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R&D / Technology – Next-Generation High Efficiency Video Coding (HEVC) Technology

Advanced Video Compression Technology that Is Gradually becoming Global Standard.

Overview

Next-Generation High Efficiency Video Coding (HEVC) Technology has twice the performance of AVC/H.264.

Modern society is able to easily access a rich array of video content, such as high-definition broadcasting, movies on Blu-ray Disc and video streaming. The image quality advances in these various video systems would not be possible without video coding technology. Video coding technology makes it possible to compress large volumes of video data without losing picture quality, for easy distribution over the Internet or other media, and for recording long hours of video with recorders, etc. Many video systems currently use MPEG-2 or MPEG-4 AVC/H.264 video formats, as governed by the ISO/IEC*1 and ITU-T*2 international standards. Mitsubishi Electric is taking part in the process of deciding the next standard. Together with the NHK Science & Technology Research Laboratories we are studying "next-generation high-compression video encoding technology," which aims to achieve approximately four times the compression performance of MPEG-2 and approximately twice that of MPEG-4 AVC/H.264. We are also working to get this technology adopted as the new standard.

Block size optimization based on the image structure

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In the case of digital broadcasting, for example, video has 30 frames per second. But recording all 30 frames of the screen as is results in an extremely large amount of data. For that reason, only residual data that subtracts the previous frame from the current frame is encoded—that is, only the parts of the frame where there is some motion—which makes it possible to compress the video while maintaining picture quality. To estimate this motion, MPEG-4 AVC/H.264 divides the frame into blocks of 16 × 16 pixels and detects motion within each block. However, our high-compression video encoding technology does not use a fixed block size, and can instead change flexibly according to frame structure. Blocks are larger in even parts like landscapes, and smaller in more complex parts. This flexibility reduces the amount of data recorded as differential, greatly increasing the compression ratio.

Development Notes

We developed this new coding technology as the next standard.

Yusuke Itani
High-Efficiency Encoding Format Team
Multimedia Encoding and Distribution Technology Division

The concept itself of adaptive block size derivation has been discussed in a number of forums, including academic societies. Achieving this ability, however, requires solving many issues, such as what type of block pattern to use to find differentials in various frames, and how to more efficiently detect screen movement. Development has been a process of repeatedly watching video directly which has been compressed for test purposes and checking to see if the motion is smooth or any block noise can be seen, and then fixing any problems. More than 15 types of video were used for the tests, because we cannot claim success if we don’t get a uniform compression ratio and picture quality for all types of video. Because we had so many test videos, just checking them took quite a bit of time.

Mitsubishi Electric has developed video codec systems for more than 20 years.

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We have pursued the current development by bringing together Mitsubishi Electric video encoding experts from Japan and abroad. The know-how and technology we have built up over many years in the development of the MPEG-4 AVC/H.264 codec has gone into all aspects of the current development. Mitsubishi Electric has also been continuously involved in the establishment of standards for over 20 years, including H.261 when there were still few enterprises participating, and MPEG-2, which is presently in wide use. R&D as part of the standardization process is somewhat different from ordinary product development. Our experience taking part in such activities from the early days of MPEG has been a valuable asset for Mitsubishi Electric.

HEVC Technology will be used for various applications all over the world.

Many initiatives are underway for greater picture quality, such as the Super High-Vision ultra-high-resolution video format promoted by NHK, and 4K × 2K TV with approximately four times the pixel count of Full HD. As we head into an era of 3D and other high-resolution imaging, video compression technology is going to be more and more important. We believe there will be increasing demand for extended video recording, not just for entertainment but also for applications like 24-hour security monitoring, so this technology has many possibilities. Our next-generation high-compression video coding technology still needs brushing up, and the process of establishing a new standard has just begun. It will be a long road to establish the standard and then put it into practical use, but we will continue our development efforts so that this technology will be used in next-generation video systems.

Mitsubishi Electric is pursuing this development with Japan Broadcasting Corporation (NHK).
*1
ISO : International Organization for Standardization
IEC : International Electrotechnical Commission
*2
ITU-T : International Telecommunication Union Telecommunication Standardization Sector
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