Broadcast & Distribution News arrived today in the Display Daily work zone of a development in professional video players (as we’re spread over around 8.5K kilometres, we can’t really talk about an office!). Zaxtar of the US, based in Silicon Valley and with an office in Japan, announced that it is able to support UltraHD content at a full 60P frame rate (3840 x 2160P60), even in high quality 4:4:4 mode.
The system supports DisplayPort (and multi-output DVI) to transmit that data to the display but has also been adapted with an extra processor to allow output of 60P content on HDMI 1.4 hardware, using the option to support 4:2:0 chroma sub-sampling that is outlined in HDMI 2.0*. This means that the system can work with high quality professional systems (in 3G SDI as well), but can simultaneously drive lower cost consumer TVs.
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Zaxel has 4K and 8K servers that can support 60P
The company also has experience of developing very high end output systems including JVC’s Super Hi-vision (what some are calling 8K) DLA projectors. I would strongly recommend taking the chance to see the NHK demos at IBC or NAB, as they are very, very impressive. Zaxtar told us that its server is available from $16,000, depending on configuration.
HDMI 2.0
HDMI 2.0 is an intriguing specification. Unlike some other specifications, the features that make up each version of HDMI are all optional. It’s not hard to find forums with heated arguments that if you don’t support all the maximum possibilities of the new version (for example 10 or 12 bit colour), then you’re not truly V2.0, but that is to misunderstand HDMI.
Since the start of the specification, many features have been optional. As a result, there is really no "HDMI 2.0 product" (and HDMI doesn’t allow HDMI 2.0 as a product label). However, there are products that support features of HDMI 2.0. Consumers cannot rely on a label to identify a product that has all the features and support that they might want and need.
For example, when "Deep color" was introduced with HDMI V1.3, some unlucky, or insufficiently diligent consumers, found themselves with content sources, receivers and displays all with HDMI 1.3. However, if the receiver didn’t support and pass Deep Color data through, it couldn’t be seen.
At IFA last year, there was some controversy when Sony said that some of its existing TVs, fitted with HDMI V1.4 hardware, could be "upgraded" to UltraHD support with HDMI V2.0, by taking advantage of the provision in V2.0 of support of 4:2:0 sub-sampling. Some commentators were outraged that 4:2:0 "lossy" processing could be allowed (although the reality is that pretty well any video outside a professional studio, from a DVD, broadcast or Blu-ray is already 4:2:0).
Lossy Display Interfaces
Part of the reason for the controversy, in my view, is that up to now, most digital display interfaces were lossless. The 4:2:0 video is likely to be "visually lossless", in other words, with video content the viewer won’t see the difference, but nevertheless, the data at the display will be different from what was coming from the source.
HDMI 2.0 in 4:2:0 is not the only "lossy" display interface. In April, VESA announced the Display Stream "visually lossless" standard which will allow the compression of display data and should allow existing hardware interfaces to support the UltraHD and Super Hi-vision. As we go forward, more and more display interfaces may be "lossy".
Bob Raikes
* This is not the place for a seminar on chroma sub-sampling, which is covered at some length and with other good references in Wikipedia. Briefly; the technique exploits the fact that they human eye has less colour sensors than brightness sensors. By sampling the colour data, the overall bandwidth can be reduced.
Go to Wikipedia to check out what sub-sampling means.[/caption]
