HEVC (High Efficiency Video Coding) or even sometimes H.265 is, of course, the video compression standard that has been lined up as a successor to H.264/MPEG-4. It’s had a complicated gestation which has seen not one, but two standards bodies (MPEG and VCEG) join forces and come up with no less than eight working draft specifications so far.
Essentially it works in the same way as H.264 (we covered this briefly in "H.265 is the new H.264"). Its main goals are to reduce bitrate requirements by half over its predecessor, while producing images of comparable picture quality. It’s also been specced to support higher resolutions (up to 8k) and leverage advances in parallel processing methods.
The last draft standard was released in July, with products based on that astonishingly enough appearing at IBC only a couple of months later. ATEME showed encoders running the draft spec and throwing 4k images onto Toshiba screens, the result being 4k content displayed at 60fps in 11-15Mbps bandwidth.
The company admitted that the products on show were basically placeholders and would be changed come January and the Final Draft, when further efficiencies may well be possible. Harmonic, Ericsson and a number of others have also been showing the technology at work.
The last is interesting, because HEVC is considered very much to be a key technology for mobile. It is more computationally expensive than H.264 and will possibly have a consequent dramatic impact on battery lives, but combined with 4G networks it looks set to really unlock the potential of video on mobile platforms.
Of course, mobile won’t be serving 4k for a while, and in fact a lot of the heavy lifting work HEVC initially does will be in the HD world. Broadcasters, once they’ve launched HEVC set-top boxes (and rumours are that BSkyB is already working on it), then have the choice between taking advantage of double the compression ratio to double the picture quality of the HD channels they already broadcast, or effectively squashing two HD channels into the space that one currently takes up under H.264 and launch new channels. Broadcasters being broadcasters most of them will do the latter.
It’s interesting though to note that BSkyB’s own technical requirements for the second generation of H.264 encoding technologies set a minimum average bitrate of 12Mbps for sports content, 8.5Mbps for films and 10.5Mbps for everything else (roughly 3Mbps lower than for the first generation, showing how quickly these things progress). Meanwhile some research ATEME undertook over the summer suggested that 4k transmission can be achieved in 13Mbps.
In other words, HEVC is teetering on the edge of making 4k delivery to the home very achievable. Work on ratifying the Final Draft spec is expected to be very speedy indeed.