• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.3
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• pp.23-32
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• 2007

The H.264/AVC video coding standard uses rate distortion optimization (RDO) method to improve the compression performance in the intra prediction. The complexity and computational load are increased more than previous standard by using this method, even though this standard selects the best coding mode for the current macroblock. This paper proposes a fast intra mode decision algorithm for H.264/AVC encoder based on dominant edge direction (DED). To apply the idea, this algorithm uses the approximation of discrete cosine transform (DCT) coefficient. By detecting the DED, 3 modes instead of 9 modes are chosen for RDO calculation to decide the best mode in the $4{\times}4$ luma block. As for the $16{\times}16$ luma and $8{\times}8$ chroma block, instead of 4 modes, only 2 modes are searched. Experimental results show that the computation time of the proposed algorithm is decreased to about 72% of the full search method with negligible quality loss.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.922-928
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• 2009

In H.264 as the newest video standard, 9 modes are used in order to predict the signal values of a block composed with several pixels by intra prediction. From these process, H.264 can bring high compression ratio in the encoded signal but the use of total 9 modes can give the inefficiency of the increase of the complexity induced by the amount of operation processing or the number of searching which is applied to compare adjacent pixels. This paper proposes a simplification method of prediction mode for the intra-picture coding by considering subjective interest region. There are certain region being interested within a picture of the video sequence. This region requires better subjective picture quality than the other regions. The proposed method increases the simplification of prediction mode by providing just essential modes of total 9 modes for less interest regions compared with the interest region. It is possible to get the additional 11%$\sim$15% simplification of the prediction mode by the proposed method, compared with the conventional method which simplifies the prediction mode for all of the picture by using the prediction characteristics only.

• Journal of the Korea Computer Graphics Society
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• v.17 no.2
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• pp.17-26
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• 2011

This paper presents an interactive progressive image transmission method, which enables a remote user to interactively select and transmit preferred regions from an index image. Our enhanced quadtree decomposition using PSNR-based rules and new implicit quadtree coding provide better rate-distortion performance than previous quadtree coders as well as leading bit plane methods. An adaptive traversal of child nodes is introduced for better visual display of restored images. Depth-first traversal combined with breadth-first traversal of the quadtree to accomplish interactive transmission as presented, results in a method that provides competitive performance at a low level of computational complexity. Moreover, our decoding requires only simple arithmetic which is enabling our method to be used for real-time mobile applications.

• The Journal of the Acoustical Society of Korea
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• v.19 no.2
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• pp.101-105
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• 2000

A telegram has been used to transmit the emergency news or celebration message. So, it has been very important media in our life. Although the telegram processing is more and more convenient, on the other hand, the telegram service contains only text message. The voice telegram is that delivering user's voice with text message. So, the voice telegram can be delivered sender's emotions and feelings. However, since voice information contains lots of data, large memory size and high cost processor are needed to deliver itself. In this paper, we proposed a new speech waveform coding method that has low complexity and low cost implementation for the voice telegram system. First, we fixed one basic speech waveform per pitch period and measured the waveform similarity between basic and neighbor speech waveform. Second, if the similarity satisfied threshold values, we compress the neighbor speech waveform with pitch and magnitude value per pitch period and if not, we save speech waveform. When the compression is about 45%, we obtained about 4 point in MOS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.585-593
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• 2017

In this paper, we propose a deblocking filter hardware architecture for low-power HEVC (High-Efficiency Video Coding) in-loop for mobile systems. HEVC performs image compression on a block-by-block basis, resulting in blockage of the image due to quantization error. The deblocking filter is used to remove the blocking phenomenon in the image. Currently, UHD video service is supported in various mobile systems, but power consumption is high. The proposed low-power deblocking filter hardware structure minimizes the power consumption by blocking the clock to the internal module when the filter is not applied. It also has four parallel filter structures for high throughput at low operating frequencies and each filter is implemented in a four-stage pipeline. The proposed deblocking filter hardware structure is designed with Verilog HDL and synthesized using TSMC 65nm CMOS standard cell library, resulting in about 52.13K gates. In addition, real-time processing of 8K@84fps video is possible at 110MHz operating frequency, and operation power is 6.7mW.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.823-832
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• 2016

This paper presents a generation method of test streams for verifying conformance of an UHD broadcasting receiver including decoders for video and audio as well as parsers for PSIP and closed caption data. The proposed test streams for video/audio signals can evaluate conformance of HEVC, AC-3 and DTS-HD standards. Especially, test streams for HEVC video compression standard can be used for testing syntax compliance and error resilience for a HEVC decoder. Moreover, the proposed test streams for system/program and closed caption can be applied for verifying parsers for PSIP and CEA-708 standards.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.297-305
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• 2007

In the paper, a Motion JPEG2000 coder which has been set as the standard for image compression by the Digital Cinema Initiatives (DCI), an organization composed of major movie studios was implemented into a target FPGA. The DWT (Discrete Wavelet Transform) based on lifting and the Tier 1 of EBCOT (Embedded Block Coding with Optimized Truncation) which are major functional modules of the JPEG2000 were setup with dedicated hardware. The Tier 2 process was implemented in software. For digital cinema the tile-size was set to support $1024\times1024$ pixels. To ensure the real-time operations, three entropy encoders were used. When Verilog-HDL was used for hardware, resources of 32,470 LEs in Altera's Stratix EP1S80 were used, and the hardware worked stably at the frequency of 150Mhz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5C
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• pp.490-496
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• 2006

H.264 is the most recent video coding standard, containing improved error resilience tools than previous video compression schemes. This paper shows an analysis of the dependency of error concealment (EC) performance on the expected number of correctly received neighboring macroblock(MB)s for a lost MB, applying error concealment schemes to the raster scan mode that is used in the previous video coding standard and the flexible macroblock ordering (FMO) which is one of error-resilience tools in H.264. We also present simulation results and performance evaluation with various packet loss rates. Simulation results show that the FMO mode provides better EC performances of $1{\sim}9dB$ PSNR improvements compared to the raster scan mode because of larger expected number of correctly received neighboring MBs. The PSNR improvement by FMO mode becomes higher as the intra-frame period is larger and the packet loss rate is higher.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.405-414
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• 2014

High Efficiency Video Coding(HEVC) obtains high compression ratio by applying recursive quad-tree structured coding unit(CU). However, this recursive quad-tree structure brings very high computational complexity to HEVC encoder. In this paper, we present fast CU decision algorithm in recursive quad-tree structure. The proposed algorithm estimates initial CU size before CTU encoding and checks the proposed condition using Coded Block Flag(CBF) and Rate-distortion cost to achieve the fast encoding time saving. And, intra mode estimation is also possible to be skipped using the CBF values acquired during the inter PU mode estimations. Experiment results shows that the proposed algorithm saved about 49.91% and 37.97% of encoding time according to the weighting condition.

• The Journal of the Acoustical Society of Korea
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• v.14 no.5
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• pp.89-93
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• 1995

To reduce the redundancy within samples that resulted from uniform sampling method, nonuniform sampling or nonredundant-sample coding methods can be considered. However, it is well known that when conventional nonuniform sampling methods are applied directly to speech signal, the required amount of data is comparable to or mure than that by uniform sampling method like PCM. To overcome this problem, a new nonuniform sampling method is proposed, in which nonuniform sampling is applied to the low-pass filtered speech signal and higher band is compensated by 8 colored Gaussian random noise with various noise levels. By this method, speech signal waveform can be encoded by 1.8 times larger compression ratio than the conventional nonuniform sampling method.