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H.265 (HEVC) Codec Approved by ITU

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By Matt Brennesholtz

Standards – The proposed High Efficiency Video Coding (HEVC) Codec, also known as H.265, has been approved by the ITU after roughly nine years of development effort. This builds upon and replaces Emmy award winning ITU-T H.264 / MPEG-4 Advanced Video Coding (AVC).  This previous standard had in turn replaced multiple proprietary codecs and currently encodes about 80 percent of all Internet video.

The current AVC standard is deployed in products and services from companies including Adobe, Apple, BBC, BT, France Telecom, Intel, Microsoft, Motorola, Nokia, Polycom, Samsung, Sony, Tandberg, Toshiba and others to deliver high definition video images over broadcast television, cable TV, a variety of direct-broadcast satellite-based television services, Blu-Ray disc formats, mobile phones, videoconferencing tools, digital storage media, and Internet Protocol television (IPTV). It remains the most deployed global video compression standard. The H.264 standard was authorized in 2008 for use in the encoding in the digital terrestrial broadcasting in the US although it is not currently used for that.

The key improvement in HEVC compared to AVC encoding is the reduction in bit rate of about 50 percent without an accompanying reduction in image quality. This is key for video over IP applications such as the Internet, where the network bandwidth is limited. While Internet providers are increasing the available bandwidth rapidly, end users are increasing their use of bandwidth rapidly as well, through more streaming video, more video downloads and downloads of higher resolution video. Currently it is estimated that 50 percent of all Internet bandwidth is dedicated to video.

HEVC is by no means a finished standard. In fact, the parts that are finished haven’t even been published yet since the vote to approve it took place on January 25th. What has happened is ITU-T’s Study Group 16 has agreed first-stage approval of Recommendation ITU-T H.265, which will also be ISO/IEC 23008-2. The standard is the product of collaboration between the ITU Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG), hence the two different standards numbers.

Companies including ATEME, Broadcom, Cyberlink, Ericsson, Fraunhofer HHI, Mitsubishi, NHK, NTT DOCOMO and Qualcomm have already shown implementations of HEVC. The new standard  includes a ‘Main’ profile that supports 8-bit 4:2:0 video, a ‘Main 10’ profile with 10-bit support, and a ‘Main Still Picture’ profile for still image coding that employs the same coding tools as a video ‘intra’ picture.

As I said, HEVC isn’t finished yet. The ITU/ISO/IEC Joint Collaborative Team on Video Coding (JCT-VC) will continue work on a range of extensions to HEVC, including support for 12-bit video as well as 4:2:2 and 4:4:4 chroma formats. Another important element of this work will be the progression of HEVC towards scalable video coding. The three bodies will also work within the Joint Collaborative Team on 3D-Video (JCT-3V) on the extension of HEVC towards stereoscopic and 3D video coding.

4K/Ultra-HD TV sets have gotten a lot of press recently, including at Insight Media.  There has also been a lot of press about the lack of 4K content to show on these sets.  One of the issues of 4K content is bandwidth — it takes more bandwidth to encode the 4x pixel content of Ultra-HD compared to 1080p, although not 4x the bandwidth. Broadcasters have been very reluctant to use more bandwidth than necessary for a given channel; they would rather use bandwidth to broadcast additional channels to attract additional viewers, advertisers and revenue. With HEVC, the needed bandwidth is reduced by roughly 50 percent compared to AVC. This means 4K content compressed with HEVC will take less bandwidth than 1080p content compressed with AVC. Of course, bandwidth is bandwidth and the content providers may decide to provide twice as many choices of HDTV content when HEVC is implemented rather than provide the same number of 4K choices with HEVC as there are HD choices with AVC. Probably, of course, it will be a mixture of both, plus some AVC SD content will be upgraded to HEVC HD content. Whatever happens, everyone seems to be a winner: consumers with more choices of better quality content; broadcasters, including terrestrial, cable, satellite and Internet, able to provide more and better choices; and bandwidth providers getting a little relief in the relentless requirement to provide more bandwidth.

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