• Journal of the Institute of Convergence Signal Processing
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• v.4 no.2
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• pp.31-39
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• 2003

The MPEG-2 source coding algorithm is very sensitive to transmission errors due to using of variable-length coding. When the compressed data are transmitted, transmission errors are generated and error correction scheme is not able to be corrected well them. In the decoder error concealment (EC) techniques must be used to conceal errors and it is able to minimize degradation of video quality. The proposed algorithm is method to conceal successive macroblock errors of I-frame and utilize temporal information of B-frame and spatial information of P-frame In the previous GOP which is temporally the nearest location to I-frame. This method can improve motion distortion and blurring by temporal and spatial errors which cause at existing error concealment techniques. In network where the violent transmission errors occur, we can conceal more efficiently severe slice errors. This algorithm is Peformed in MPEG-2 video codec and Prove that we can conceal efficiently slice errors of I-frame compared with other approaches by simulations.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.55-64
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• 2016

Existing Android applications for streaming video in real time are dependent on the codec, which composes the encoding function, and the version of Android operating system. Also, for streaming video in real time, most applications should be connected with a separate desktop PC. To overcome these disadvantages, we propose a new application, which records and streams video in real time. Specifically, the proposed application uses the flash video file format, which is the common media file format supported by various versions of Android operating system. Through experiments, we show that it is possible for the proposed application to record the video screens more than 20 frames per second and to stream it in real time while using the existing video encoding methods.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.341-348
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• 2016

HEVC is the next compression standard and is expected to be used widely replacing the conventional H.264/AVC standard. The compression ratio of the HEVC is twice times than H.264/AVC, whereas its computational complexity is increased by up to 40%. Many research efforts have been made to reduce the computational complexity and to speed up encoding. For intra coding, the rough mode decision (RMD) is commonly applied. The rate-distortion optimization (RDO) process to decide the best mode is too complex so that RMD chooses the candidate modes with a simple process and sends the candidates to RDO process. However, for large-size blocks, the RMD also requires considerable computations. In this paper, a down-sampling scheme is proposed for the RMD process. The reference pixel loading, predicted pixel generation are performed using the down-sampled pixel data. When the proposed scheme is applied to the RMD, the computational complexity is reduced by 70% with a marginal bitrate increase of 0.04%. In terms of area of hardware-based RMD, the gate count and the buffer size is reduced 33% and 66%, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.1957-1964
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• 2010

In Video coding, the first frame is encoded in intra mode which generates a larger number of bits. In addition, the first frame is used for the inter mode encoding of the following frames. Thus the intial QP for the first frame of GOP affects the first frame as well as the following frames. Traditionally, the initial QP of a GOP is determined by the initial QP of the previous GOP and the average QP of the inter mode frames. In case of JM, the initial QP of a GOP is adjusted as the initial QP being less than the average QP of inter mode frames by two. However, this method is not suitable for the low bit rate video coding. In this paper, the linear relationship between the optimal QP and the ratio of the PSNR of the first frame and the average PSNR of the inter mode frames is first investigated and the linear model is proposed based on the results of the investigation. The proposed model calculate the optimal initial QP using the encoding results of the previous GOP. It is shown by experimental results that the new algorithm can predict the optimal initial QP more accurately and generate the PSNR performance better than that of the existing JM algorithm.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.6
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• pp.30-35
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• 2007

H.264/AVC provides better quality than other algorithms by using a deblocking filter to remove blocking distortion on block boundary of the decoded picture. However, this filtering process includes lots of memory accesses, which cause delay of overall decoding time. In this paper, we propose a data-reuse algorithm to speed up the process for the deblocking filter. To reuse the data, a new filtering order is suggested. By using this order, we reduce the memory access and accelerate the deblocking filter. The modeling of proposed algorithm is compiled under ARM ADS1.2 and simulated with Armulator. The results of the experiment compared with H.264/AVC standard are achieved on average 58.45% and 57.93% performance improvements at execution cycles and memory access cycles, respectively.

• Journal of IKEEE
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• v.17 no.4
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• pp.418-427
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• 2013

In this paper, we propose a parallel deblocking filter algorithm for H.264/AVC video standard. The deblocking filter has different filter processes according to boundary strength (BS) and each filter process requires various conditional calculations. The order of filtering makes it difficult to parallelize deblocking filter calculations. The proposed deblocking filter algorithm is performed on PRAGRAM which is a 1-D coarse grained reconfigurable architecture (CGRA). Each filter calculation is accelerated using uni-directional pipelined architecture of PRAGRAM. The filter selection and the conditional calculations are efficiently performed using dynamic reconfiguration and conditional reconfiguration. The parallel deblocking filter algorithm uses 225 cycles to process a macroblock and it can process a full HD image at 150 MHz.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.143-153
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• 2010

When providing high quality panoramic video across the Internet, mobile communications, and broadcasting areas, it requires a suitable video codec that satisfies both high-compression efficiency and random access functionality. The users must have high-compression efficiency in order to enable video streaming of high-volume panoramic data. Random access allows the user to move the viewpoint and direction freely. In this paper, we propose the parallel processing scheme under cell units in order to improve the performance of streaming service for large screen panoramic video in 10Mbps bandwidths based on H.264/AVC with high compression rate. This improved algorithm divides a screen composed of cells less than $256{\times}256$ in size, encodes it, and decodes it with the cells in the present view. At this point, encoding/decoding is parallel processed by the present cell units. Also, since the cells only included in the present view are packed and transmitted, the possible processing of not extricating blocks is proven by experiment.

• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.697-702
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• 2010

Contour artifact is known as the unintentional result of quantizing a flat area that has smooth gradients. In this letter, a decontouring algorithm is proposed to efficiently remove false contours that occur in typical block-based video coding applications. First, the algorithm goes through a refinement stage to determine candidate blocks probably having noticeable false contours with different kinds of features in a block. Then, pseudo-random noise masking is applied to those blocks to mitigate the contour artifacts. This block-based selective decontouring can efficiently remove the unnecessary processing of those blocks that have no false contour, which incidentally ensures a minor penalty in visual quality and computational complexity. The proposed algorithm was demonstrated, integrated into H.264/AVC, that visual quality can be significantly enhanced with an ignorable rate-distortion (RD) loss and an minor increase in computational complexity.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.293-304
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• 2011

In this paper, we proposed a new hardware architecture for motion estimation (ME) which is the most time-consuming unit among H.264 algorithms and designed to the type of intellectual property (IP). The proposed ME hardware consists of buffer, processing unit (PU) array, SAD (sum of absolute difference) selector, and motion vector (MVgenerator). PU array is composed of 16 PUs and each PU consists of 16 processing elements (PUs). The main characteristics of the proposed hardware are that current and reference frames are re-used to reduce the number of access to the external memory and that there is no clock loss during SAD operation. The implemented ME hardware occupies 3% hardware resources of StatixIII EP3SE80F1152C2 which is a FPGA of Altera Inc. and can operate at up to 446.43MHz. Therefore it can process up to 50 frames of 1080p in a second.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.29-37
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• 2008

To transmit video bit stream over low bandwidth such as wireless channel, high compression algorithm like H.264 codec is exploited. In transmitting high compressed video bit-stream over low bandwidth, packet loss causes severe degradation in image quality. In this paper, a new algorithm for recovery of missing or erroneous motion vector is proposed. Considering that the missing or erroneous motion vectors in blocks are closely correlated with those of neighboring blocks. Motion vector of neighboring blocks are clustered according to average linkage algorithm clustering and a representative value for each cluster is determined to obtain the candidate motion vector sets. As a result, simulation results show that the proposed method dramatically improves processing time compared to existing H.264/AVC. Also the proposed method is similar to existing H.264/AVC in terms of visual quality.