[转帖] [Technology Monitor] [2013.03.09] After 3D, here comes 4K 3D之后，4K来临

showcraft

http://bbs.ecocn.org/thread-181238-1-1.html
Difference engine
另一消费引擎

After 3D, here comes 4K
3D之后，4K来临


Home entertainment: A new television standard called Ultra HD is four times sharper than today’s best HDTVs. But providing content in this new format poses daunting technical challenges. And does anyone really need it anyway?

家庭娱乐：比今日最好的高清电视还要清晰4倍的超高清电视标准已经出现。但是为这种新格式提供内容还要遇到技术挑战，同时是不是大家都真正需要它呢？

HAVING seen interest in 3D television fizzle, electronics firms are eager to find another blockbuster product that will get consumers to splash out. The development most are hoping will do the trick is a display technology known as Ultra High-Definition, which offers four times the resolution of today’s most advanced “1080p” HDTV sets. No question, Ultra HD provides stunning images—at least when displaying content created in the new “4K” video format. Unfortunately, only a handful of feature films (including “The Amazing Spider-Man”, “Prometheus” and “The Hobbit”) have been shot with 4K-capable cameras.

3D技术逐渐降温，电子公司们正急切寻找另一重磅产品让消费者大出血。超高清显示技术被寄予厚望，它比现今最好画质的1080p的高清电视还要清晰四倍。毫无疑问，超高清技术至少能够在以“4K”视频技术制作的内容上显示令人惊艳的画质。遗憾的是，只有一小部分电影（像神奇蜘蛛侠，普罗米修斯，霍比特人）是以4K摄像拍摄技术而成的。

Will 4K follow 3D’s fate? It is far too early to say. But 4K television—far more than 4K cinema—faces some formidable obstacles. As with 3D television, the new 4K television format takes its lead from Hollywood. The existing wide-screen digital format used in cinemas is 1,998 pixels wide and 1,080 pixels tall. The 4K film standard has twice the resolution vertically and twice horizontally—ie, 3,996 pixels across the frame and 2,160 down—making it four times sharper all round.

是不是4K技术难逃3D技术的厄运呢？现在说还太早，4K电视技术要比4K电影遇到更加棘手的障碍。与3D电视一样，好莱坞4K电视走在最前沿。目前电影院的宽屏数字格式是1998*1080，4K电影技术标准是其垂直和水平分辨率为原来的两倍，即3996*2160，其清晰度为原来的四倍。

By contrast, the 4K format used in television is slightly narrower, having 3,840 pixels across and 2,160 pixels down. The screen width was reduced to maintain the 16:9 aspect ratio of HDTV, with its 1,920-by-1,080 pixel count. This makes it possible to show existing video content that has been “upscaled” for Ultra HD without the need for black “letterbox” bands above and below the picture.

相比之下，3840*2160的4K格式的电视屏幕过于窄小，屏幕得与16：9纵横比（1920*1080）的高清电视相适应。但这样可以使得超高清显示目前存在的视频更加“清晰”，而且去除了画面上下的黑边。

But who actually needs a super-sharp 4K television? The resolution of even an HDTV set with 1,080 progressively scanned lines (ie, continuously from top to bottom) is wasted on the vast majority of viewers. Most people sit too far from the screen to be able to see the detail it offers. A study done some years ago found the median eye-to-screen distance in American homes to be nine feet (2.7 metres). But researchers reckon that, given the human eye’s limited acuity, people even with 20/20 vision should sit no farther than 1.8 times the width of the screen away from it, if they are to distinguish the detail displayed.

但是谁真的需要超高清4K电视呢？甚至于高清电视的1080p逐行扫描（即从顶部持续扫描到底部）对于大多数观众来说都是浪费，而且大部分人离屏幕太远很难看清其细节，几年前的一项研究表明美国家庭人员眼睛距屏幕距离中位数为9英尺（2.7米），研究人员还发现，由于人类眼睛灵敏度的限制，如果想要看清屏幕显示的细节，即使视力正常的人距屏幕的距离也应该在屏幕宽度的1.8倍以内。

At a distance of nine feet, even an existing HDTV set would need to have a screen of around 70 inches across the diagonal for viewers to benefit from the resolution they have paid for. With anything smaller at that distance, details simply blur into one another. There is no question that, with twice the resolution horizontally and vertically, a 70-inch Ultra HD screen would be pretty impressive from nine feet away, and would still provide resolvable detail at up to twice that size.

目前大约需要70英寸的高清电视才能为距离屏幕9英尺的的观众提供与他们付费相匹配的分辨率。如果小于这个距离，细节就会变得模糊。毫无疑问的是，屏幕分辨率长宽加倍的超高清电视屏幕，在9英尺远处能够提供美轮美奂的画质效果，即使距离加倍的话，仍能够看清楚。

So the best argument for moving to Ultra HD is the trend towards larger screen sizes generally. Today’s HDTV sets begin to look spotty when their meagre 2.1m pixels are spread over screens greater than around 80 inches. With 8.3m pixels to play with, Ultra HD screens can be made twice as large before the pixels become too glaringly obvious.
所以现在关于超高清的争论一般关于越来越大的屏幕尺寸。现今的2.1百万分辨率高清电视内容在80英寸的屏幕上显示很模糊。如今有了8.3百万的分辨率的超高清屏幕，即使做得再大两倍，也不会变得很模糊。

Assuming you have the space and the budget for an 80-inch-plus TV, the next hurdle will be getting native 4K content onto its screen. In raw form, a two-and-half-hour film shot in 4K at the usual 24 frames per second contains 216,000 frames. With each frame of the film containing 8.6m pixels, and each pixel having 24 bits of colour information, the resulting video file contains 5.6 terabytes of data. Even with compression, transmitting such gigantic files over the air or by cable would require more bandwidth, at far greater infrastructural cost, than broadcasters can afford. Streaming a feature-length 4K file over the internet would run into similar bandwidth constraints. The internet connection needed would have to transport data at speeds up to a gigabit a second. Few homes have broadband that fast.

假设你有这样的空间和预算买一台这样80英寸以上的电视，下一步障碍就是把国内的4K内容搬上银幕。未经过处理的2.5个小时的4K，24帧格式的电影每秒包含216000帧画面。每一帧包含8.6百万像素，每个像素包含24字节色彩信息，最终的电影将达到5.6T字节的数据量。即使经过压缩，通过有线或无线传输这样的大文件就要求更高的带宽，这样的基础设施成本不是电视台所能承受的了的。在网上缓冲4K文件也有相似的带宽限制，而且连接传输速度达到1G/s，很少有家庭能达到这样的速度。

An alternative would be to distribute 4K films as Blu-ray discs, just as conventional 2K films are sold—or were until people switched to streaming them instead from Netflix, YouTube, iTunes and other online services. A 2K film etched on a Blu-ray disc uses all 50 gigabytes of its two recording layers. A 4K film would require a third or fourth layer. Even then, a more efficient compression method than the current H.264 standard would be needed to shoehorn a 4K film onto a Blu-ray disc.

另一可选择方案就是把4K电影以传统2K电影发行方式——蓝光碟形式发售，或者人们从Netflix, YouTube, iTunes等网上服务公司缓冲观看。刻入蓝光碟的2K电影需要两个记录层的全部50G，4K电影只需1/3或1/4层，即使这样，目前还是需要一个比H.264 标准的更加有效的压缩方法来将4K电影塞进蓝光碟片中。

Get ready for a squeeze
为压缩做准备

So a new compression standard is evidently required. How “lossy” could a compression method afford to be before it compromised the quality of a 4K picture? The international bodies responsible for compression standards have been discussing a successor to H.264 for the best part of a decade. The latest draft, known as High Efficiency Video Coding, is said to double H.264’s compression ratio without loss of image quality. Even if that proves up to the job, it will take years for the new compression standard (H.265) to be adopted universally. Many in the industry feel that if 4K television is to succeed, an entirely new way of encoding and delivering its content is needed.

目前最需要显然是一个新的压缩标准。在保证了4K画质的同时，多大的“压缩损失”才符合要求呢？国际压缩标准机构一直在讨论H.264标准之后的下一个10年技术标准，最新的方案是H.265，在没有损失画质的情况下，其压缩率是H.264的两倍。即使该标准得以实行，但也需要几年才能普及。许多生产商认为4K电视是未来的方向，目前需要全新的方法来进行编码和传送。

Sony’s answer is to bundle a media server with its first generation of Ultra HD television sets. The server will come with ten films preloaded on its array of hard drives, along with a selection of short videos. Sony says the films included are direct copies of pristine 4K masters. But no one has said how customers will add fresh titles to their servers. This is obviously a stopgap measure, designed to encourage wealthy early-adopters to splash out on the latest video fad. (Sony’s 84-inch Ultra HD set costs $25,000, and buyers are also given a media server on loan.) But if Ultra HD is to be HDTV’s successor, then sooner or later cable and satellite-TV providers and streaming-video services will have to find a way to deliver 4K content reliably and cheaply. No doubt, they eventually will. The question is when.

索尼采取的措施是将视频服务器和第一代超高清电视捆绑销售。服务器将在其硬盘上预装10部全新的原装4K电影和一些精选短片。但并未说明消费者怎样将电影添加至服务器，显然这只是一个过渡措施，其设计目的是让富人在最前沿的视频服务上花钱（索尼的84英寸的超高清电视售价25000美元，同时消费者获得媒体服务器租赁）。如果超高清电视成为高清电视的替代者，毫无疑问的是，卫星电视和视频服务提供商最终迟早会找到一种可靠而又廉价的方式来传送4K内容。关键是他们什么时候找到。

The best guide is the penetration of HDTV. America’s first nationwide broadcast in digital high-definition was John Glenn’s lift-off in the space shuttle Discoveryin 1998. It took another dozen years for HDTV to go mainstream. By that reckoning, it is likely to be 2025 before Ultra HD is in half of all American homes.

高清电视的逐渐流行就是很好的指引。美国第一次数字高清播放的就是1998年发现号宇宙飞船的John Glenn起飞场景。这使得高清电视花了12年成为主流，照此计算，美国一半家庭装上超高清电视估计要到2025年。

From the print edition: Technology Quarterly

showcraft

没有细看。
这个概念，似乎游资要炒，还是有难度，首先比较小众高端，市场需求不会太大，其次国内相关产业较弱，可能港股的创维还行。