Last month, I talked about shooting in 4K or UHD, but does “4 times full HD” make any sense elsewhere in the deliverables chain? I suggested that the UHD shooting decision should be driven by what most viewers actually see, and I noted that it might make sense to put more bits into dynamic range or improved color, instead of more resolution. We should also ask if our delivery systems can handle any more bits. The answers will differ for each delivery system. Most of us already have limitations placed on our viewing by streaming bandwidth limits, marginal cable performance and interference in over-the-air signals. Trying to cram more bits through the paths from camera to display will further stretch those limitations and eventually break the system at the weakest links. The results may be longer download or buffer times, breakup in the middle of a program (really fun if you’re trying to watch a ball game) or video freeze-frames and/or audio dropouts every few minutes (annoying, even if you don’t miss much content).
Each type of delivery medium has its own performance strengths and weaknesses, in addition to its costs and conveniences. How those match up with individual viewer preferences will affect our selections between the multiple content sources now competing for our attention. Most of us have a favorite viewing area, be it a TV set in the living room or family room, or a “tricked-out” dedicated viewing room, with big screen and surround sound, and equipped for viewing whatever media is available via the delivery system “du jour.”
Home viewing areas define the places where the signal meets the viewer, where the digits become analog again, where audio and video become sound and image. Today’s home theater needs options for several different deliverables. I just installed a new receiver that can pass several UHD or HD signals through to my video display. One could come from an Ultra Blu-ray (UHD) or a standard Blu-ray player (HD), another from my cable box (also limited to HD) and another from a streaming server. The server video might be HD, UHD (3840×2160) or full 4K (4096×2160), but the time necessary to download a higher-resolution signal undoubtedly will be longer than for a corresponding HD version. It probably won’t be four times as long because different trade-offs will be made to get the bandwidth down. But that also means the picture won’t be four times as “good” as the HD. Which aspects of “good” are compromised depends on which of those trade-offs were made…and where…and by whom…and with what processors.
You may want to experience 3D programming in your system, or you may be experimenting with virtual reality or some other advanced technique that may be limited to lower resolution in its early stages. My receiver will pass those signals through, even though it doesn’t need to know anything about them; the display device needs to figure out how to handle the funny stuff. In fact, the receiver doesn’t really care about most of the content of the signals. It does need to decode audio for my surround system, and it can connect with my iPad to play back music from it. But one thing that it does need to know about is packaging and security protocols, in order to “handshake” or negotiate with the display to make sure it can legally deliver a protected signal to the display.
Myth: Your home theater—a piece of cake!
The most common example of wired security protocols is contained in the HDMI (High-Definition Multimedia Interface) connection on most modern display devices. The HDMI connection is subject to the restrictions of the HDCP (High-Bandwidth Digital Content Protection) scheme, which is designed to make sure the rights of copyright owners aren’t compromised by pirates. One side effect of this protection is that users with legitimate authority to access material are often stymied in attempts to improve the presentation of the material without spending thousands of dollars for new hardware when manufacturers upgrade the protection schemes to match the march of delivery and display technologies.
For example, you may have noticed that Blu-ray players no longer have HD component analog outputs. Those of us who grew up in the 20th century dealt with the transition from analog composite (NTSC in North America), through analog component (think Betacam format), through analog high definition (yes, there was analog HD), to digital component HD and the most common interface—SDI (Serial Digital Interface). None of those had effective copy protection schemes, but there were hardware-specific attempts that usually degraded the video, although back then, most hardware degraded the video. Today’s digital systems are almost transparent, compared to analog ones…but I digress.
HDMI is the consumer development of wired digital HD distribution technology, so a lot of effort was invested in keeping those high-quality program streams from being diverted to easily replicated mass-media packages that would divert mass quantities of income from the original producers and distribution companies. Breaking down digital HD signals to analog component made copying a little too easy for the corporate lawyers, hence HDCP. Cable interface boxes, Blu-ray players, media servers, home computers, cameras, video games, direct-view displays and projectors all use HDMI, so any home theater video controller or router needs to play nicely (and legally) with HDMI and HDCP protocols.
One of the most annoying “features” of HDMI/HDCP connections is that every time you switch between deliverables (for example, pausing a Blu-ray or streaming movie to check on the score of the game you’d rather be watching), the devices need to renegotiate the protection agreement, call in a couple of lawyers, make sure your request is legal, then make the new connection (and, of course, repeat the process on the way back to the movie). Obviously, I’m exaggerating, but only in the process; the frustration is quite real.
Another issue is the difficulty of driving multiple displays from one HDMI source. You can buy splitters, but if the display devices aren’t identical (and even sometimes when they are), you can experience hair-pulling frustration getting them all to display anything. With the advent of 4K or UHD signals, HDCP 2.2 was introduced, and many older devices aren’t able to negotiate that protocol. You’ll still be able to use your older sources with newer displays, and possibly pass through new sources, but you won’t be able to take advantage of all the new features without upgrading your receiver or other processors. Sometimes, a software update is required; otherwise, get out your wallet again because it will cost you.
Home theaters can be described much like houses and boats; they’re money pits that continually help you reduce your retirement nest egg—but they can be lots of fun for techies. In future columns, I’ll try to expand on the trials and tribulations of optimizing viewing quality as the tornado of technological advance swirls around your system.
So much “mis-information,” so little time….
C.R. Caillouet is a technical producer and video engineer who has worked in TV production, from preproduction through field acquisition to postproduction and presentation, as well as for NASA, Sony and Panasonic. He’s currently Technical Director of the Jackson Hole Wildlife Film Festival and Science Media Symposium.
Decoding Deliverables — Areas of Degradation Along the Image Chain
Cable — Just because you are connected through a wire doesn’t mean that you can’t suffer dropouts. Weak digital signals translate into dropped frames and or missing audio instead of the noisy signals that we grew accustomed to in the analog video age. At least you could often make out the signal as it degraded.
Satellite — rain fades
Internet file delivery – network loading, wi-fi capacity limits
Internet program streaming – continual improvements
Blu-Ray/DVD playback – dirty discs, poor mastering
Over-the-air broadcast – blockages, grade contours, disparate antenna locations
Mobile device origination – screen size, Gx data rate limits, handoffs, OS limits (no flash or lights – heightened noise from ISO performance)
Insecure transient signals, Wi-Fi and Bluetooth interfaces
Conversion cadences and artifacts from frame rate conversions, spatial conversions and codec conversions
Transmission tradeoffs – Luma, chroma and frame rate sub-sampling
Data rates within each codec decision — lossy compression with h.264, h.265, HAVC, HEVC and WMV
Processing and display devices — Number of bits, sampling rate, re-sampling equalization and auto-setups
Screen sizes and mobile device integration — Screen sizes affect viewer perceptions of image quality and often determine how much image quality drives upgrade decisions