The state-of-the-art median prediction scheme is widely used for predicting motionvectors (MVs) in recent video standards. By exploiting the spatial correlations among MVs, median prediction scheme predicts MV for cu...
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The state-of-the-art median prediction scheme is widely used for predicting motionvectors (MVs) in recent video standards. By exploiting the spatial correlations among MVs, median prediction scheme predicts MV for current block from three neighboring blocks. When MV is obtained from motion estimation, MV difference (MVD) is calculated and then transmitted. This process for predicting MV and calculating MVD is known as MV coding process. For MV coding, the performance depends on how efficient both the spatial and the temporal correlations among MVs are being exploited. Median prediction scheme applies a sophisticated way including some special rules to exploit the spatial correlations, however the temporal correlations among successive MVs are not exploited. In this paper, a new algorithm named MV pattern matching (MV-PM) exploiting both the spatial and temporal correlations is proposed. Various kinds of experimental results show that the proposed MV-PM algorithm outperforms the median prediction and the other related prediction schemes. (C) 2011 Elsevier Inc. All rights reserved.
H.264/MPEG4-AVC is the latest video codec provided by the Joint Video Team, gathering ITU-T and ISO/IEC experts. Technically there are no drastic changes compared to its predecessors H.263 and MPEG-4 part 2. It howeve...
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ISBN:
(纸本)9780819466211
H.264/MPEG4-AVC is the latest video codec provided by the Joint Video Team, gathering ITU-T and ISO/IEC experts. Technically there are no drastic changes compared to its predecessors H.263 and MPEG-4 part 2. It however significantly reduces the bitrate and seems to be progressively adopted by the market. The gain mainly results from the addition of efficient motion compensation tools, variable block sizes, multiple reference frames, 1/4-pel motion accuracy and powerful Skip and Direct modes. A close study of the bits repartition in the bitstream reveals that motion information can represent up to 40% of the total bitstream. As a consequence reduction of motion cost is a priority for future enhancements. This paper proposes a competition-based scheme for the prediction of the motion. It impacts the selection of the motionvectors, based on a modified rate-distortion criterion, for the Inter modes and for the Skip mode. Combined spatial and temporal predictors take benefit of temporal redundancies, where the spatial median usually fails. An average 7% bitrate saving compared to a standard H.264/MPEG4-AVC codec is reported. In addition, on the fly adaptation of the set of predictors is proposed and preliminary results are provided.
This paper proposes a new motionvector expression method named merge mode with motionvector difference (MMVD) for future video coding standards. In the previous standards, two approaches arc typically used for motio...
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ISBN:
(纸本)9781728163956
This paper proposes a new motionvector expression method named merge mode with motionvector difference (MMVD) for future video coding standards. In the previous standards, two approaches arc typically used for motionvector representation. In the first one, the motionvector is derived from neighboring blocks and is directly used for motion compensation (merge mode in IIEVC), and in the other one, the motionvector is represented with motionvector predictor and a difference (adaptive motionvector prediction;AMVP in HEVC). The merge mode benefits by saving bits for representing motion information. The AMVP represents more accurate motion information but it needs to signal the motion difference information, which consumes additional bits. MMVD provides a compromised solution for the trade-off between motionvector accuracy and its overhead. MMVD can improve motionvector accuracy by introducing a simplified motionvector representation. The results show that the proposed method improves coding efficiency of VVC with an average of 0.51% in BD-rate saving.
Context modeling algorithm for motionvectors presented in this paper is an improvement of the current one used in Context-Based Adaptive Binary Arithmetic coding (CABAC). In our algorithm for coding the vertical moti...
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ISBN:
(纸本)9781424418343
Context modeling algorithm for motionvectors presented in this paper is an improvement of the current one used in Context-Based Adaptive Binary Arithmetic coding (CABAC). In our algorithm for coding the vertical motionvector difference (MVD) components, we take advantage of the coded data of the horizontal MVD components as one of the references for context modeling. Moreover, we adopt different schemes according to the encoding partition sizes. For small block sizes, we only consider the correlation among the neighboring blocks. Whereas for large block sizes, we also employ the inter-correlation between the two MVD components in the current block to improve the probability estimation of symbols. These strategies enhance the accuracy of the context model selection in motion vector coding, thus elevate the efficiency of the context-based arithmetic coder. Experimental results show that the proposed algorithm improves compression performance compared to the original CABAC scheme.
Error protection and concealment of motionvectors are of prime concern when video is transmitted over variable-bandwidth error-prone channels, such as wireless channels. In this paper, we investigate the influence of...
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ISBN:
(纸本)0819455601
Error protection and concealment of motionvectors are of prime concern when video is transmitted over variable-bandwidth error-prone channels, such as wireless channels. In this paper, we investigate the influence of corrupted motionvectors in video coding based on motion-compensated temporal filtering, and develop various error protection and concealment mechanisms for this class of codecs. The experimental results show that our proposed motion vector coding technique significantly increases the robustness against transmission errors and generates performance gains of up to 7 dB compared with the original coding technique at the cost of less than 4% in terms of rate. It is also shown that our proposed spatial error-concealment mechanism leads to additional performance gains of up to 4 dB.
Depth maps are becoming increasingly important in the context of emerging video coding and processing applications. Depth images represent the scene surface and are characterized by areas of smoothly varying grey leve...
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ISBN:
(纸本)9781467372589
Depth maps are becoming increasingly important in the context of emerging video coding and processing applications. Depth images represent the scene surface and are characterized by areas of smoothly varying grey levels separated by sharp edges at the position of object boundaries. To enable high quality view rendering at the receiver side, preservation of these characteristics is important. Lossless coding enables avoiding rendering artifacts in synthesized views due to depth compression artifacts. In this paper, we propose a binary tree based lossless depth coding scheme that arranges the residual frame into integer or binary residual bitmap. High spatial correlation in depth residual frame is exploited by creating large homogeneous blocks of adaptive size, which are then coded as a unit using context based arithmetic coding. On the standard 3D video sequences, the proposed lossless depth coding has achieved compression ratio in the range of 20 to 80.
We propose a derivation scheme of a motionvector for interlace format. The adjustment of the vertical component of a chroma MV for 4: 2: 0 format and the adjustment of the vertical component of a luma prediction MV a...
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ISBN:
(纸本)9781457720482
We propose a derivation scheme of a motionvector for interlace format. The adjustment of the vertical component of a chroma MV for 4: 2: 0 format and the adjustment of the vertical component of a luma prediction MV are introduced in order to remove inconsistency between the current derivation process of motionvector predictor and the nature of interlace format in HM4.0. The proposed scheme achieves up to 1.0dB PSNR improvements in chroma components and up to 3.4% bit-rate reduction.
motionvectors correlate very well with other neighboring motionvectors. Thus, many macroblocks have zero residual motionvectors within their blocks after differential pulse coded modulation using their individually...
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motionvectors correlate very well with other neighboring motionvectors. Thus, many macroblocks have zero residual motionvectors within their blocks after differential pulse coded modulation using their individually predicted motionvectors. Motivated by this observation, we develop a new joint encoding scheme of motionvectors by defining a new macroblock coding mode called pooled zero motionvector difference coding to jointly code such cases more efficiently. Experimental results with several well-known video test sequences verify that the proposed method improves the coding efficiency up to 6.2% compared to the H. 264 vertical bar advanced video coding (AVC). (c) 2008 Society of Photo-Optical Instrumentation Engineers.
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