• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.8
• /
• pp.104-113
• /
• 2014

The existing rough mode decision (RMD) algorithm, used in HEVC standard loses the coding efficiency and wastes encoding time when encoding using transform skip mode (TSM) because the RMD algorithm in HEVC uses a selection method that is designed for DCT, not for TSM. This paper proposes a new RMD algorithm for TSM in HEVC. Our proposed RMD algorithm enhances the coding efficiency by employing a new cost function to increase the probability of selecting the best intra prediction mode for TSM. In addition, it reduces the encoding time by skipping the encoding process of least feasible TSM based on a newly proposed threshold value. The experiment results show that the proposed method achieves coding gains of -0.3% for screen contents with a 10% reduction in encoding time compared to those of the HEVC standard.

• Journal of KIISE:Information Networking
• /
• v.30 no.6
• /
• pp.695-704
• /
• 2003

A wavelet-based video stream is more susceptible to the network transmission errors than DCT-based video. This is because bit-errors in a subband of a video frame affect not only the other subbands within the current frame but also the subsequent frames. In this paper, we propose a video source coding scheme called IPC(Intra Prediction Coding) scheme in order to reduce the error propagation to the subsequent frames. In the proposed scheme, a subband except LL subband in the current frame refers to the lower-level subband within the same frame. This reduces the error propagation to subsequent frames. We evaluated the performance of our proposed scheme in the simulated wireless network environment. As a result of tests, it was shown that the proposed algorithm shows better performance than MRME in a heavy motion image sequence while IPC outperforms MRME at a high bit-rate in small motion image sequence.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2009.01a
• /
• pp.618-622
• /
• 2009

An improvement of standard encoder has been saturated recently. However, new coding method does not have a compatibility with conventional standard. To solve this problem, new concept coding method that has a semicompatibility with standard may be discussed. On the other hand, cyclic Intra-picture coding is used for access and refreshment. However, I-picture spend large amount of bits. An enhancement of I-picture is desired with keeping its refreshment performance. Further, it's a problem that quality change at the border of GOP because of its independency. To respond these, we propose the coding which is applied an inter-frame processing at the border of GOP. Applied method is the reduction of quantization error using the motion compensated inter-picture processing. In this report, we check the improvement of the efficiency and the compatibility of proposed method. As a result of examination, we recognize that the total gain is maximally 1.2dB in PSNR. Generally, the degradation of performance in standard decoding is smaller than its gain. Also the refreshment performance is tested.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.4
• /
• pp.47-54
• /
• 1983

The performance of an intra-frame DCT/DPCM hybrid coding is investigated with the criteria of normalized mean square error and subjective test for various system parameters. It includes the prediction coefficient in transform domain, normalization factor and bit-map in block quantizer, and adaptive coding. It is shown that the generalized covariance model of image is a convenient tool for bit-map and adaptive coding, and for a fast low bit-rate coding.

• Journal of the Semiconductor & Display Technology
• /
• v.12 no.1
• /
• pp.35-39
• /
• 2013

H.264/AVC is an authoritative international video coding standard which shows code and efficiency more improved than the existing video standards. Above all, the parameter block mode of H.264/AVC significantly contributes much to high compression efficiency. However, as the occasion demands, users tend to pass while overlooking the part that can produce a little higher compression efficiency. We, taking notice of this point, are designed to bring in much higher compression efficiency by gathering up the overlooked parts. This paper suggests the algorithm that produces efficient performance improvement by using the histogram of luminance in the pixel unit (Macroblock) of respective prediction block and applying specific thresholds. The experimental results proves that the technique proposed by this paper increases the compression efficiency of the existing H.264/AVC algorithm by 0.4% without any increase in the whole encoding time and PSNR complexity.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.993-994
• /
• 2008

There are nine modes of the intra prediction for $4{\times}4$ luma blocks in H.264/AVC, each of which is identified by the prediction direction and reference pixels. Especially, mode 8 is modified to enhance coding efficiency, considering that the mode does not use left-bottom pixels although they are available. That is, we propose a modified intra prediction method of mode 8 which uses left-bottom pixels if available.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2006.07a
• /
• pp.400-400
• /
• 2006

• Journal of Multimedia Information System
• /
• v.4 no.4
• /
• pp.311-316
• /
• 2017

High Efficiency Video Coding (HEVC) is the newest video coding standard for improvement in video data compression. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. To get the best combination of the block an optimization process is performed in the encoder, called rate distortion optimization (RDO). In this work we are proposing a novel approach to enhance the overall RDO process of HEVC encoder. The proposed algorithm is performed in two steps. In the first step, like HEVC, it performs general rate distortion optimization. The second step is an extra checking where a SSIM based cost is evaluated. Moreover, a fast SSIM (FSSIM) calculation technique is also proposed in this paper.

• Journal of Broadcast Engineering
• /
• v.20 no.5
• /
• pp.782-785
• /
• 2015

In this paper, we propose a novel residual differential pulse-code modulation (RDPCM) coding technique to improve coding efficiency of screen content videos. The proposed method uses a weighted combination of adjacent residues to provide an accurate estimate in RDPCM. The weights are trained in previously coded samples by using an L1 optimization problem with the least absolute shrinkage and selection operation (LASSO). The proposed method achieves BD-rate saving about 3.1% in all-intra coding.

• ETRI Journal
• /
• v.39 no.5
• /
• pp.672-682
• /
• 2017

Video compression exploits statistical, spatial, and temporal redundancy, as well as transform and quantization. In particular, the transform in a frequency domain plays a major role in energy compaction of spatial domain data into frequency domain data. The high efficient video coding standard uses the type-II discrete cosine transform (DCT-II) and type-VII discrete sine transform (DST-VII) to improve the coding efficiency of residual data. However, the DST-VII is applied only to the Intra $4{\times}4$ residual block because it yields relatively small gains in the larger block than in the $4{\times}4$ block. In this study, after rearranging the data of the residual block, we apply the DST-VII to the inter-residual block to achieve coding gain. The rearrangement of the residual block data is similar to the arrangement of the basis vector with a the lowest frequency component of the DST-VII. Experimental results show that the proposed method reduces the luma-chroma (Cb+Cr) BD rates by approximately 0.23% to 0.22%, 0.44% to 0.58%, and 0.46% to 0.65% for the random access, low delay B, and low delay P configurations, respectively.