Sangjin Hahm

Daejeon University, Daiden, Daejeon, South Korea

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Publications (15)1.82 Total impact

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    ABSTRACT: This 255th issue offers two technical articles contributed by Korean Broadcasting System and Turkish Radio and Television Corporation together with profiles of ABU members in Vietnam. The KBS article shares practical experiences regarding the implementation of 4K using DVB-T2 technology and how to deliver 4K television signals to television viewers terrestrially. The article reports the success and the potential of the service. The TRT article describes the implementation of a building block of a system to enhance the efficiency and effectiveness of the production of radio programmes and broadcasting in all stages. A report on a six-day Technical Advisory Service to the Palestine Broadcasting Commission is included together with details of the ABU Festival of Technology Webinars that was held over August and September. This issue also provides reports on BroadcastAsia2013, the DAB+ Technology Workshop held in Hanoi, the Central Asia Media Forum held in Bishkek and the 2013 Pacific Media Partnership Conference held in Vanuatu. In addition, our usual features, news from region, updates on digital broadcasting and new broadcasting equipment, make up the rest.
    PP 2412/11/2012 (031331) • ISSN 0126-6209 edited by Amal Punchihewa, 10/2013; ABU., ISBN: PP 2412/11/2012 (031331) • ISSN 0126-6209
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    ABSTRACT: 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.
    IEEE Transactions on Circuits and Systems for Video Technology 01/2013; 23(9):1542-1554. · 1.82 Impact Factor
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    ABSTRACT: New broadcasting services such as 3DTV and UHDTV are turning up and catching the public attention, because people nowadays like to have more realistic watching experience in TV. However, terrestrial broadcasters have difficulties in launching them, because new terrestrial broadcasting services necessarily need new frequency allocation. As frequency is public goods and the frequency for broadcasting is limited. To solve the lack of frequency, we designed hybrid 3DTV broadcasting technology combining terrestrial broadcasting channel and broadband network. For the hybrid 3DTV, the left view is transmitted through the terrestrial broadcasting channel and the right view is delivered using the internet. The difference of two transport networks causes inevitable receiving time delay. To synchronize the left view and the delayed right view by frame accuracy, we insert SMPTE time code into the left and right elementary streams respectively and transmit them. To verify the validity and practicality of hybrid 3DTV service, we performed live broadcasting of 'IAAF World Championships' in August 2011 via hybrid 3DTV technology.
    Broadband Multimedia Systems and Broadcasting (BMSB), 2012 IEEE International Symposium on; 01/2012
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    ABSTRACT: 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.
    Broadband Multimedia Systems and Broadcasting (BMSB), 2012 IEEE International Symposium on; 01/2012
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    ABSTRACT: 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.
    Seventh International Conference on Advances in Pattern Recognition, ICAPR 2009, Kolkata, India, 4-6 February 2009, Proceedings; 01/2009
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    ABSTRACT: In this paper, a low complexity encoding scheme for coarse grain scalability in Scalable Video Coding is proposed. The coarse grain scalability is a kind of SNR quality scalability in Scalable Video Coding. It utilizes the similar coding scheme with spatial scalability using inter-layer prediction and has a base layer and several enhancement layers. While CGS scalability supports video at the different quality levels, the computational complexity also dramatically increases as the number of quality levels increases. The proposed method exploits the statistics of residuals between current and reference blocks computed using the macroblock mode predicted from the previous quality layer. Since the quality between consecutive layers is significantly different, the block mode from the previous layer cannot be utilized directly. To test how efficient is some modes in the current layer, the statistical hypothesis testing for the variances of the residual sub-blocks is performed. If the variances tests for sub-block of residuals are accepted, the mode from the previous layer is regarded as the optimal in the current layer. Otherwise, one of other modes is recommended according to the result of the statistical test. The proposed method reduces the total encoding time when three CGS scalability layers are encoded up to 51%. However, the quality degradation and bit-rate increment of the each layer are negligible.
    Visual Information Engineering, 2008. VIE 2008. 5th International Conference on; 09/2008
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    ABSTRACT: Scalable Video Coding (SVC) can be applicable in mobile broadcasting environment due to the flexibility of spatial, temporal and quality scalability. Recently, SVC technology becomes mature rapidly but its reference SW encoder isn't optimized yet. Therefore, we have developed a real-time SW SVC encoder for broadcasting. In this paper, we show our SVC encoder that can provide two spatial layers: QVGA(320 x 240) and VGA(640 x 480). The base layer can be fully compatible with H.264/AVC. Our encoder is performing real-time operation on a normal PC by optimizing SVC algorithm.
    Consumer Communications and Networking Conference, 2008. CCNC 2008. 5th IEEE; 02/2008
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    ABSTRACT: The AVC|H.264 video coding standard adopts 4x4 integer transform on residuals between an original pixel block and its motion-compensated pixel block to make better prediction for the improvement of temporal redundancy reduction. Detecting all-zero blocks prior to integer transform in AVC|H.264 was taken into account as an important step in fast encoding process. Different from the previous approaches to early detection of all-zero blocks based on sums of absolute differences and quantization steps, this paper designed a linear classifier with additional features available before integer transform. With significant features to detect all-zero IT coefficients, the linear classifier improved detection accuracy so that skipping the integer transform process could accelerate the encoding process and minimize the encoding performance drop in PSNR values. The linear classifier is trained with large amount of training data and tested by video sequences with different characteristics. Experimental results demonstrated that through a wide range of quantization parameters and video sequences the proposed approach improved detection of all-zero blocks over the conventional approach with negligible amounts of PSNR degradation.
    Digital Image Computing Techniques and Applications, 9th Biennial Conference of the Australian Pattern Recognition Society on; 01/2008
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    ABSTRACT: The H.264MPEG-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.
    Broadband Multimedia Systems and Broadcasting, 2008 IEEE International Symposium on; 01/2008
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    ABSTRACT: 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.
    Broadband Multimedia Systems and Broadcasting, 2008 IEEE International Symposium on; 01/2008
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    Bumshik Lee, Munchurl Kim, Sangjin Hahm
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    ABSTRACT: 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.
    Proc SPIE 01/2008;
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    ABSTRACT: MPEG Scalable Video Coding (SVC), which also known as H.264 Scalable Extension, makes video adaptation more flexible to meet user consumption preferences, application requirements, and also varying network conditions. An SVC bit stream consists of one or more scalable layers that form hierarchical dependency such that a layer has dependency on its lower layers. Therefore a layer cannot be decoded perfectly if all of its lower layers are not decoded a priori. In this paper, we propose layered protection, which is a partial protection scheme, for SVC bit streams by fully utilizing layer dependency characteristics of SVC. Layered protection scheme can achieve protection degree as high as that of given by protection of entire SVC bit streams (referred as total protection). Therefore it reduces complexity for protecting/unprotecting SVC bit streams. We use a modified Structural Similarity Index (SSIM) to show effectiveness of layered protection scheme in term of visual perception degradation. Our experiments show that layered protection scheme is not only effective in term of visual degradation, but also efficient in term of computational complexity. For our test videos, in average, we only need to protect 42.45% of input bit stream to achieve the same visual perception degradation as that of given by total protection (protecting 100% of input bit stream).
    Visual Information Engineering, 2008. VIE 2008. 5th International Conference on; 01/2008
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    ABSTRACT: We introduce an efficient mode selection method in the enhancement layers of spatial scalability in the SVC encoder by selectively performing the inter-layer residual coding of the SVC. The proposed method is to make an analysis of the characteristics of integer transform coefficients for the subtracted signals for two residuals from lower and upper spatial layers. Then it selectively performs the inter-layer residual prediction coding in the spatial scalability if the SAD values of inter-layer residuals exceed adaptive threshold values. Therefore, by classifying the residuals according to the properties of integer-transform coefficients only with the SAD of inter-layer residual signals between two layers, the SVC encoder can perform the inter-layer residual coding selectively, thus significantly reducing the total encoding time with 51.2% in average while maintaining the RD performance with negligible amounts of quality degradation.
    Proc SPIE 01/2008;
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    ABSTRACT: 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.
    Advanced Communication Technology, The 9th International Conference on; 03/2007
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    ABSTRACT: 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.
    Advanced Communication Technology, The 9th International Conference on; 03/2007