J. Deregnaucourt · IEEE Transactions on Communication Technology · 1966
After a very brief resume of conventional pulse code modulation (PCM) features, this paper describes the operating principles of a variable length words - pulse code modulation system (VLWPCM). This new concept is a combination of TASI and conventional PCM. Time assignment speech interpolation or TASI is used on the very long routes, such as transoceanic cables, to improve the yield of the circuits at the cost of a very sophisticated terminal. The combination with PCM allows us to simplify the terminals in such a way that it can yield a lower cost. A coder and a decoder are described.
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Ngai-Man Cheung And, Ngai-man Cheung, Yuji Itoh · 2001
The variable length code (VLC) tables in the MPEG-1/2/4 and H.263 are fixed and optimized for a limited range of bit-rates, and they cannot handle a variety of applications. The universal variable length code (UVLC) is a new scheme to encode syntax elements and has some configurable capabilities. It is also being considered in the ITU-T H.26L. However, the configurable feature of the UVLC has not been well explored. In this paper we propose configuring the UVLC with the additional code configuration (ACC). The ACC is used to adapt UVLC to different symbol distributions by adjusting the partitioning of the symbols into different categories, and the code size assignment to different categories. Experimental results show that the UVLC with ACC outperforms the current proposed scheme in H.26L and the VLC tables of existing standards, while drastically simplifying the encoding and decoding process, and is applicable to a variety of applications.
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2015
Abstract—This paper presents architecture for context adaptive variable length coding (CAVLC) used in the MPEG-4 AVC/H.264 video coding. The proposed design implements the fine-grained zero skipping at the 4x4 block level and the individual coefficient level. This design saves more than half of cycle count and 41 % of area cost when compared with the other designs. The total gate count of the design is 10.2K gates. The design is implemented on Xilinx Spartan 3E Xc3s500 fpga and the total power consumption is estimated to be 0.081W. Keywords- CAVLC, MPEG-4, AVC/A.264.
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Yuji Itoh, Ngai-Man Cheung · 2002
A new technique for entropy coding named universal VLC (i.e., UVLC) was developed and applied to the motion vector. It was shown that UVLC for motion vector coding provides good performance in terms of coding efficiency as well as error resiliency. In this paper UVLC for DCT coefficient coding is presented. The features of the scheme are: (1) adaptable by parametric representation, (2) support of very low bitrate mode and (3) extensible to error resilient mode with bi-directionally decodable code. This favors a flexible image and video coding that should handle a variety of picture types and applications. The simulation results show that the proposed scheme slightly outperforms several VLC tables of existing standards in terms of coding efficiency. It is also expected that the proposed scheme can simplify the implementation and processing of VLC decoder. It shall also be noted that UVLC is being considered as a candidate component technique for ITU-T H.26L, i.e., next generation video coding algorithm standard.
Cited by 25
Ngai‐Man Cheung, Yuji Itoh · 2002
The variable length code (VLC) tables in MPEG-1/2/4 and H.263 are fixed and optimized for a limited range of bit-rates, and they cannot handle a variety of applications. The universal variable length code (UVLC) is a new scheme to encode syntax elements and has some configurable capabilities. It is also being considered in ITU-T H.26L. However, the configurable feature of the UVLC has not been well explored. We propose configuring the UVLC with the additional code configuration (ACC). The ACC is used to adapt UVLC to different symbol distributions by adjusting the partitioning of the symbols into different categories, and the code size assignment to different categories. Experimental results show that the UVLC with ACC outperforms the current proposed scheme in H.26L and the VLC tables of existing standards, while drastically simplifying the encoding and decoding process, and is applicable to a variety of applications.
Cited by 7
Junya Honda, H. Yamamoto · 2009
LDPC codes initially studied for channel coding can be applied to source coding, and Miyake-Muramatsu showed theoretically that the rate-distortion function can be achieved asymptotically by using LDPC codes for any stationary memoryless finite source. In their scheme, a source sequence is first vector-quantized by using an LDPC matrix and then it is compressed losslessly by another LDPC matrix. So, their scheme is fixed length coding. Unfortunately, it is not shown that their scheme can attain a good performance practically. In this paper, we propose a new variable length coding scheme, which uses linear programming for vector-quantization and arithmetic coding with probability estimated by belief propagation for lossless coding. The proposed variable length lossy coding can attain the rate-distortion function asymptotically. Furthermore, it can practically attain a performance considerably better than the so-called time sharing bound of the rate-distortion function.
Cited by 2
Reza Hashemian · 2002
Given a maximum allowable codeword length for a source S, an algorithm is developed to produce a set of optimal variable-length binary codes for the symbols in S. It is shown that no matter what the maximum size of the codewords is the algorithm always generates a set of optimal variable-length codes. And if no limit for the maximum code-length is specified the variable-length code becomes ultimately Huffman code. A maximum allowable codeword length is often necessary for data compression and transmission used in different applications. The limit for the codeword size might be necessary and essential because of the data-word size, the data buffers or even the data transmission rate. The ability to optimally control the length of the codewords provides a definite advantage over either a fixed code-length or a full variable-length code. Depending on particular applications and constraints, in the former case, one is able to choose the growth of the codewords that best suits the application and resources.
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G. Melnikov, G.M. Schuster, Aggelos K. Katsaggelos · 2002
This paper describes efficient and optimal encoding and representation of object contours. Contours are approximated by connected second-order spline segments, each defined by three consecutive control points. The placement of the control points is done optimally in the rate-distortion (RD) sense and jointly with their entropy encoding. We utilize a differential scheme for the rate and an additive area-based metric for the distortion to formulate the problem as a Lagrangian minimization. We investigate the sensitivity of the resulting operational RD curve on the variable length codes used and propose an iterative procedure arriving at the entropy representation of the original boundary for any given rate-distortion tradeoff.
Cited by 16
Sujata Bhavikatti, R. M. Banakar · Lecture notes in networks and systems · 2020
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Ismaeel, Tarik Zeyad · 2018
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Dipankar Das, R. Kumar, P. P. Chakrabarti · 2005
Most of the work done in the field of machine code compression is for fixed length instruction encodings. In this work we apply code compression on variable length instruction set processors whose encodings are already optimized to a certain extent with respect to their usages. We develop a dictionary based algorithm which utilizes unused encoding space of an instruction set architecture to encode code-words, and addresses issues arising out of variable length instructions. We test the algorithm with a RISC processor and include results for compression and performance in terms of cycle-counts and memory accesses respectively. We also present an efficient scheme for searching relocated branch addresses and analyze its performance.
Cited by 23
Subrat Kumar Dash, D. Krishna Sandeep Reddy, Arun K. Pujari · Statistical science and interdisciplinary research · 2008
Most of the commercial antivirus software fail to detect unknown and new malicious code. In order to handle this problem generic virus detection is a viable option. Generic virus detector needs features that are common to viruses. Recently Kolter et al. [16] propose an efficient generic virus detector using n-grams as features. The fixed length n-grams used there suffer from the drawback that they cannot capture meaningful sequences of different lengths. In this paper we propose a new method of variable-length n-grams extraction based on the concept of episodes and demonstrate that they outperform fixed length n-grams in malicious code detection. The proposed algorithm requires only two scans over the whole data set whereas most of the classical algorithms require scans proportional to the maximum length of n-grams.
Cited by 1
I Gusti Ayu Garnita Darma Putri, Nyoman Putra Sastra, I Made Oka Widyantara et al. · Majalah Ilmiah Teknologi Elektro · 2021
Paper ini merancang sebuah skema kompresi citra medis menggunakan DWT dengan mother wavelet Coiflet dan Symlet. Proses thresholding dan kuantisasi menjadi kunci terjadinya lossy compression di skema ini, dan data outputnya akan dikodekan dengan pengkodean Huffman atau Arithmetic. Terdapat empat kombinasi codec berbeda yakni: Coiflet-Huffman, Coiflet-Arithmetic, Symlet-Huffman yang masing-masing akan dianalisa kinerja kompresinya berdasarkan PSNR dan rasio kompresi. Pengujian kompresi menggunakan 3 citra medis grayscale berdimensi 160x160 piksel. Hasil pengujian menunjukan codec yang mampu menghasilkan PSNR dan rate paling optimal adalah codec Symlet-Arithmetic dengan nilai threshold yang dianjurkan yakni kurang dari 12. Pemberian nilai threshold diatas 12 akan menyebabkan PSNR citra rekonstruksi berada dibawah standar nilai minimum PSNR citra digital sebesar 30 dB.
Cited by 3Open access
Hui Zhou, Wenhui Cui, Fei Shao et al. · 2006
Joint source-channel coding and decoding is the hotspot in the field of coding recently. Realize joint source-channel coding (JSCC) with variable-length code, which can improve the transmission efficiency greatly. The paper adopts a kind of novel coding method, and constructs the cost-evaluating symmetrical reversible variable-length code that is fit for realizing joint source-channel coding and decoding. Finally the excellent simulation results have been obtained depending on the BSC and AWGN channels
Cited by 0
C. V. Ramamoorthy · Communications of the ACM · 1965
article Free AccessCode structures for protection and manipulation of variable-length items Author: C. V. Ramamoorthy Honeywell, Inc., Needham, MA Honeywell, Inc., Needham, MAView Profile Authors Info & Claims Communications of the ACMVolume 8Issue 101 January 1965pp 35–38https://doi.org/10.1145/363707.363716Published:01 January 1965Publication History 0citation201DownloadsMetricsTotal Citations0Total Downloads201Last 12 Months9Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF
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S. S. Gupta, D. Das, R. Kumar et al. · 2008
Most of the work done in the field of code compression pertains to processors with fixed length instruction encodings. In this work use code compression on variable length embedded RISC processors whose encodings are already optimized to a certain extent with respect to their usages. In this paper we present a dictionary based algorithm which addresses issues arising out-of variable lengths. We include results for compression and performance. 1.
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NTUR (臺灣機構典藏) · 2001
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NTUR (臺灣機構典藏) · 2001
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Chien-Wu Tsai, Ja‐Ling Wu · IEEE Transactions on Information Theory · 2001
Reversible variable length codes (RVLCs) have been adopted in emerging video coding standards-H.263+ and MPEG-4-to enhance their error-resilience capabilities (which are important and essential) in error-prone environments. This study proposes an efficient algorithm to construct a symmetrical RVLC from a given Huffman code. In addition, theoretical bounds on the maximum codeword length for fixed-length Huffman codes, and on the optimal average codeword lengths for sources with exponential distribution are provided.
Cited by 33
Krishna Kumar, Karen Thangam Jacob, B. Manjurathi · IOSR Journal of VLSI and Signal processing · 2014
One of the major challenges in testing a system-on-a-chip (SoC) is dealing with the large test data volume and large scan power consumption. To reduce the volume of test data, several test data compression techniques have been proposed. This paper presents a new test data compression scheme, which reduces test data volume for a system-on-a-chip (SoC). The proposed approach is based on the use of MT (Minimum Transition)-fill technique and Variable Prefix Run Length (VPRL) codes for test data compression. These VPRL codes can efficiently compress the data streams, that are composed of both runs of 0s and 1s. Experimental results for ISCAS'89 benchmark circuits supports and proves the proposed approach, better to the other existing techniques, by reducing test data volume.
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