A new video coding standard that promises to require only half the bit rate of current approaches for the same quality has reached the first stage of approval. The successor to H.264 will be H.265, informally known as High Efficiency Video Coding or HEVC. It is anticipated that it will enable a new phase of innovation in video, from mobile devices through to Ultra-High-Definition Television.
The specification is the product of collaboration between the ITU Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. Officially known as ITU-T H.265 or ISO/IEC 23008-2, it is the successor to the widely adopted H.264/MPEG-AVC or Advanced Video Coding Standard.
Members of the ITU, the United Nations agency for information and communication technology, have agreed the standard. It has simultaneously been promoted to a Final Draft International Standard by the MPEG group.
“ITU-T H.264 underpinned rapid progression and expansion of the video ecosystem, with many adopting it to replace their own proprietary compression codecs,” said Dr Hamadoun Touré, the secretary general of the ITU. “I have no doubt that this new standard will be as effective as its predecessor in enabling the next wave of innovation in this fast-paced industry.”
The new standard is designed to take account of advancing screen resolutions and is expected to be phased in as high-end products and services outgrow the limits of current network and display technology.
There is no single reason that the new standard offers greater compression efficiency. It is the product of many improvements that contribute to a significant gain in the data compression that can be achieved for the same perceptual quality.
H.265 includes a Main profile that supports 8-bit video, a Main 10 profile with 10-bit support, and a Main Still Picture profile. Future extensions will provide for increased bit depth, offering increased colour fidelity, as well as multiview coding, which can be used for 3D applications, and scalable video coding, allowing delivery at multiple resolutions.
The still picture profile can offer a bit rate reduction of more than 40% over JPEG compression for equivalent quality. However, it will not replace higher bit-depth RAW image formats used by many photographers.
H.265 can support resolutions up to 8192x4320 pixels at 120 frames a second, for Ultra-High-Definition Television. Future work on audio coding will include support for so-called 3D Audio, enabling the sort of 22.2 channel audio that has been demonstrated with UHDTV.
Although the first commercial products to support H.265 are expected in 2013, it could be several years until it becomes broadly adopted.
Among the first applications may be on portable devices and mobile networks, which stand to benefit from lower bit-rates, while being characterised by rapid product release and replacement cycles.
Other applications are likely to include Ultra-High-Definition products and services, which will be able to take advantage of improved compression efficiency at higher resolutions.
Meanwhile, the existing H.264 standard is still being developed to support 4K resolution applications. Broadcasters are likely to rely on MPEG-4 and MPEG-2 for the foreseeable future, given the need to continue to support a large legacy of receivers.
New services and networks will benefit from the higher compression efficiency of H.265. This will allow high-definition video to be delivered using significantly less bandwidth, or enable higher resolution or frame rate video to be delivered for the same data rate.