Sangjin Hahm

A fast mode selection scheme in inter-layer prediction of H.264 Scalable Extension coding

We propose a fast inter-layer mode decision method by utilizing coding information of base layer upward its enhancement layer in scalable video coding (SVC), also called MPEG-4 part 10 Advanced Video Coding Amendment 3 or H.264 Scalable Extension (SE). In this paper, when the motion vectors from the base layer have zero motion (0, 0) in inter-layer motion prediction or the Integer Transform coefficients of the residual between current MB and the motion compensated MB by the predicted motion vectors from the base layer are all zero, the block mode of the corresponding block to be encoded in the enhancement layer is determined to be the 16*16 mode. In addition, if the predicted mode of the MB to be encoded at the enhancement layer is not equal to the 16 *16 mode, then the rate-distortion optimization is only performed on the reduced numbers of candidate modes which are same or smaller partitioned modes. Our proposed method exhibits the complexity reduction in encoding time up to 70%. Nevertheless, it shows negligible PSNR degradation and bit rate increase up to 0.2 MB and 0.71 % respectively.

A network-adaptive SVC Streaming Architecture

For video streaming, we must consider terminal and network characteristics. The scalable video coding (SVC) can represent video bitstreams in different scalable layers for flexible adaptation to terminal and network characteristics. The SVC can allow for extraction of appropriate partial bitstreams to meet specific target bitrates and spatial resolutions from an SVC bitstream with several spatial, temporal and quality scalability layers. Moreover, the extraction process is fast, so it is possible to extract the partial video streams online to cope with the delivery networks with changing characteristics such as bandwidth etc. With all the advantages of SVC, we design and implement a network-adaptive SVC streaming system to extract partial SVC bitstreams to meet the required target bitrates and spatial resolutions. We present the implementation of our SVC streaming system with experimental results.

An efficient block mode decision for temporal scalability in scalable video coding

In this paper, a fast intermode decision scheme which is suitable for the hierarchical B-picture structure in which much computational power is spent for combined variable block sizes and bi-predictive motion estimation is introduced. The hypothesis testing considering the characteristics of the hierarchical B-picture structure in the proposed method is performed on 16x16 and 8x8 blocks to have early termination for RD computation of all possible modes. The early termination in intermode decision is performed by comparing the pixel values of current blocks and corresponding motion-compensated blocks. When the hypothesis tests are performed, the confidence intervals to accept the null hypothesis or not are decided according to the temporal scalability levels under the consideration of properties of hierarchical B-pictures. The proposed scheme exhibits effective early termination behavior in intermode decision of temporal scalabilities and leads to a significant reduction up to 69% in computational complexity with slight increment in bit amounts. The degradation of visual quality turns out to be negligible in terms of PSNR values.

A fast 4x4 intra mode decision for inter frame coding in H.264|MPEG-4 Part 10

The H.264\MPEG-4 Part 10 (AVC) standard incorporates an intra prediction into inter frame coding. However, this leads to excessive increase of encoding time. This paper presents a fast intra mode decision and intra prediction algorithm to reduce encoding time. Basically, the proposed algorithm designs the skip condition for candidate modes of 4times4 intra prediction to be dependent of the content types of sequences and the context of pre-encoded adjacent blocks in terms of intra prediction-related probabilities. The content and context adaptive conditional probability table for the most probable modes is generated during an I- frame coding and is exploited for the intra mode decision in the following P frames until the next I-frame. The experimental results show that the total encoding time saving can be achieved up to maximally 43.17% with negligible PSNR drop and bitrate increase compared to the joint model (JM) reference software of AVC.

Dependent Quantization for Scalable Video Coding

Quantization in video coding plays an important role in controlling the bitrate of compressed bitstreams to adjust with the allowed bandwidth of delivery networks and storage. Since scalable video coding (SVC) being currently standardized exhibits highly dependent coding nature not only between frames but also in the lower and higher layers, we propose a dependent quantization scheme for SVC and compare its performance in visual qualities and bitrates with the current technique in JSVM reference software. The experimental results show that the dependent quantization outperforms the current technique in JSVM reference software with 0.5 ~ 1.25 dB PSNR increment or 5 ~ 20% bits saving for the enhancement layer of SVC.

A Hybrid Stereoscopic Video Coding Scheme Based on MPEG-2 and HEVC for 3DTV Services

Recently, 3DTV has drawn much attention as a new broadcasting service. In spite of technical advances in 3DTV broadcasting services, there are two barriers that hinder the new services from being launched for terrestrial broadcasting: the lack of available bandwidth for transmission of additional-view video via terrestrial channel and backward compatibility with the legacy 2-D HDTV services. As an alternative, a hybrid stereoscopic video coding scheme is proposed for a stereoscopic 3DTV service, where one-view video is transmitted through the legacy broadcasting systems and the other one is delivered via broadband networks to which TV terminals are connected. In this paper, the proposed hybrid stereoscopic video coding scheme incorporates an MPEG-2 codec for backward compatibility with a legacy 2-D HDTV service and an HEVC codec with inter-view prediction coding as an extension to encode additional-view video sequences with high coding efficiency. The proposed inter-view prediction coding scheme in the extended HEVC incorporates an advanced motion and disparity vector prediction (AMDVP) method for enhanced motion- and disparity-compensated coding. The experimental results demonstrate that the proposed hybrid stereoscopic video coding scheme achieves an average coding efficiency of 38.22% (32.86%) in BD-rate or 1.394 dB (1.235 dB) in BD-PSNR for the out-band (in-band) scenario.

An extended AMVP scheme in HEVC with MPEG-2 for a hybrid stereoscopic encoder

A hybrid stereoscopic broadcasting service is considered a possible solution to the lack of frequency bandwidth for transmission of additional view sequences and to the backward compatibility for the existing MPEG-2 based DTV services. In this paper, a hybrid stereoscopic encoder based on MPEG-2 and HEVC is first considered where left-view sequences are encoded by MPEG-2 to provide the backward compatibility while right-view sequences are encoded by HEVC for delivery over Internet. In the hybrid stereoscopic encoder, we propose an inter-view coding scheme between the left- and right-view sequences to enhance the coding performance of HEVC for right-view sequences. Therefore, in this paper, an extension to HEVC is made with an inter-view coding scheme by having disparity based motion-compensated prediction. For this, MPEG-2 motion vectors from left-view sequences and global disparity vectors between two-view sequences are utilized. The experimental results show that the proposed hybrid stereoscopic encoder achieves average 37.75% coding gain in BDBR compared with the performance of HEVC simulcast encoding for right-view sequences.

Block-Mode Classification Using SVMs for Early Termination of Block Mode Decision in H.264|MPEG-4 Part 10 AVC

In this paper, a two-stage block-mode classification scheme of H.264|MPEG-4 Part 10 AVC is presented as a pattern classification approach using SVMs in order to reduce high computational complexity of its encoders. For the block-mode classification, the feature vectors for each macroblock are formed for the SVMs with SATD and CBP values to detect the large and small block modes. From the experimental results, the proposed scheme yields 80% and 95% of the correct classification rate in average for the first and second stage, which has led to from 35% to 55% reduction in the total encoding time while maintaining negligible amounts of bit rate increases and PSNR drops for test sequences with QCIF, CIF, and 4CIF resolutions and various quantization parameter values.

Laboratory Measurement to Provide Threshold of Visibility for Terrestrial 4K-UHDTV Broadcasting based on HEVC over DVB-T2

In this study, HEVC over DVB-T2 systems with a bandwidth of 6 MHz is considered, particularly for the terrestrial 4KUHDTV broadcasting service in the Republic of Korea. The threshold of visibility carrier-to-noise power ratio (ToV C/N) and the receiver minimum required input level (sensitivity) for satisfying the subjective picture failure (SPF) condition are measured in the laboratory. It is observed, for transmitting 26.37 Mbps data stream correctly, that ToV C/N is 18.8 dB on average, and the receiver sensitivity is varied from minimum -84.2 dBm to maximum –80.0 dBm. Based on the results, the receiver noise floor is calculated by –100 dBm on average. Keyword : HEVC over DVB-T2, Threshold of Visibility, Receiver Sensitivity, Laboratory Measurement, Subjective Picture Failure, Physical Layer Performance Metric a) KBS 미래기술연구소(Future Technology Research Institute, KBS) ‡Corresponding Author : 전성호(Sungho Jeon) E-mail: jeonsh@kbs.co.kr Tel: +82-2-781-5259 ORCID: http://orcid.org/0000-0002-0417-6906 ※ 이 논문의 연구결과 중 일부는 “IWAIT 2016”에서 발표한 바 있음. ※ 본 연구는 미래창조과학부 국책과제 ‘FTN기반 유무선 방송시스템 고도화 기술 개발[B0101-15-1362]’ 지원 사업의 결과로 수행되었음. ・Manuscript received March 15, 2016; Revised May 9, 2016; Accepted July 12, 2016. 특집논문 (Special Paper) 방송공학회논문지 제21권 제4호, 2016년 7월 (JBE Vol. 21, No. 4, July 2016) http://dx.doi.org/10.5909/JBE.2016.21.4.506 ISSN 2287-9137 (Online) ISSN 1226-7953 (Print) 전성호 외 4인: HEVC over DVB-T2 기반 지상파 4K-UHDTV 방송을 위한 양시청 기준값 실험실 테스트 결과 507 (Sungho Jeon et al.: Laboratory Measurement to Provide Threshold of Visibility for Terrestrial 4K-UHDTV Broadcasting based on HEVC over DVB-T2)

A Fast 4X4 Intra Prediction Method using Motion Vector Information and Statistical Mode Correlation between 16X16 and 4X4 Intra Prediction In H.264|MPEG-4 AVC

H.264| MPEG-4 AVC is a new video codingstandard defined by JVT (Joint Video Team) which consists of ITU-T and ISO/IEC. Many techniques are adopted fur the compression efficiency: Especially, an intra prediction in an inter frame is one example but it leads to excessive amount of encoding time due to the decision of a candidate mode and a RDcost calculation. For this reason, a fast determination of the best intra prediction mode is the main issue for saving the encoding time. In this paper, by using the result of statistical relation between intra and intra predictions, the number of candidate modes for intra prediction is reduced. Firstly, utilizing motion vector obtained after inter prediction, prediction of a block mode for each macroblock is made. If an intra prediction is needed, the correlation table between and intra predicted modes is created using the probability during each I frame-coding process. Secondly, using this result, the candidate modes for a intra prediction that reaches a predefined specific probability value are only considered in the same GOP For the experiments, JM11.0, the reference software of H.264|MPEG-4 AVC is used and the experimental results show that the encoding time could be reduced by 51.24% in maximum with negligible amounts of PSNR drop and bitrate increase.