126 127TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 07-08/2013 — www.TELE-audiovisio...
128 129TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 07-08/2013 — www.TELE-audiov...
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  1. 1. ■ 126 127TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 07-08/2013 — www.TELE-audiovision.com www.TELE-audiovision.com — 07-08/2013 — TELE-audiovision International — 全球发行量最大的数字电视杂志 The New HEVC/H.265 Standard • reduced bandwidth by 50% • can be used also for very small screens • divides the video in 64x64 pixel blocks • requires advanced processors in the receiver Picture from Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/File:Sunspot_TRACE.jpeg (Photo Credit: NASA/TRACE) FEATURE Ultra High Definition
  2. 2. ■ ■ ■ 128 129TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 07-08/2013 — www.TELE-audiovision.com www.TELE-audiovision.com — 07-08/2013 — TELE-audiovision International — 全球发行量最大的数字电视杂志 FEATURE Ultra High Definition Designed for Ultra High Definition TV Jacek Pawlowski rate reduction for HEVC com- pared to H.264/MPEG-4 AVC was 49.3%. So very, very close to the initial target. But what about UHD? Has anybody tested the HEVC performance for higher reso- lutions than today’s HDTV? Yes, they have. One of the most rigorous tests was car- ried out by the researchers from the Ecole Polytech- nique Federale de Lausanne in Lausanne, Switzerland. They used a large ultra high resolution LCD monitor (56” Sony Trimaster SRM-L560) and prepared 3 different bit streams with different con- tent: Road Traffic, People On the Street and Sintel2 (com- puter animation). Eeach vid- eo stream was compressed with: MPEG-4 codec and HVEC codec. The test result was: HVEC significantly out- performs MPEG-4. Moreover, it is possible to achieve a 50-75% reduction in bit rate if HVEC is used instead of MPEG-4. New standard will inevi- tably entail a lot of turmoil not only in the digital TV in- dustry. It will also affect the Internet world. Most likely it will marginalize the VP8 codec that Google realized for royalty-free use. It will also affect mobile devices. Despite the fact that HVEC is specified to resolutions as high as 8,192 × 4,320 pixels, it has a lot of much lower modes of operation (the professionals call them profiles). For example, the lowest Profile 1 is specified for a resolution of 128×96 @ 33.7 frames per second and just 128 kbps bit rate. The profiles go up to Profile 6.2 which is suitable for the highest resolutions and the highest bit rates. Once HVEC is widely accepted, we will find it everywhere: from very simple cheap devices with very small screens up to the largest flat screen monitors and TVs. Should HEVC be useful only for very high res- olutions, one could be skepti- TELE-audiovision's editor Jacek Pawlowski enjoys the help of his personal assistant while working on this report. Picture 1: David Hathaway, NASA Marshall Space Flight Center (http://solarscience.msfc.nasa.gov) Table 1: Comparing Standard Definition, High Definition and Ultra High Definition Characteristics Every 9-11 years we ob- serve a step forward in digi- tal video technology. Com- pare the dates of the main standard publications: - 1992: VCD, CDi - 1994: MPEG-2 (H.262) and DVD-Video - 2004: MPEG-4 (H.264), Blu-ray Disc, Internet streaming, mobile video - 2013: HEVC (H.265) - the expected new standard for ultra high definition video The interesting thing is that this corresponds more or less to the 11 years long solar cycle. Every 11 years, the number of sunspots reach a maximum - see pic- ture 1. Is it possible that the smart guys working on digital video standardization are influ- enced by this natural phe- nomenon? Perhaps a high number of sunspots turns them up so much that they simply have to reduce the tension and publish a new standard? We will come back to that at the end of this ar- ticle. The new standard is self- explained by its name – HEVC means High Efficiency Video Coding. HVEC is claimed to be about 50% more efficient than MPEG-4/H.264. Let’s compare what bit rates are needed for today’s SD chan- nel, HD channel and a future Ultra HD channel depending on video compression meth- od: MPEG-2, MPEG-4 and HEVC. We put the figures in table 1. Please note that by a UHD channel we mean a video resolution of 3,840 x 2,160 pixels in a progressive mode (2160p). So, it is even a big- ger improvement than HD had over SD (760p/1080i vs. 480i/576i). As everybody can see, the improvement in data com- pression is tremendous. In fact, when work on HEVC started this was the main objective: to achieve about 50% improvement in coding efficiency without sacrificing video quality perceived by humans. And here we come to a very vital question: does HEVC really guarantee a vid- eo quality comparable with today’s HD? The first tests have been already carried out. Most of them dealt with HD material and indeed proved that HVEC did pretty well in comparison to MPEG-4. The final conclu- sion was that the average bit cal about its quick implemen- tation in real world products. But because it offers a 50% bit rate reduction which means also a 50% bandwidth reduction, one can be certain it will not be long when most of the new equipment will be HEVC compatible. How was it possible that HVEC is so much better than MPEG-4 which up to now we all used to regard as state of the art technology? And why did the scientists and engi- neers not invent HVEC ten years ago when they came up with MPEG-4? The answer is: 10 years ago the available processors and memories were too weak and too small to make this technology feasible. To re- duce the required bit rate by half, an HVEC receiver has to be equipped with a fast mul- ti-core processor and large and fast memories. An HEVC decoder has to process the signal in a number of tasks in parallel. This is possible because in the HEVC con- cept, the video frames are divided into multiple tiles and each tile is then processed in parallel. Moreover, HVEC breaks video frames not into 16x16 pixel blocks like it was in H.264, but into blocks of 64x64 pixels. One can easily imagine that the power of the receiver processor must be correspondingly greater to process bigger blocks. We said that HEVC is pos- sible today due to great ad- vances in technology. Let’s compare what was avail- able at the time digital video standards were and will be published: - 1992: IC technology > 1 micron, memory >50$/MB, processor 500 MHz - 2003: IC technology < 0.1 micron, memory <50$/GB, processor ~3 GHz single-core - 2013: IC technology 14 nm, memory <5$/GB, pro- cessor ~3 GHz multi-core So, were the authors of digital video standards in- fluenced by the solar cycle or rather by advances in technology? I think the an- swer is now clear. And is the HEVC/H.265 the end of the road or they will invent and standardize yet another more efficient compression stand- ard in the future? Ask me in 11 years. MPEG-2 (H.262) MPEG-4 (H.264) HVEC (H.265) SD (480i/576i) 2.5-3.5 Mbps 1.5-2.5 Mbps 0.8-1.5 Mbps HD (1080i) 12-18 Mbps 6-9 Mbps 3-4.5 Mbps UHD (2160p) 12-18 Mbps 6-9 Mbps