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Switching From 1080 to Ultra HD

Radio538 (RTV) Group, the largest commercial media group in the Netherlands, has developed a new radio and television broadcast facility around a Blackmagic Design infrastructure, including the Universal Videohub and ATEM Production Switchers.
JOHNSTON, IOWA —Every now and then, the stars align and a plan comes together and for me, this article is one of those moments. Over the last few months I have been researching production switchers. Not that Iowa Public Television is looking to replace our Grass Valley Kalypso HD switcher in the near term, but I am looking into the future and what role ultra high definition will play in our operation. IPTV began shooting and editing in high definition in 1998 and we built our entire facility as a 1080i HD plant. However, even as we were building the infrastructure we were talking about 1080p as a potential step in our digital evolution. I don’t think any of us really envisioned how quickly the technology would change, but now with 4k displays already showing up in viewers’ living rooms and ATSC 3.0, the step from 1080i to 1080p may be incrementally too small to be worthwhile.

Since the research on this is essentially just that, I decided to check the offerings from Blackmagic Design. A couple of years ago I stopped by their booth at the NAB Show where they introduced their 4k production camera at an extraordinarily low price and was surprised at the quality. I thought at that time that this would be an affordable way to experiment with 4k production.

I recently started seeing advertisements for their ATEM Production Studio 4k switcher and like their camera, the price for the unit is surprisingly low. According to their website, the top of the line model is $2,495 and is self-contained in that it includes a 1 M/E 10 input switcher, DVE, graphics and keying and a multiview monitor driver. Literally you can put this in a small travel case to take to a live remote with relative ease. The price doesn’t include the control panel that we are used to so control is either by the button matrix on the front panel of the switcher frame or via software on an attached PC. I know the PC control may sound clunky but I harken back to an article I did a while back regarding touchscreen control and I would expect that the software package running on a touchscreen device would provide a much better interface than trying to use a mouse or touch pad. Of course you can order more traditional control panels for the ATEM frame.

Now before anyone runs out and buys a system, remember I started this article out mentioning stars aligning. As part of my research, I attended the SMPTE 2013 Symposium on Next Generation Imaging Formats in Hollywood last month, where most of the program was focused on UHD and there was a lot to learn. Starting with nomenclature, you may have noticed that I have used the term 4k in lower case. That is because the capital K that is so popular is actually either the symbol for potassium or specifying that a temperature is in degrees Kelvin so 4K is -452.47°F and that is cold even by Iowa standards. Furthermore, 4k is the Digital Cinema Format which is 4,096 x 2,160 pixels and UHD-1, the format we are most interested in is 3,840 x 2,160 pixels. Now this may sound like nitpicking but I invite you to engage in a discussion with IT experts on file size, storage size and bandwidth based on what a megabyte really is and it gets really confusing.

However, before making the plunge into 4k production, it is important to note that the higher resolution is not the only factor and in many cases, it may not even be the most important or critical from the point of the consumer. The importance of resolution is directly related to viewing distance and saturating the retina of the viewer. Viewing from too great a distance and the advantage of the increased pixel count is lost; too close and our eyes begin to differentiate the pixels themselves.

The optimum viewing distance for a standard HDTV set is three times picture height so for a typical 42-inch diagonal set, that is about five feet back. For a 42-inch diagonal 4k display with its increased pixel count, the distance is halved in order for the viewer to perceive the increased resolution. The viewer therefore must either view from a distance of 2.5 feet or stay at five feet and increase the size of the set to approximately 75-inches diagonally. Now while all this math is pretty straightforward and easy to do, the fact is there are very few places that have their current HD sets at the proper viewing distance and if they purchase a 4k set, there is very little likelihood that they will see any significant advantage based on resolution.

Where the benefit will come from is not just from the increased number of pixels in the raster because it is reliant on the viewing distance. Where the real “bang for the buck” will come from are the other factors whose impact is apparent to the viewer at more typical viewing distances, greater than the existing three times picture height. Factors like increased frame rates of 100Hz or higher are easily discernible at more than three times picture height. Higher dynamic range also adds to the realism of the images at more typical viewing distances; so will a wider color gamut. These elements probably have more potential for impact on viewers than resolution in most environments. However, they don’t come without a price and that price is bandwidth so even my facility with its 3 Gbps infrastructure isn’t enough.

Based on our past experience, much of the content that we create at IPTV has historical value and is considered “long-tail” content. It is therefore incumbent upon us to consider what the content will look and sound like when it is played back in the future. This means looking not only at how it is stored and archived but how much information is actually captured and preserved. Our team designed our facility to work with uncompressed in both the video and audio domains because we determined the cost penalty for going uncompressed provided a better long-term product compared to compressed and concatenated material. In the present, the technology to create an uncompressed environment is either not available or the cost penalty is too great, which is why this is still a “research project.”

So circling back to my original research on the Blackmagic Design ATEM system, when I look at the specification I noted that the UHD 4k standards support is limited to 23.98p, 24p, 25p and 29.97p which is a bit of a concern if I am looking to make content that is both future proof and will eventually provide our viewers with a significant improvement in their experience at home. Color precision on the ATEM is 10-bit which is acceptable for HD content but with 4k, the industry experts and the math points to 12 bit or 14 bit as the target. However, the spec sheet does note that the ATEM will work in the REC 2020 color space which will provide some serious benefits right out of the box.

So summing it all up, based on what I have read and the conversations that I have had, I would look at the ATEM as an entry-level product for an organization to gain some experience working in the 4k environment but it will need to gain some horsepower to handle higher frame rate and higher dynamic range to be a long-term contender. I think they are planning for that because I noticed that they talk about supporting the 6G-SDI UHD SDI Interface which, when I checked the SMPTE website, is being worked on by the 32NF- 70 work group and is 5 percent finished with an estimated completion date of mid 2015.

Bill Hayes is the director of engineering for Iowa Public Television and can be reached via TV Technology.

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