Input Lag Explained

Input Lag Overview

When trying to play a video game or use a TV as a PC monitor there is one thing they have in common. Being able to do what you want to do when you want do it. This is where a good input lag comes into play.

To illustrate this point, think of playing your favorite video game. You’re trying to walk around when you move your character to the left and they just stand still. You try again and then they move twice!

That is a input lag that is struggling to keep up with you and what you want to do. Granted this is not the case for every TV, and it also comes down to how you will perceive the input lag as well.


 input-lag-trt
What it is: A delay in an action on the screen and the actual input.
Why it matters: Smooth interaction that leads to a more immersive experience.
When it matters: Video games and using a TV as a PC monitor.

Input Lag Testing

Outside Game Mode

I first test all available resolutions outside of any ‘Game Mode’ options. this is because often times the ‘Game Mode’ options disable many of the TV’s higher end features.So, this is a good test to do so you can see how well the TV performs while keeping access to all of its features.

Though often times I find that the TV struggles far too much to really make the features worth it if you are playing video games. The testing I do here will mimic all of tests of input lag that I do.

No Motion Interpolation

I then ensure ‘Game Mode’ is off, at the same time motion interpolation features are turned on. This is because those features often times will smooth an image or scene making it easier for the eye to notice the slight delay in inputs. So, by turning on motion interpolation you can better test the results so notice any hiccups.

Though, I often find the features do not make a larger difference. This will mostly come down to your preference. The testing I do here will mimic all of tests of input lag that I do.

Input Lag with Game Mode

Just like the two prior tests I then test input lag with ‘Game Mode’ features on. I do this across all available resolutions to find what works best and what does not.

I find that ‘Game Mode’ will often make a huge difference or no difference at all. It is not often that it only makes a slight difference. The testing I do here will mimic all of tests of input lag that I do.

Input Lag Measurements 

Time. Simple as that.
A delay is time so we need to measure the time it takes for the display to produce a change that you sent to it.

A common way to do test the time difference is to connect a laptop to a monitor or TV. Then display a timer on both. When you send the input to both screen the timer starts. Then take a photo of both screens. The difference in the timing results in the photo is the input lag. This only an approximation of the input lag. Though I’d gamble that is very close. You can find a timer here.

On the other hand I was lucky enough to get my hands on a Leo Bodnar tool for testing input lag. You can find that same tool here. It works very well and is easy to use in my opinion.

Causes of Input Lag

There are there components of an input lag.
The stage where the image is grabbed or sourced.
The stage where the image is processed.
Then finally, the stage where the image is displayed.

Acquisition

The longer it takes for the TV to source the incoming image the longer the input lag will be. Different inputs will make a slight difference here. For instance a HDMI cable works best to minimize the lag. Where as component cables need to covert the analog signal into a digital signal. Which takes time. Often times modern TVs do not struggles with this part of the input lag.

Video Processing

Once the incoming image has been sourced and then converted if need be, the TV will then begin to process the image. Anything from adding a sleek overlay to the image or adjusting the frame rate. Everything that needs to be handled happens inside milliseconds of time to produce a great image or scene for you. The most common things that need done are:

  • Adding menu or overlays
  • Adjusting the colors and brightness of the incoming image
  • Adding motion interpolating the picture to match the TV’s refresh rate
  • Input Upscaling or down Scaling

Displaying The Image

This then comes full circle. Once the processors are finished they send the information to the display to produce the image or scene. The biggest away here is that the TV cannot change its LCD’s state instantly. The LCD take time to wind up or wind down. I go more in-depth to this topic here.

Best Results

Often times many manufacturers will have a ‘Game Mode’ setting or other small settings to best help with lowering the input lag. Below are some manufacturers and the settings they usually have available.

LG Menu > Picture and set ‘Picture mode’ to ‘Game
Vizio Menu > Picture > More picture and set ‘Game Low Latency’ to ‘On.
Samsung Menu > Picture adjustments and set ‘Picture mode’ to ‘Game.’
Sony Menu > System > General and set ‘Game mode’ to ‘On.’

Conclusion

An input lag is simply the measurement of time between you sending information to a display and the display producing the change on screen.
Though, an input lag can be very bad, very good, and everywhere in between I’d recommend a better one over a worse one any day. In the end it all comes down to preference.
Hope this helps iron out some of the kinks with input lag.

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