If all HDMI cables are basically the same design, pinout, etc. how have they been able to double, quadruple, etc. the bandwidth on them over time?

Question

Going from HDMI 1.4 to 2.1 there is a 5x increase is bandwidth. Is it because the cables themselves were never the issue but it was the connectors/chips in the devices themselves that couldn’t handle it?

I know part of it is the actual quality of the cables themselves and tighter tolerances, more twists in the wires, material purity, etc. but I can’t imagine that alone would be enough to fully account for this.

In: 565

Answer 1

The HDMI specification defines the pinout of the connector. There are multiple datalines that are defined.

Older specifications didn’t use all these datalines for communication and these are not necessarily connected when using an older specification cable.

Newer HDMI specification do use these additional datalines and hence more bandwidth is available for the video signal.