Does length affect HDMI picture quality?

DeadlyPilot · May 22, 2016

I need a rather long HDMI cable to go through the wall from my PC to my TV. I've done endless research on weather or not length affects the picture quality, and so many sources seem to contradict each other as of no one knows what they are talking about. So many people say that all cables are the same but others will say that theres a difference between a high speed rating and a standard rating which only supoorts 1080i. Also, would a longer cable cause latency? I will be using this for gaming so I need to know if a shorter length will give me an optimal signal.

Godlygamer23 · May 22, 2016

It won't affect picture quality because it's digital. But make sure the HDMI cable can actually work at the specified length as eventually you will encounter drop-off where the signal is not strong enough anymore.

HDMI cables are mostly all the same as far as the function is concerned. It is a standardized port, but that doesn't mean all manufacturers follow the minimum requirements.

Glenwing · May 22, 2016

For practical purposes, there is only one type of HDMI cable, called a "High-Speed HDMI Cable", or a Category 2 cable. There are no other types of HDMI cables in the real world. The only people who say there are multiple types are just people reading wikipedia descriptions of the standard. The HDMI standard does define a specification for a "category 1" cable which is only rated for 720p/1080i 60 Hz or 1080p 30 Hz, but no one actually produces category 1 cables, they don't exist in the real world.

Even if they did, it would have no effect on image quality. Cables in modern digital standards have zero effect on image quality. The only thing they determine is the maximum data rate, which dictates the maximum resolution and frequency, though even that is rarely limited by the cable itself. Signals do degrade the longer the wire is, but this won't reduce image quality. If the signal degrades below the point where the monitor can interpret it, the image will drop out. You either get everything, or you get nothing. There is no in-between image quality. HDMI doesn't have a defined maximum length but it's usually considered good out to about 15 meters before you need amplifiers.

As for latency, we are talking about electrical signals here, not water flowing through a pipe. If you hook a light bulb to a battery, you aren't going to have a delay before it turns on just by using a longer wire, not on a practical scale anyway. Cables have no effect on latency no matter what standard you are using. All latency is introduced by the signal processors behind each port which encode and decode the signals, and by the display controller if it does additional image processing before rendering the image to the screen.

DeadlyPilot · May 22, 2016

11 minutes ago, Glenwing said:

For practical purposes, there is only one type of HDMI cable, called a "High-Speed HDMI Cable", or a Category 2 cable. There are no other types of HDMI cables in the real world. The only people who say there are multiple types are just people reading wikipedia descriptions of the standard. The HDMI standard does define a specification for a "category 1" cable which is only rated for 720p/1080i 60 Hz or 1080p 30 Hz, but no one actually produces category 1 cables, they don't exist in the real world.

Even if they did, it would have no effect on image quality. Cables in modern digital standards have zero effect on image quality. The only thing they determine is the maximum data rate, which dictates the maximum resolution and frequency, though even that is rarely limited by the cable itself. Signals do degrade the longer the wire is, but this won't reduce image quality. If the signal degrades below the point where the monitor can interpret it, the image will drop out. You either get everything, or you get nothing. There is no in-between image quality. HDMI doesn't have a defined maximum length but it's usually considered good out to about 15 meters before you need amplifiers.

As for latency, we are talking about electrical signals here, not water flowing through a pipe. If you hook a light bulb to a battery, you aren't going to have a delay before it turns on just by using a longer wire, not on a practical scale anyway. Cables have no effect on latency no matter what standard you are using. All latency is introduced by the signal processors behind each port which encode and decode the signals, and by the display controller if it does additional image processing before rendering the image to the screen.

Thank you! This was very descriptive. I'll probably go with the longest cable I can get to make things easy