Is It Snappy? Application that takes a movie with iPhone camera and measures delay time "latency" of every computer

The delay time until the instruction is sent to the device and the result is returned is "LatencyIt is called. The smaller the latency is, the more reactive it is comfortable, but if the latency is large, it will appear as bad response and will significantly impair the user experience. An application that easily measures the latency related to such sensible speed using the iPhone "Is It Snappy?"Has appeared.

Is It Snappy?
http://isitsnappy.com/

Chad Austin who works as a technician at Dropbox explains about "latency" unexpectedly known and how to measure latency.

What is latency?
Latency with opportunities to see in discussions such as "Which text editor is the most responsive?" Is one indicator of computer responsiveness. For example, in real-world actions such as picking objects and writing letters on paper, there is no time lag between "input" and "response", latency naturally is zero. However, in the world of computers, there is a process of processing and outputting inputs, so latency exists even at a level that can not be experienced.

Surprisingly, with the evolution of computers and technologies, latency has increased and the speed of bodily sensation is getting worse. "If you have a chance, try operating Windows 95 with an old PC, you should be surprisedly responsive," Austin said. Actually, as the technology advances, the computing speed of the computer has increased, but at the same time, the complexity of the hardware and the program is increasing, and as a result, the latency seems to be larger than it was in the past.

In addition to that, as a result of the concept of latency becoming known, "The person sensitive to latency" also increased, it is also caused. Latency is likely to increase due to equipment that is more complicated than in the past, latency sensitive users are increasing, and latency becomes more problematic.

◆ Is It Snappy?
Such latency is said to be easy to measure by just shooting a movie with the iOS application "Is It Snappy?" Made by Austin. The iPhone has a "slow motion" shooting function after iPhone 5s and you can shoot at 240 fps if you are an iPhone after iPhone 6, that is 240 frames per second. "Is It Snappy?" Is an application to measure the latency by shooting movies at a high frame rate using the slow motion function and counting the reaction delay from the number of frames.

The following is an example of measuring the latency of DELL's 2007 FP liquid crystal display using NES Classic (Nintendo Classic Mini)'s Super Mario Brothers. In addition, NES is selected as an excellent terminal that can ignore latency with a simple structure.


Start shooting with the camera of Is It Snappy ?.


Push the controller to jump Mario.


Stop recording if you can shoot a movie to jump.


A 240 fps movie taken with "Is It Snappy?". The number of frames is displayed at the bottom of the screen.


Set the frame at the moment you pressed the button to the starting position ... ....


I felt it was "after 21 frames" if Mario fast forwarded the movie to the position where he began to jump by reacting to the picture. In other words, since there is a delay of 21 frames at 240 fps (per frame), the latency can be measured as 1 s ÷ 240 x 21 = 87.5 ms.


The measurement result can be saved with a name.


Austin who measured the latency of various terminals using 'Is It Snappy?' Which can easily measure latency reports that interesting results were obtained.

First of all, in the test using NES Classic, the latency of the Samsung LN 46 C 650 used as a television is about 170 ms, which is twice that of DELL's liquid crystal display. The keyboard of the MacBook Pro made in 2015 said that latency was 40 ms longer than why the wireless keyboard was connected for some reason. Also, the latency of the text editor states that Ubuntu is better overall than Windows 10.


I tried using "Is It Snappy?"
"Is It Snappy?" Which can measure the latency with the slow motion function of the iPhone camera can be downloaded for free in the App Store.

Is It Snappy? On the App Store
https://itunes.apple.com/us/app/is-it-snappy/id1219667593

Search "Is It Snappy?" On the App Store and tap "Get".


Tap "Install".


Tap "Open" and activate "Is It Snappy?".


Since you are asked for permission to access photos, tap "OK".


Tap "Camera" icon.


Since you are asked for permission to access the camera, tap "OK".


Since the camera starts up, you can tap "Record" in the bottom right and shoot the movie. Using Power Point 2007, try measuring the latency of letter input of Let's Note CF-SX2.


Swiping the screen left or right makes it possible to feed a movie one frame at a time.


Select the frame at the moment when you press the keyboard, tap "Mark Input" at the bottom left, and register it in the initial frame. OK within () in the frame number in the center lower is "0" OK.


Next, select the frame at the moment the character appears on the screen, tap "Mark Output" at the bottom right.


Since it is 10 frames after the initial frame, latency was measured as 41.7 ms.


After that, it is OK if you save the data with a name.