New standard HEVC encodes films more efficiently
Television resolution is constantly improving – and this must go hand-in-hand with transmitting the data more efficiently. Reputable manufacturers of televisions, computers and mobile telephones, working jointly with Fraunhofer researchers, are developing a new standard for data transmission: “High Efficiency Video Coding”, or HEVC for short. This video codec will be unveiled in Amsterdam at the IBC trade show, from September 7 - 11, 2012 (Hall 8, Booth B80).
The opening ceremonies for the Olympic Games captivated countless viewers all over the world in front of their televisions, astounding them with a gigantic show. Relatively few people were able to have a live experience of the spectacle at the London stadium. Still, some of the fans watching the show felt as if they were there live, even though they were only sitting in front of a large cinema screen. That’s because a few movie theaters showed the opening ceremonies in 8K-resolution, which corresponds to 33 megapixels.
The resolution on home televisions will soon be enhanced even further, conveying the feeling of being right in the middle of the action, instead of just watching from the sidelines. Indeed, the successor to the full HD television set is already penetrating the market: the 4K display, also called 2160p format. These televisions have four times as many pixels as the TVs in our living rooms today. Still, the continuously growing number of pixels must also be fed with the matching content, so that the capabilities of the high resolution television can also be utilized. But to do so has always been tied to immense costs, until recently, and therefore was only considered for major events, like the Olympic Games.
The previous standard for encoding data and sending it from the broadcaster to the home television set is known as H.264/MPEG-4 AVC. Theoretically, it has certainly been up to handling the mass of data; however practically, the broadcasting of higher resolution entails substantial costs: because an additional channel is needed for television broadcasts, and for Internet transmission, the server needs a wider bandwidth. A majority of the reputable electronics manufacturers have now joined forces to develop a new broadcasting standard together: HEVC, short for "High Efficiency Video Coding." The labs at the Fraunhofer Heinrich-Hertz-Institute HHI in Berlin, which played a critical role in the engineering of the H.264 predecessor standard, also made a substantial contribution to this new standard.
Twice as efficient as H.264
The advantage of HEVC: The standard requires half the bandwidth for high quality video transmission. But how is it being done? "Parts of H.264 were subsumed and optimized," explains Dr. Thomas Schierl, group manager of multimedia communications at HHI. "One example is the block size: whereas H.264 subdivides the transmission image into blocks of 16 by 16 pixels, HEVC instead carves the image into blocks of varying sizes with up to 64 by 64 pixels. These larger blocks can be encoded considerably more efficiently." If an object is seen in the image that moves to the side, then this movement occurs smoothly. The standards establish the movement data for each block - data that is ordinarily transmitted once per block. Because the blocks in HEVC are substantially larger than in H.264, correspondingly less movement data are needed. Compared to H.264, since the computational effort for the higher coding efficiency increases sharply to encode or decode the images, HEVC in the standard design allows computer units to work parallel with each other. Either the image is separated out into several parts, known as tiles, whereupon each processor works on one of them, or in the wave front method, where the processors each handle one block of lines in the image. These methods allow encoder manufacturers to get implementations and products to market rapidly.
The development is scheduled for completion in January 2013. Thereafter, new televisions, smartphones and PC units will presumably contain decoders that convert data – encoded with HEVC – into high-resolution television images. The HEVC standard for 3D movies should follow in one to two years. HEVC will be presented at the IBC in Amsterdam from September 7-11, 2012 in Hall 8, Booth B80. Visitors can watch a full HD film on an HD television being converted live by the HEVC decoder into high-resolution television pictures. They can change movies, pause playback, fast forward and also rewind.
Standard for video telephony and video streaming as well
The new standard will deliver benefits to video telephony as well. It too, was hitherto largely based on H.264. With HEVC, the image quality can be increased substantially at the same data rate. Likewise, the transmission can be adapted for web video-streaming. MPEG-DASH, a transport format for multimedia streaming, currently enables viewers to watch judder-free videos via the Internet. Today it allows the transport of H.264-encoded contents as well as other standards. The researchers are planning to extend DASH by April 2013 in such a manner that it can also transmit HEVC-encoded videos.