HDMI 2.0’s Dirty Little Secret

How much bandwidth is enough for the upcoming HDMI 2.0 standard? Well, if all you want to do is watch what you’re watching today, your current cable will work. Even if you want to watch 4K material, the standard developing HDMI Forum says you don't have to get new cable provided your cable meets the latest HDMI 1.4 spec. Step in Noel Lee of Monster Cable who is worried about future requirements for 8K and beyond. Monster announced their new cable will be capable of 31.5 Gbps, well over the 18 Gbps the HDMI forum says is required for 60 fps, 4K material. Nothing available yet, just the promise, but I’d believe the head Monster. Or else!

lostintransocean's picture

HDMI is only useful for short distances. The reason is the physical sciences. It will be interesting to see how HDMI 2.0 implements 4K as 1080p is already troublesome over longer distances.

The maths: An Ultra HD signal at 60fps provides a pixel clock of 530.8MHz (4096*2160*60). When you take this same resolution and digitize it you’re looking at a data rate of 15.93Gbps (3 colors * 10 bits * 530.8MHz). This correlates to 2.65GHz of bandwidth (pixel clock * (10 bits/2 bit cycle)). A standard Category 6 cable is specified at 200MHz bandwidth with a common rating of 550MHz which provides 1Gbps providing there is no packet loss. Video does not accept packet loss. This means the Ultra HD video is at best 5 times the bandwidth of a standard twisted pair cable. You can pretty much guarantee longer runs will not work on anything but fiber optic cables.