Wyniki wyszukiwania - BazTech

1

Lightweight compression with encryption based on asymmetric numeral systems

Duda Jarosław, Niemiec Marcin

International Journal of Applied Mathematics and Computer Science

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2023

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Vol. 33, no. 1

45--55

EN

Data compression combined with effective encryption is a common requirement of data storage and transmission. Low cost of these operations is often a high priority in order to increase transmission speed and reduce power usage. This requirement is crucial for battery-powered devices with limited resources, such as autonomous remote sensors or implants. Well-known and popular encryption techniques are frequently too expensive. This problem is on the increase as machine-to-machine communication and the Internet of Things are becoming a reality. Therefore, there is growing demand for finding trade-offs between security, cost and performance in lightweight cryptography. This article discusses asymmetric numeral systems-an innovative approach to entropy coding which can be used for compression with encryption. It provides a compression ratio comparable with arithmetic coding at a similar speed as Huffman coding; hence, this coding is starting to replace them in new compressors. Additionally, by perturbing its coding tables, the asymmetric numeral system makes it possible to simultaneously encrypt the encoded message at nearly no additional cost. The article introduces this approach and analyzes its security level. The basic application is reducing the number of rounds of some cipher used on ANS-compressed data, or completely removing an additional encryption layer when reaching a satisfactory protection level.

2

Increased Compression Efficiency of AVC and HEVC CABAC by Precise Statistics Estimation

Karwowski D., Domański M.

International Journal of Electronics and Telecommunications

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2018

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Vol. 64, No. 3

277--284

EN

The paper presents Improved Adaptive Arithmetic Coding algorithm for application in future video compression technology. The proposed solution is based on the Context-based Adaptive Binary Arithmetic Coding (CABAC) technique and uses the authors mechanism of symbols probability estimation that exploits Context-Tree Weighting (CTW) technique. This paper proposes the version of the algorithm, that allows an arbitrary selection of depth D of context trees, when activating the algorithm in the framework of the AVC or HEVC video encoders. The algorithm has been tested in terms of coding efficiency of data and its computational complexity. Results showed, that depending on depth of context trees from 0.1% to 0.86% reduction of bitrate is achieved, when using the algorithm in the HEVC video encoder and 0.4% to 2.3% compression gain in the case of the AVC. The new solution increases complexity of entropy encoder itself, however, this does not cause an increase of the complexity of the whole video encoder.

3

Entropy Coder for Audio Signals

Ulacha G., Stasinski R.

International Journal of Electronics and Telecommunications

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2015

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Vol. 61, No. 2

219-224

EN

In the paper an effective entropy coder designed for coding of prediction errors of audio signals is presented. The coder is implemented inside a greater structure, which signal modeling part is a lossless coding backward adaptation algorithm consisting of cascaded Ordinary Least Squares (OLS), three Normalized Least Mean Square (NLMS), and prediction error bias correction sections. The technique performance is compared to that of four other lossless codecs, including MPEG-4 Audio Lossless (ALS) one, and it is shown that indeed, on the average the new method is the best. The entropy coder is an advanced context adaptive Golomb one followed by two context adaptive arithmetic coders.

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Koncepcja implementacji w układzie FPGA dekodowania VLC dla potrzeb sprzętowej dekompresji w standardzie cyfrowego wideo DV

Cichoń S.

Pomiary Automatyka Kontrola

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2010

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R. 56, nr 7

755-757

PL

Kodowanie VLC (ang. Variable Length Coding) jest odmianą kodowania entropijnego. W różnych odmianach występuje ono w wielu standardach kompresji wideo. W niniejszej publikacji opisany zostanie algorytm kodowania VLC stosowany w kompresji DV, oraz następujący po nim etap formowania skompresowanego segmentu wizji. Zaproponowana zostanie koncepcja implementacji dekodera VLC w układzie reprogramowalnym, realizująca wszystkie trzy etapy, z uwzględnieniem aspektów wykorzystania w sprzętowym dekoderze.

EN

VLC coding (Variable Length Coding) is one of entropy type coding. With different modifications it is used in many video compression standards of both moving and still images, e.g. JPEG, MPEG-2, DV (IEC 61834). In the paper the VLC coding algorithm used in DV as well as a consecutive compressed video data forming phase together with the macroblock compressed area built in this process are described in details. This phase is performed in three stages, each on different data granularity, which generates some constraints with regard to FPGA implementation. In the paper there are presented experimental results which show that stages 2 and 3 have an influence on the higher overall quality of the decompression. The previous works [3][4] were focused on the first, or on the first and second decoding stage. There is described the concept design of VLC decoder implementation in a reprogrammable chip, realising all three stages in compliance with the IEC-61834 standard when taking into account reusing it in a hardware DV decoder as a processing element in the pipeline architecture.

5

Koncepcja implementacji trzyetapowego dekodowania VLC (w standardzie cyfrowego wideo DV) w układzie FPGA

Cichoń S.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2009

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T. 13, z. 3/1

797-805

PL

Kodowanie VLC (Yariable Length Coding) jest odmianą kodowania entropijnego. W różnych odmianach występuje ono w wielu standardach kompresji, zarówno obrazów ruchomych, jak i nieruchomych, m.in. JPEG, MPEG-2, DV (IEC 61834-2). W niniejszej publikacji opisany zostanie szczegółowo algorytm kodowania VLC stosowany w kompresji DV. Zaproponowana zostanie koncepcja implementacji dekodera VLC w układzie reprogramowalnym, realizująca wszystkie trzy etapy, z uwzględnieniem możliwości wykorzystania w sprzętowym dekoderze DV, jako element dekodowania potokowej architektury przetwarzania.

EN

VLC coding (Variable Length Coding) is one of entropy type of coding. With different modifications it is used in many of video compression standards, both moving, and still images, e.g. JPEG, MPEG-2, DV (IEC 61834). In this paper VLC coding algorithm used in DV will be described in details. Concept design of VLC decoder implementation, exercising all three stages in reprogrammable chip, will be presented, with consideration of reusing it in hardware DV decoder, as processing element in the pipeline architecture.