code decoder fails to make a successful decoding or the outer code decoder detects the presence of errors after the inner code decoding. Probability of undetected error (or decoding error) of the proposed scheme is derived. An efficient method for computing this probability is presented. Throughput efficiency of the proposed error control scheme incorporated with a selective-repeat ARQ retransmission strategy is also analyzed. Three specific examples are presented. One of the examples is proposed for error control in the NASA Telecommand System. 相似文献
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Nam Ling Nien-Tsu Wang 《Broadcasting, IEEE Transactions on》2002,48(4):353-360
We present a scheme for real-time digital HDTV video decoding suitable for DVB or ATSC set-top boxes. Our technique is based on a dual decoding datapath controlled in two fixed-scheduling combinations with an efficient memory interface scheme for anchor pictures. Unlike other decoding approaches such as the slice bar decoding method and the crossing-divided method, our scheme reduces memory access contention problem to achieve real-time HDTV decoding without a high cost in overall decoder buffers, architecture, and bus. Our simulation shows that with a relatively low rate 81 MHz clock, our decoder can decode MPEG-2 MP@HL HDTV in real-time, based on a video format of 1920 /spl times/ 1080 pixels/frame at 30 frames/s, at a bit rate of 18-22 Mbps. 相似文献
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Software Code Generation for the RVC-CAL Language 总被引:1,自引:0,他引:1
Matthieu Wipliez Ghislain Roquier Jean-François Nezan 《Journal of Signal Processing Systems》2011,63(2):203-213
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Generalized minimum distance (GMD) decoding of Reed–Solomon (RS) codes can correct more errors than conventional hard-decision decoding by running error-and-erasure decoding multiple times for different erasure patterns. The latency of the GMD decoding can be reduced by the Kötter’s one-pass decoding scheme. This scheme first carries out an error-only hard-decision decoding. Then all pairs of error-erasure locators and evaluators are derived iteratively in one run based on the result of the error-only decoding. In this paper, a more efficient interpolation-based one-pass GMD decoding scheme is studied. Applying the re-encoding and coordinate transformation, the result of erasure-only decoding can be directly derived. Then the locator and evaluator pairs for other erasure patterns are generated iteratively by applying interpolation. A simplified polynomial selection scheme is proposed to pass only one pair of locator and evaluator to successive decoding steps and a low-complexity parallel Chien search architecture is developed to implement this selection scheme. With the proposed polynomial selection architecture, the interpolation can run at the full speed to greatly increase the throughput. After efficient architectures and effective optimizations are employed, a generalized hardware complexity analysis is provided for the proposed interpolation-based decoder. For a (255, 239) RS code, the high-speed interpolation-based one-pass GMD decoder can achieve 53% higher throughput than the Kötter’s decoder with slightly more hardware requirement. In terms of speed-over-area ratio, our design is 51% more efficient. In addition, compared to other soft-decision decoders, the high-speed interpolation-based GMD decoder can achieve better performance-complexity tradeoff. 相似文献
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A versatile time-domain Reed-Solomon decoder 总被引:2,自引:0,他引:2
Shayan Y.R. Le-Ngoc T. Bhargava V.K. 《Selected Areas in Communications, IEEE Journal on》1990,8(8):1535-1542
A versatile Reed-Solomon (RS) decoder structure based on the time-domain decoding algorithm (transform decoding without transforms) is developed. The algorithm is restructured, and a method is given to decode any RS code generated by any generator polynomial. The main advantage of the decoder structure is its versatility, that is, it can be programmed to decode any Reed-Solomon code defined in Galois field (GF) 2m with a fixed symbol size m . This decoder can correct errors and erasures for any RS code, including shortened and singly extended codes. It is shown that the decoder has a very simple structure and can be used to design high-speed single-chip VLSI decoders. As an example, a gate-array-based programmable RS decoder is implemented on a single chip. This decoder chip can decode any RS code defined in GF (25) with any code word length and any number of information symbols. The decoder chip is fabricated using low-power 1.5-μ, two-layer-metal, HCMOS technology 相似文献
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In this paper, an investigation into the behavior of modern narrowband power‐line communication systems when concatenated with both a fountain code named Luby transform code and a combination of nonlinear preprocessing techniques called signal clipping with blanking is presented. The new systems can be used in applications such as the automatic meter reading component of smart grid technology. Testing is performed on a range of systems provided by the G3 standard and the results show that a bit error rate improvement can be achieved with the correct encoder/decoder settings. The recommended settings include an adaptive technique that uses Gaussian elimination for Luby transform code decoding and code rates that depend on the system specifications used. From there, it is shown that a further improvement is achieved when both the Luby transform code and adaptive signal clipping/blanking based on signal power are combined. It is found that these modifications present a complexity trade‐off, which is higher on the receiver side. This added complexity can be well‐tolerated in automatic meter‐reading systems because of the star topology and asymmetric nature of the network, which has a centralized agent acting as a receiver that collects data from various transmitter nodes. 相似文献
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We present a bandwidth-efficient channel coding scheme that has an overall structure similar to binary turbo codes, but employs trellis-coded modulation (TCM) codes (including multidimensional codes) as component codes. The combination of turbo codes with powerful bandwidth-efficient component codes leads to a straightforward encoder structure, and allows iterative decoding in analogy to the binary turbo decoder. However, certain special conditions may need to be met at the encoder, and the iterative decoder needs to be adapted to the decoding of the component TCM codes. The scheme has been investigated for 8-PSK, 16-QAM, and 64-QAM modulation schemes with varying overall bandwidth efficiencies. A simple code choice based on the minimal distance of the punctured component code has also been performed. The interset distances of the partitioning tree can be used to fix the number of coded and uncoded bits. We derive the symbol-by-symbol MAP component decoder operating in the log domain, and apply methods of reducing decoder complexity. Simulation results are presented and compare the scheme with traditional TCM as well as turbo codes with Gray mapping. The results show that the novel scheme is very powerful, yet of modest complexity since simple component codes are used 相似文献
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In this paper, an architecture for real-time digital HDTV video decoding is presented. Our architecture is based on a dual decoding datapath controlled in a fixed schedule with an efficient write-back scheme for anchor pictures. The decoding datapath is synchronized at the block (8 × 8 pixels) level. Unlike other decoding approaches such as the slice bar decoding method and the cross-divide method, our scheme reduces memory access contention problem to achieve real-time HDTV decoding without a high cost in overall decoder buffers, architecture, and bus. In comparison to data-flow approaches, our method eliminates the complexity associated with tagged data operations. Our anchor picture storage is organized to minimize page-breaks during memory accesses. Simulation shows that with a relatively low rate 81 MHz clock, our decoder can decode MPEG-2 MP@HL HDTV in real-time, based on an ATSC video format of 1,920 × 1,080 pixels/frame at 30 frames/s, at a bit rate of 18 to 20 Mbps. 相似文献