• Title/Summary/Keyword: Predictive Coding Scheme

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A Study of BWE-Prediction-Based Split-Band Coding Scheme (BWE 예측기반 대역분할 부호화기에 대한 연구)

  • Song, Geun-Bae;Kim, Austin
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.6
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    • pp.309-318
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    • 2008
  • In this paper, we discuss a method for efficiently coding the high-band signal in the split-band coding approach where an input signal is divided into two bands and then each band may be encoded separately. Generally, and especially through the research on the artificial bandwidth extension (BWE), it is well known that there is a correlation between the two bands to some degree. Therefore, some coding gain could be achieved by utilizing the correlation. In the BWE-prediction-based coding approach, using a simple linear BWE function may not yield optimal results because the correlation has a non-linear characteristic. In this paper, we investigate the new coding scheme more in details. A few representative BWE functions including linear and non-linear ones are investigated and compared to find a suitable one for the coding purpose. In addition, it is also discussed whether there are some additional gains in combining the BWE coder with the predictive vector quantizer which exploits the temporal correlation.

Context-based Predictive Coding Scheme for Lossless Image Compression (무손실 영상 압축을 위한 컨텍스트 기반 적응적 예측 부호화 방법)

  • Kim, Jongho;Yoo, Hoon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.1
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    • pp.183-189
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    • 2013
  • This paper proposes a novel lossless image compression scheme composed of direction-adaptive prediction and context-based entropy coding. In the prediction stage, we analyze the directional property with respect to the current coding pixel and select an appropriate prediction pixel. In order to further reduce the prediction error, we propose a prediction error compensation technique based on the context model defined by the activities and directional properties of neighboring pixels. The proposed scheme applies a context-based Golomb-Rice coding as the entropy coding since the coding efficiency can be improved by using the conditional entropy from the viewpoint of the information theory. Experimental results indicate that the proposed lossless image compression scheme outperforms the low complexity and high efficient JPEG-LS in terms of the coding efficiency by 1.3% on average for various test images, specifically for the images with a remarkable direction the proposed scheme shows better results.

Model Predictive Control System Design with Real Number Coding Genetic Algorithm (실수코딩 유전알고리즘을 이용한 모델 예측 제어 시스템 설계)

  • Bang, Hyun-Jin;Park, Jong-Chon;Hong, Jin-Man;Lee, Hong-Gi
    • Journal of the Korean Institute of Intelligent Systems
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    • v.16 no.5
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    • pp.562-567
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    • 2006
  • Model Predictive Control(MPC) system uses the current input which minimizes the difference between the desired output and the estimated output in the receding horizon scheme. In many cases (for example, system with constraints or nonlinear system), however, it is not easy to find the optimal solution to the above problem. In this paper, we show that real number coding genetic algorithm can be used to solve the optimal problem for MPC effectively. Also, we show by simulation that the real coding algorithm is mote natural and advantageous than the digital coding one.

Time-Domain Quantization and Interpolation of Pitch Cycle Waveform

  • Kim, Moo-Young
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.1E
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    • pp.11-16
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    • 2008
  • In this paper, a pitch cycle waveform (PCW) is extracted, quantized, and interpolated in a time domain to synthesize high-quality speech at low bit rates. The pre-alignment technique is proposed for the accurate and efficient PCW extraction, which predicts the current PCW position from the previous PCW position assuming that pitch periods evolve slowly. Since the pitch periods are different frame by frame, the original PCW is converted into the fixed-dimension PCW using the dimension-conversion method, and subsequently quantized by code-excited linear predictive (CELP) coding. The excitation signal for the linear predictive coding (LPC) synthesis filter is generated using the time-domain interpolation and interlink of the quantized PCW's. The coder operates at 4.2 kbit/s and 3.2 kbit/s depending on the pitch period. Informal listening test demonstrates the effectiveness of the proposed coding scheme.

An Image Coding Technique Using the Image Segmentation (영상 영역화를 이용한 영상 부호화 기법)

  • 정철호;이상욱;박래홍
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.24 no.5
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    • pp.914-922
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    • 1987
  • An image coding technique based on a segmentation, which utilizes a simplified description of regions composing an image, is investigated in this paper. The proposed coding technique consists of 3 stages: segmentation, contour coding. In this paper, emphasis was given to texture coding in order to improve a quality of an image. Split-and-merge method was employed for a segmentation. In the texture coding, a linear predictive coding(LPC), along with approximation technique based on a two-dimensional polynomial function was used to encode texture components. Depending on a size of region and a mean square error between an original and a reconstructed image, appropriate texture coding techniques were determined. A computer simulation on natural images indicates that an acceptable image quality at a compression ratio as high as 15-25 could be obtained. In comparison with a discrete cosine transform coding technique, which is the most typical coding technique in the first-generation coding, the proposed scheme leads to a better quality at compression ratio higher than 15-20.

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Improvement of the Linear Predictive Coding with Windowed Autocorrelation (윈도우가 적용된 자기상관에 의한 선형예측부호의 개선)

  • Lee, Chang-Young;Lee, Chai-Bong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.6 no.2
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    • pp.186-192
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    • 2011
  • In this paper, we propose a new procedure for improvement of the linear predictive coding. To reduce the error power incurred by the coding, we interchanged the order of the two procedures of windowing on the signal and linear prediction. This scheme corresponds to LPC extraction with windowed autocorrelation. The proposed method requires more calculational time because it necessitates matrix inversion on more parameters than the conventional technique where an efficient Levinson-Durbin recursive procedure is applicable with smaller parameters. Experimental test over various speech phonemes showed, however, that our procedure yields about 5 % less power distortion compared to the conventional technique. Consequently, the proposed method in this paper is thought to be preferable to the conventional technique as far as the fidelity is concerned. In a separate study of speaker-dependent speech recognition test for 50 isolated words pronounced by 40 people, our approach yielded better performance too.

Predictive Coding Methods in DCT Domain for Image Data Compression (영상 압축 부호화를 위한 DCT영역에서의 예측 부호화 방법)

  • Lee, Sang-Hee;Kim, Jae-Kyoon
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.8
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    • pp.86-95
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    • 1998
  • Intra-frame video compression, which cannot make use of temporal predictions, requires much higher bit rates compared with inter-frame schemes. In order to reduce bit rates, intra-frame predictive coding methods in DCT domain have been studied especially within the framework of the MPEG-4 video coding standard currently being developed. In this paper, we propose novel intra-frame predictive coding methods in DCT domain with the marginal complexity increase over the conventional methods . The proposed methods consist of a DC coefficient prediction method and two AC coefficient prediction methods. The proposed methods consist of a DC coefficient prediction method and two AC coefficient prediction methods. The proposed DC coefficient prediction method makes it possible to adaptively select the prediction directions without overhead bits, by comparing gradients of DC coefficients from neighboring blocks. As the AC coefficient prediction methods, first, we present an effective method which can improve the prediction directions of the MPEG-4 scheme by considering the DC coefficient of the current block to be coded. And, we present another effective method that decision on the prediction is carried out for each AC coefficient. Simulation results show that substantial bit savings can be achieved by the proposed methods.

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Adaptive Interleaved Motion Vector Coding using Motion Characteristics (움직임 특성을 이용한 적응적 교차 움직임 벡터 부-복호화)

  • Won, Kwang-Hyun;Yang, Jung-Youp;Park, Dae-Yun;Jeon, Byeung-Woo
    • Journal of Broadcast Engineering
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    • v.16 no.2
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    • pp.372-383
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    • 2011
  • This paper proposes an improved design of an interleaved motion vector coding scheme with flexibility in predictive motion vector component by exploiting motion characteristics. It can use component-wise adaptive motion vector predictor based on the utility of spatial and temporal motion field without any signaling bit for indicating decoder of the selected predictive motion vector component. Experiment with test video data shows about 1.99% (max 8.71%) bit rate reduction compared to the conventional H.264/AVC method.

Context-Based Minimum MSE Prediction and Entropy Coding for Lossless Image Coding

  • Musik-Kwon;Kim, Hyo-Joon;Kim, Jeong-Kwon;Kim, Jong-Hyo;Lee, Choong-Woong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 1999.06a
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    • pp.83-88
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    • 1999
  • In this paper, a novel gray-scale lossless image coder combining context-based minimum mean squared error (MMSE) prediction and entropy coding is proposed. To obtain context of prediction, this paper first defines directional difference according to sharpness of edge and gradients of localities of image data. Classification of 4 directional differences forms“geometry context”model which characterizes two-dimensional general image behaviors such as directional edge region, smooth region or texture. Based on this context model, adaptive DPCM prediction coefficients are calculated in MMSE sense and the prediction is performed. The MMSE method on context-by-context basis is more in accord with minimum entropy condition, which is one of the major objectives of the predictive coding. In entropy coding stage, context modeling method also gives useful performance. To reduce the statistical redundancy of the residual image, many contexts are preset to take full advantage of conditional probability in entropy coding and merged into small number of context in efficient way for complexity reduction. The proposed lossless coding scheme slightly outperforms the CALIC, which is the state-of-the-art, in compression ratio.

Enhanced Spectral Envelope Coding Scheme Using Inter-frame Correlation for G.729.1 (G.729.1 코더에서 프레임 간의 상호상관 관계를 이용한 개선된 스펙트럼 포락 코딩 방법)

  • Cho, Keun-Seok;Sung, Jong-Mo;Hahn, Min-Soo;Kim, Young-Il;Jeong, Sang-Bae
    • Phonetics and Speech Sciences
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    • v.1 no.4
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    • pp.97-103
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    • 2009
  • This paper describes a new algorithm for encoding spectral envelope in the time domain alias cancellation (TDAC) part of G.729.1. The spectral envelope and modified discrete cosine transform (MDCT) coefficients of the weighted code-excited linear predictive (CELP) coding error in lower-band and the higher-band input signal are encoded in the TDAC part. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, to improve the quality of decoded signals, two bit allocation strategies using reduced bits from the proposed algorithm are proposed. The performance of the proposed algorithm is evaluated in terms of objective quality and bit reduction rates. Experimental results show that the proposed algorithm increases the quality of sounds significantly.

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