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1

Efficient H.264 Intra Frame CODEC with Best Prediction Matrix Mode Algorithm

Hamdy Sara, Zekry Abdelhalim, Mohamed Wael A.

International Journal of Electronics and Telecommunications

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2020

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Vol. 66, No. 3

571--582

EN

The continuous growth of smart communities and ever-increasing demand of sending or storing videos, have led to consumption of huge amount of data. The video compression techniques are solving this emerging challenge. However, H.264 standard can be considered most notable, and it has proven to meet problematic requirements. The authors present (BPMM) as a novel efficient Intra prediction scheme. We can say that the creation of our proposed technique was in a phased manner; it's emerged as a proposal and achieved impressive results in the performance parameters as compression ratios, bit rates, and PSNR. Then in the second stage, we solved the challenges of overcoming the obstacle of encoding bits overhead. In this research, we try to address the final phase of the (BPMM) codec and to introduce our approach in a global manner through realization of decoding mechanism. For evaluation of our scheme, we utilized VHDL as a platform. Final results have proven our success to pass bottleneck of this phase, since the decoded videos have the same PSNR that our encoder tells us, while preserving steady compression ratio treating the overhead. We aspire our BPMM algorithm will be adopted as reference design of H.264 in the ITU.

2

Resource allocation in MIMO systems specific to radio communication

Ghaderi Bahar, Parhizgar Naser

Archives of Electrical Engineering

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2019

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Vol. 68, nr 1

91--100

EN

The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modulation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.

3

Optymalizacja kompresji Huffmana pod kątem podziału na bloki

Rybak K., Jamro E., Wielgosz M., Wiatr K.

Pomiary Automatyka Kontrola

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2014

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R. 60, nr 7

519--521

PL

Prezentowane w pracy badania dotyczą bezstratnej kompresji danych opartej o metodę Huffmana i zgodnej ze standardem deflate stosowanym w plikach .zip / .gz. Zaproponowana jest optymalizacja kodera Huffmana polegająca na podziale na bloki, w których stosuje się różne książki kodowe. Wprowadzenie dodatkowego bloku z reguły poprawia stopień kompresji kosztem narzutu spowodowanego koniecznością przesłania dodatkowej książki kodowej. Dlatego w artykule zaproponowano nowy algorytm podziału na bloki.

EN

According to deflate [2] standard (used e.g. in .zip / .gz files), an input file can be divided into different blocks, which are compressed employing different Huffman [1] codewords. Usually the smaller the block size, the better the compression ratio. Nevertheless each block requires additional header (codewords) overhead. Consequently, introduction of a new block is a compromise between pure data compression ratio and headers size. This paper introduces a novel algorithm for block Huffman compression, which compares sub-block data statistics (histograms) based on current sub-block entropy E(x) (1) and entropy-based estimated average word bitlength Emod(x) for which codewords are obtained for the previous sub-block (2). When Emod(x) - E(x) > T (T - a threshold), then a new block is inserted. Otherwise, the current sub-block is merged into the previous block. The typical header size is 50 B, therefore theoretical threshold T for different sub-block sizes S is as in (3) and is given in Tab. 2. Nevertheless, the results presented in Tab. 1 indicate that optimal T should be slightly different - smaller for small sub-block size S and larger for big S. The deflate standard was selected due to its optimal compression size to compression speed ratio [3]. This standard was selected for hardware implementation in FPGA [4, 5, 6, 7].

4

Realizacja kompresji danych metodą Huffmana z ograniczeniem długości słów kodowych

Rybak K., Jamro E., Wiatr K.

Pomiary Automatyka Kontrola

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2012

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R. 58, nr 7

662-664

PL

Praca opisuje zmodyfikowany sposób budowania książki kodowej kodu Huffmana. Książka kodowa została zoptymalizowana pod kątem implementacji sprzętowej kodera i dekodera Huffmana w układach programowalnych FPGA. Opisano dynamiczną metodę kodowania - książka kodowa może się zmieniać w zależności od zmiennego formatu kompresowanych danych, ponadto musi być przesłana z kodera do dekodera. Sprzętowa implementacja kodeka Huffmana wymusza ograniczenie maksymalnej długości słowa, w przyjętym założeniu do 12 bitów, co pociąga za sobą konieczność modyfikacji algorytmu budowy drzewa Huffmana.

EN

This paper presents a modified algorithm for constructing Huffman codeword book. Huffman coder, decoder and histogram calculations are implemented in FPGA similarly like in [2, 3]. In order to reduce the hardware resources the maximum codeword is limited to 12 bit. It reduces insignificantly the compression ratio [2, 3]. The key problem solved in this paper is how to reduce the maximum codeword length while constructing the Huffman tree [1]. A standard solution is to use a prefix coding, like in the JPEG standard. In this paper alternative solutions are presented: modification of the histogram or modification of the Huffman tree. Modification of the histogram is based on incrementing (disrupting) the histogram values for an input codeword for which the codeword length is greater than 12 bit and then constructing the Huffman tree from the very beginning. Unfortunately, this algorithm is not deterministic, i.e. it is not known how much the histogram should be disrupted in order to obtain the maximum codeword length limited by 12 bit. Therefore several iterations might be required. Another solution is to modify the Huffman tree (see Fig. 2). This algorithm is more complicated (when designing), but its execution time is more deterministic. Implementation results (see Tab. 1) show that modifi-cation of the Huffman tree results in a slightly better compression ratio.

5

Improved vector quantization scheme for grayscale image compression

Hu Y. C., Chen W. L., Lo C. C., Chuang J. C.

Opto-Electronics Review

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2012

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Vol. 20, No. 2

187-193

EN

This paper proposes an improved image coding scheme based on vector quantization. It is well known that the image quality of a VQ-compressed image is poor when a small-sized codebook is used. In order to solve this problem, the mean value of the image block is taken as an alternative block encoding rule to improve the image quality in the proposed scheme. To cut down the storage cost of compressed codes, a two-stage lossless coding approach including the linear prediction technique and the Huffman coding technique is employed in the proposed scheme. The results show that the proposed scheme achieves better image qualities than vector quantization while keeping low bit rates.

6

Quantization Step Parity-based Steganography for MP3 Audio

Diqun Y., Rangding W., Liguang Z.

Fundamenta Informaticae

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2009

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Vol. 97, nr 1/2

1-14

EN

Petitcolas has proposed a steganographic technique called MP3Stego which can hide secret messages in a MP3 audio. This technique is well-known because of its high capacity. However, in rare cases, the normal audio encoding process will be terminated due to the endless loop problem caused by embedding operation. In addition, the statistical undetectability of MP3Stego can be further improved. Inspired by MP3Stego, a new steganographic method for MP3 audio is proposed in this paper. The parity bit of quantization step rather than the parity bit of block size in MP3Stego is employed to embed secret messages. Compared with MP3Stego, the proposed method can avoid the endless loop problem and achieve better imperceptibility and higher security.