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Everywhere we turn to lately in the Pro AV space has a "4K" or "UHD" badge stuck to it.  Some even say "4K ready."  Unlike the 3D buzz several years ago, it would appear that 4K is here to stay.  In today's current state of hardware and cables, there are a few things to understand when designing and deploying these Ultra High Resolution solutions.  Before we get into some design considerations, let's first clarify a few facts.

3840x2160, commonly referred to as Ultra HD or "UHD," is exactly four times the resolution of 1080p (1920x1080).  This resolution has the same aspect ratio of 1080p HD, or 16:9.

4096x2160, commonly referred to as 4K, is primarily used in the film and broadcast industry and has a native resolution of 4096x2160.

Very few sources beyond computers are outputting these resolutions due to bandwidth limitations

 

Now, let's dig into some of the design challenges-

When transmitting 1920x1080 video at 60fps, a data rate of 4.46 Gbps required.  To deliver 4K resolution, you would increased the required data rate by a factor of four.  Currently, the highest rated HDMI cable is the 2.0 standard, supporting 18 Gbps.  This is obviously a considerable jump in data that hardware pieces must also handle.

Color Space is another consideration that must be managed.  HDMI 2.0 includes support of BT.2020 colorimetry with 10-bit color depth or higher. Color depth can be produced in 8, 10, 12, and 16 bit rates.

The frame rate speed of video effects the color sampling rate we can use.  Basically, if you want to run video at 60Hz, you must run a reduced color sampling rate.  If you choose to use a 16-Bit sample rate, you must reduce your frame rate.

 

What does all this mean?  Well, in our opinion, HDMI 2.0 has some limitations to providing the full 4K spectrum.  If you want full frame rate- reduce your color space.  If you want full color space- reduce your frame rate.  If you want full color space and frame rate- reduce your resolution.

Fortunately, we are in the technology market and our industry continues to rapidly evolve due to tremendous innovation.  The current DisplayPort 1.3 standard, can support bandwidths north of 30 Gbps.  If sacrificing video quality is not an option, a direct cable run from a source over DisplayPort 1.3 cabling can deliver the content.  It is now just a matter of time before the industry transport giants build their connection platform on a DisplayPort 1.3 standard and migrate away from the HDMI 2.0 platform.

If you wish to take your system into the 4K realm, make sure you understand, or your AV Partner understands the challenges of dealing with this signal.