Multiview Video Coding Encoder Research Articles

Early DIRECT mode decision based on all‐zero block and rate distortion cost for multiview video coding

The exhaustive variable-block-size mode decision can efficiently remove the redundancies among the multiview videos, while it also leads to significant increase of computational complexity in the multiview video coding (MVC) encoder, and the high encoding complexity becomes a bottleneck for the MVC encoder to achieve real-time multimedia applications. To address this bottleneck, many fast mode decision methods have been proposed. However, most of them are only suitable for optimising the encoding complexity of the odd views of the MVC encoder. In this study, based on the property of the all-zero block and rate distortion (RD) cost of the DIRECT mode as well as the correlations between the current macroblock (MB) and its spatial–temporal nearby MBs, an early DIRECT mode decision method is proposed for reducing the encoding complexity of the MVC. Experimental results show that the proposed method achieves 48.25 and 55.64% on average encoding time saving for the even and odd views, respectively, whereas the RD performance degradation is quite acceptable. In summary, the proposed method efficiently reduces the encoding complexity for the MVC encoder.

Fast macroblock encoding algorithm based on rate-distortion activity for multiview video coding

Multiview video coding (MVC) is the appendix H of H.264/AVC, and it requires a great amount of time to compress multiple viewpoints׳ video with complex prediction structures. To reduce the whole computational complexity of MVC, this paper proposes a fast macroblock (MB) encoding algorithm based on rate-distortion (RD) activity, and it includes the fast mode decision and the fast motion/disparity estimation. First, the RD activity type of the current MB is calculated by utilizing the Skip/Direct RD cost and the average RD costs of classified MB modes. Then, through utilizing the RD activity type and RD costs of the estimated modes, the selection of candidate modes, the early decision of Skip/Direct mode, and the reduction of Inter8×8 mode estimation are all presented in the fast mode decision. By using the RD activity type and the correlations of vectors, the selection of search center and the prediction of search range are introduced in the fast motion/disparity estimation. In addition, the proposed algorithm can be applied to temporal and inter-view views as well as anchor and non-anchor frames. An experiment with a wide range of video scenes, camera setups and quantization parameters was implemented, and the results confirmed that the proposed algorithm can reduce the encoding time significantly while maintaining a similar RD performance as the original MVC encoder. Compared to the state-of-the-art algorithms, the proposed algorithm also demonstrated better performances in the various test cases.

Global-local correlation-based early large-size mode decision for multiview video coding

Multiview video coding (MVC) is a recent extension of H.264/AVC, and it consumes huge encoding time to select the optimal macroblock (MB) mode, among different size candidate modes. As compared with the small-size mode (Inter16 × 8, Inter8 × 16, Inter8 × 8, Intra8 × 8, and Intra4 × 4), the large-size mode (Skip/Direct, Inter16 × 16, and Intra16 × 16) occupies most of the MB mode proportion with much less computational com- plexity. Thus, if the large-size mode could be early decided as the optimal MB mode, the complexity of mode decision could be effectively reduced. In this work, an early large-size mode decision algorithm is proposed based on the global correlation of rate-distortion (RD) costs between neighbor views and the local correlation of RD costs among candidate modes. Average RD costs of large-size and small-size MB modes in the neighbor view are employed as a global reference for the threshold of early decision. And RD costs of estimated modes are used to calculate the local adjustment for the threshold. Experimental results demonstrate that the proposed algorithm can significantly reduce the whole encoding time while maintaining an RD performance similar to that of the original MVC encoder. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10 .1117/1.JEI.23.1.013027)

Fast Mode Decision Using Global Disparity Vector for Multiview Video Coding

Since multiview video coding (MVC) based on H.264/AVC uses a prediction scheme exploiting inter-view correlation among multiview video, MVC encoder compresses multiple views more efficiently than simulcast H.264/AVC encoder. However, in case that the number of views to be encoded increases in MVC, the total encoding time will be greatly increased. To reduce computational complexity in MVC, a fast mode decision using both Macroblock-based region segmentation information and global disparity vector among views is proposed to reduce the encoding time. The proposed method achieves on the average 1.5∼2.9 reduction of the total encoding time with the PSNR (Peak Signal-to-Noise Ratio) degradation of about 0.05dB.