lcd panel input lag free sample
When you"re using a monitor, you want your actions to appear on the screen almost instantly, whether you"re typing, clicking through websites, or gaming. If you have high input lag, you"ll notice a delay from the time you type something on your keyboard or when you move your mouse to when it appears on the screen, and this can make the monitor almost unusable.
For gamers, low input lag is even more important because it can be the difference between winning and losing in games. A monitor"s input lag isn"t the only factor in the total amount of input lag because there"s also delay caused by your keyboard/mouse, PC, and internet connection. However, having a monitor with low input lag is one of the first steps in ensuring you get a responsive gaming experience.
Any monitor adds at least a few milliseconds of input lag, but most of the time, it"s small enough that you won"t notice it at all. There are some cases where the input lag increases so much to the point where it becomes noticeable, but that"s very rare and may not necessarily only be caused by the monitor. Your peripherals, like keyboards and mice, add more latency than the monitor, so if you notice any delay, it"s likely because of those and not your screen.
There"s no definitive amount of input lag when people will start noticing it because everyone is different. A good estimate of around 30 ms is when it starts to become noticeable, but even a delay of 20 ms can be problematic for reaction-based games. You can try this tool that adds lag to simulate the difference between high and low input lag. You can use it to estimate how much input lag bothers you, but keep in mind this tool is relative and adds lag to the latency you already have.
There are three main reasons why there"s input lag during computer use, and it isn"t just the monitor that has input lag. There"s the acquisition of the image, the processing, and finally actually displaying it.
The acquisition of the image has to do with the source and not with the monitor. The more time it takes for the monitor to receive the source image, the more input lag there"ll be. This has never really been an issue with PCs since previous analog signals were virtually instant, and current digital interfaces like DisplayPort and HDMI have next to no inherent latency. However, some devices like wireless mice or keyboards may add delay. Bluetooth connections especially add latency, so if you want the lowest latency possible in the video acquisition phase, you should use a wired mouse or keyboard or get something wireless with very low latency.
The time this step takes is affected by the speed of the video processor and the total amount of processing. Although you can"t control the processor speed, you can control how many operations it needs to do by enabling and disabling settings. Most picture settings won"t affect the input lag, and monitors rarely have any image processing, which is why the input lag on monitors tends to be lower than on TVs. One of these settings that could add delay is variable refresh rate, but most modern monitors are good enough that the lag doesn"t increase much.
Once the monitor has processed the image, it"s ready to be displayed on the screen. This is the step where the video processor sends the image to the screen. The screen can"t change its state instantly, and there"s a slight delay from when the image is done processing to when it appears on screen. Our input lag measurements consider when the image first appears on the screen and not the time it takes for the image to fully appear (which has to do with our Response Time measurements). Overall, the time it takes to display the image has a big impact on the total input lag.
Display lag is a phenomenon associated with most types of liquid crystal displays (LCDs) like smartphones and computers and nearly all types of high-definition televisions (HDTVs). It refers to latency, or lag between when the signal is sent to the display and when the display starts to show that signal. This lag time has been measured as high as 68 ms,Hz display. Display lag is not to be confused with pixel response time, which is the amount of time it takes for a pixel to change from one brightness value to another. Currently the majority of manufacturers quote the pixel response time, but neglect to report display lag.
For older analog cathode ray tube (CRT) technology, display lag is nearly zero, due to the nature of the technology, which does not have the ability to store image data before display. The picture signal is minimally processed internally, simply for demodulation from a radio-frequency (RF) carrier wave (for televisions), and then splitting into separate signals for the red, green, and blue electron guns, and for the timing of the vertical and horizontal sync. Image adjustments typically involve reshaping the signal waveform but without storage, so the image is written to the screen as fast as it is received, with only nanoseconds of delay for the signal to traverse the wiring inside the device from input to the screen.
For modern digital signals, significant computer processing power and memory storage is needed to prepare an input signal for display. For either over-the-air or cable TV, the same analog demodulation techniques are used, but after that, then the signal is converted to digital data, which must be decompressed using the MPEG codec, and rendered into an image bitmap stored in a frame buffer.
While the pixel response time of the display is usually listed in the monitor"s specifications, no manufacturers advertise the display lag of their displays, likely because the trend has been to increase display lag as manufacturers find more ways to process input at the display level before it is shown. Possible culprits are the processing overhead of HDCP, Digital Rights Management (DRM), and also DSP techniques employed to reduce the effects of ghosting – and the cause may vary depending on the model of display. Investigations have been performed by several technology-related websites, some of which are listed at the bottom of this article.
LCD, plasma, and DLP displays, unlike CRTs, have a native resolution. That is, they have a fixed grid of pixels on the screen that show the image sharpest when running at the native resolution (so nothing has to be scaled full-size which blurs the image). In order to display non-native resolutions, such displays must use video scalers, which are built into most modern monitors. As an example, a display that has a native resolution of 1600x1200 being provided a signal of 640x480 must scale width and height by 2.5x to display the image provided by the computer on the native pixels. In order to do this, while producing as few artifacts as possible, advanced signal processing is required, which can be a source of introduced latency. Interlaced video signals such as 480i and 1080i require a deinterlacing step that adds lag. Anecdotallyprogressive scanning mode. External devices have also been shown to reduce overall latency by providing faster image-space resizing algorithms than those present in the LCD screen.
Many LCDs also use a technology called "overdrive" which buffers several frames ahead and processes the image to reduce blurring and streaks left by ghosting. The effect is that everything is displayed on the screen several frames after it was transmitted by the video source.
Display lag can be measured using a test device such as the Video Signal Input Lag Tester. Despite its name, the device cannot independently measure input lag. It can only measure input lag and response time together.
Lacking a measurement device, measurement can be performed using a test display (the display being measured), a control display (usually a CRT) that would ideally have negligible display lag, a computer capable of mirroring an output to the two displays, stopwatch software, and a high-speed camera pointed at the two displays running the stopwatch program. The lag time is measured by taking a photograph of the displays running the stopwatch software, then subtracting the two times on the displays in the photograph. This method only measures the difference in display lag between two displays and cannot determine the absolute display lag of a single display. CRTs are preferable to use as a control display because their display lag is typically negligible. However, video mirroring does not guarantee that the same image will be sent to each display at the same point in time.
In the past it was seen as common knowledge that the results of this test were exact as they seemed to be easily reproducible, even when the displays were plugged into different ports and different cards, which suggested that the effect is attributable to the display and not the computer system. An in depth analysis that has been released on the German website Prad.de revealed that these assumptions have been wrong. Averaging measurements as described above lead to comparable results because they include the same amount of systematic errors. As seen on different monitor reviews the so determined values for the display lag for the very same monitor model differ by margins up to 16 ms or even more.
Several approaches to measure display lag have been restarted in slightly changed ways but still reintroduced old problems, that have already been solved by the former mentioned SMTT. One such method involves connecting a laptop to an HDTV through a composite connection and run a timecode that shows on the laptop"s screen and the HDTV simultaneously and recording both screens with a separate video recorder. When the video of both screens is paused, the difference in time shown on both displays have been interpreted as an estimation for the display lag.16 ms or even more.
Display lag contributes to the overall latency in the interface chain of the user"s inputs (mouse, keyboard, etc.) to the graphics card to the monitor. Depending on the monitor, display lag times between 10-68 ms have been measured. However, the effects of the delay on the user depend on each user"s own sensitivity to it.
Display lag is most noticeable in games (especially older video-game consoles), with different games affecting the perception of delay. For instance, in PvE, a slight input delay is not as critical compared to PvP, or to other games favoring quick reflexes like
If the game"s controller produces additional feedback (rumble, the Wii Remote"s speaker, etc.), then the display lag will cause this feedback to not accurately match up with the visuals on-screen, possibly causing extra disorientation (e.g. feeling the controller rumble a split second before a crash into a wall).
TV viewers can be affected as well. If a home theater receiver with external speakers is used, then the display lag causes the audio to be heard earlier than the picture is seen. "Early" audio is more jarring than "late" audio. Many home-theater receivers have a manual audio-delay adjustment which can be set to compensate for display latency.
Many televisions, scalers and other consumer-display devices now offer what is often called a "game mode" in which the extensive preprocessing responsible for additional lag is specifically sacrificed to decrease, but not eliminate, latency. While typically intended for videogame consoles, this feature is also useful for other interactive applications. Similar options have long been available on home audio hardware and modems for the same reason. Connection through VGA cable or component should eliminate perceivable input lag on many TVs even if they already have a game mode. Advanced post-processing is non existent on analog connection and the signal traverses without delay.
A television may have a picture mode that reduces display lag for computers. Some Samsung and LG televisions automatically reduce lag for a specific input port if the user renames the port to "PC".
LCD screens with a high response-time value often do not give satisfactory experience when viewing fast-moving images (they often leave streaks or blur; called ghosting). But an LCD screen with both high response time and significant display lag is unsuitable for playing fast-paced computer games or performing fast high-accuracy operations on the screen, due to the mouse cursor lagging behind.
One of the areas where the A-MVA panel does extremely well is in the areas of display lag and pixel response time. Just to recap, you may have heard complaints about "input lag" on various LCDs, so that"s one area we look at in our LCD reviews. We put input lag in quotation marks because while many people call it "input lag", the reality is that this lag occurs somewhere within the LCD panel circuitry, or perhaps even at the level of the liquid crystals. Where this lag occurs isn"t the concern; instead, we just want to measure the duration of the lag. That"s why we prefer to call it "processing lag" or "display lag".
To test for display lag, we run the Wings of Fury benchmark in 3DMark03, with the output set to the native LCD resolution - in this case 1920x1200. Our test system is a quad-core Q6600 running a Radeon HD 3870 on a Gigabyte GA-X38-DQ6 motherboard - we had to disable CrossFire support in order to output the content to both displays. We connect the test LCD and a reference LCD to two outputs from the Radeon 3870 and set the monitors to run in clone mode.
The reference Monitor is an HP LP3065, which we have found to be one of the best LCDs we currently possess in terms of not having display lag. (The lack of a built-in scaler probably has something to do with this.) While we know some of you would like us to compare performance to a CRT, that"s not something we have around our offices anymore. Instead, we are looking at relative performance, and it"s possible that the HP LP3065 has 20ms of lag compared to a good CRT - or maybe not. Either way, the relative lag is constant, so even if a CRT is faster at updating, we can at least see if an LCD is equal to or better than our reference display.
While the benchmark is looping, we snap a bunch of pictures of the two LCDs sitting side-by-side (using a relatively fast shutter speed). 3DMark03 shows the runtime with a resolution of 10ms at the bottom of the display, and we can use this to estimate whether a particular LCD has more or less processing lag than our reference LCD. We sort through the images and discard any where the times shown on the LCDs are not clearly legible, until we are left with 10 images for each test LCD. We record the difference in time relative to the HP LP3065 and average the 10 results to come up with an estimated processing lag value, with lower numbers being better. Negative numbers indicate a display is faster than the HP LP3065, while positive numbers mean the HP is faster and has less lag.
It"s important to note that this is merely an estimate - whatever the reference monitor happens to be, there are some inherent limitations. For one, LCDs only refresh their display 60 times per second, so we cannot specifically measure anything less than approximately 17ms with 100% accuracy. Second, the two LCDs can have mismatched vertical synchronizations, so it"s entirely possible to end up with a one frame difference on the time readout because of this. That"s why we average the results of 10 images, and we are confident that our test procedure can at least show when there is a consistent lag/internal processing delay. Here is a summary of our results for the displays we have tested so far.
As you can see, all of the S-PVA panels we have tested to date show a significant amount of input lag, ranging from 20ms up to 40ms. In contrast, the TN and S-IPS panels show little to no processing lag (relative to the HP LP3065). The BenQ FP241VW performs similarly to the TN and IPS panels, with an average display lag of 2ms - not something you would actually notice compared to other LCDs. Obviously, if you"re concerned with display lag at all, you"ll want to avoid S-PVA panels for the time being. That"s unfortunate, considering S-PVA panels perform very well in other areas.
Despite what the manufacturers might advertise as their average pixel response time, we found most of the LCDs are basically equal in this area - they all show roughly a one frame "lag", which equates to a response time of around 16ms. In our experience, processing lag is far more of a concern than pixel response times. Taking a closer look at just the FP241VW, we can see the typical one frame lag in terms of pixel response time. However, the panel does appear to be a little faster in response time than some of the other panels we"ve tested (notice how the "ghost image" isn"t as visible as on the HP LP3065), and we didn"t see parts of three frames in any of the test images.
After the initial article went live, one of our readers who works in the display industry sent me an email. He provides some interesting information about the causes of image lag. Below is an (edited) excerpt from his email. (He wished to remain anonymous.)
PVA and MVA have inherent drawbacks with respect to LCD response time, especially gray-to-gray. To address this shortcoming, companies have invested in ASICs that perform a trick generically referred to as "overshoot." The liquid crystal (LC) material in *VA responds sluggishly to small voltage changes (a change from one gray level to another). To fix this, the ASIC does some image processing and basically applies an overvoltage to the electrodes of the affected pixel to spur the LC material into rapid movement. Eventually the correct settling voltage is applied to hold the pixel at the required level matching the input drive level.
It"s very complicated math taking place in the ASIC in real time. It works well but with an important caveat: it requires a frame buffer. What this means is that as video comes into the panel, there is a memory device that can capture one whole video frame and hold it. After comparing it to the next incoming frame, the required overshoot calculations are made. Only then is the first captured frame released to the panel"s timing controller, which is when the frame is rendered to the screen. As you may have already guessed, that causes at least one frame time worth of lag (17ms).
Some companies discovered some unintended artifacts in their overshoot calculations and the only way they saw to correct these was to allow for their algorithm to look ahead by two frames instead of one. So they had to up the memory of the frame buffer and now they started capturing and holding not one but two frames upon which they make their complex overshoot predictions to apply the corrected pixel drive levels and reduce gray-to-gray response time (at the expense of lag time). Again, it works very well for improving response time, but at the expense of causing lag, which gamers hate. That in a nutshell is the basis of around 33ms of the lag measured with S-PVA.
Not every display uses this approach, but this could account for the increase in display lag between earlier S-PVA and later S-PVA panels. It"s also important to note that I tested the Dell 2408WFP revision A00, and apparently revision A01 does not have as much lag. I have not been able to confirm this personally, however. The above also suggest that displays designed to provide a higher image quality through various signal processing techniques could end up with more display lag caused by the microchip and microcode, which makes sense. Now all we need are better algorithms and technologies in order to reduce the need for all of this extra image processing -- or as we have seen with some displays (particularly HDTVs), the ability to disable the image processing.
Input lag is the amount of time it takes for a display to process a button input while gaming. If you value your gaming experience, you want to avoid displays that exhibit high input lag, as it makes your gameplay feel sluggish and unresponsive. Our input lag database below will help you avoid laggy displays, as it is the world’s largest database for input lag data.
Stick to displays marked Excellent for the best user experience, as they provide the lowest input lag when set to Game Mode. All displays are tested at 60hz. Most displays of the same model number share nearly identical input lag across size ranges.
We all know that PC games offer a myriad of customization options that aren’t found on traditional game consoles, allowing you to tweak the experience to your liking. Did you know it’s possible to change the latency of a PC game as well? Our last article explored console latency, explaining how your controller’s responsiveness is largely tied to the developer’s vision of their game. Due to PC being open architecture, it’s possible to tweak the latency of a PC game using a variety of options in your graphic card’s control panel, as well as third party programs.
A game that requires this level of tweaking is Ultra Street Fighter IV. The game was mainly designed for Nvidia architecture, which resulted in the PC, PlayStation 3, and arcade versions being similar to each other in terms of latency. However, the fighting game community started to notice that the Xbox 360 version of the game had lower input lag over other versions. I measured this difference in latency when I wrote my last article, and the difference is quite noticeable: the Xbox 360 version of USFIV averaged approximately 85ms of controller latency, whereas the PlayStation 3 version averaged approximately 107ms (check out our video game input lag database). While technically not “arcade perfect”, most players preferred the lower latency inherent within the Xbox 360 version, which may have been a result of it using an AMD-based GPU. For years, the PC version at stock settings felt very similar to the PlayStation 3 version, which I personally didn’t enjoy due to increased latency. It felt awkward and unnatural after playing on the Xbox 360 version for so long. However, after plenty of experimentation, it’s possible to match and/or exceed the speed of the Xbox 360 version! It’s important to note that all of the tweaks mentioned below can work on any current PC game, and not just Ultra Street Fighter IV. Experiment and see what feels best to you!
Input lag in video games is a result of two main things: frame rate and V-Sync implementation. On consoles, it usually isn’t possible to customize these options, resulting in a static controller response that is set forth by the developer. PC gaming doesn’t adhere to this restriction. In the following examples, Ultra Street Fighter IV is utilized as our preferred testing benchmark. Latency is measured after applying various configurations detailed in this article. Ultra Street Fighter IV is capped at 60 frames per second, so we utilize our
To achieve the lowest possible controller latency, the best option is to completely disable vertical sync. V-Sync is a function that allows the game to synchronize it’s frame rate with the refresh rate of the display. Disabling it removes the frame rate cap, which also causes massive amounts of screen tearing. The screen tearing exhibited by the lack of V-Sync can be very distracting to most gamers. If reducing input lag is your primary concern, then this is your best option. Ultra Street Fighter IV achieves an ultra-low 59ms (3.6 frames) of controller latency with all V-Sync options disabled on our Nvidia GPU, and 61ms (3.7 frames) of controller latency on our AMD Radeon GPU.
Every PC game on the market comes shipped with it’s own V-Sync option that can be toggled in the configuration menu of the game itself. Most of the time, this is the only option you’ll need for a smooth experience. However, it may not be the option with the lowest input lag. The stock V-Sync option in Ultra Street Fighter IV provides a base latency of 103ms (6.2 frames) of input lag, which is very similar to the PlayStation 3 version that measured 107ms (6.4 frames). Enabling V-Sync synchronizes the game with the refresh rate of the display to remove screen tearing, however it also adds around 2 frames of input lag in most cases. Enabling V-Sync in-game results in a controller latency of 103ms (6.2 frames) on our Nvidia GPU, and 102ms (6.1 frames) on our AMD Radeon GPU. In-game V-Sync under CrossFireX resulted in 103ms (6.2 frames) of input lag, though make sure frame pacing is set to ON within Catalyst Control Center. Disabling frame pacing results in an extremely high input lag of 143ms (8.6 frames), so you definitely want to avoid that scenario!
If a game suffers from poor V-Sync implementation, it is possible to force V-Sync through the GPU control panel itself, which may sometimes offer a better experience. Both Nvidia and AMD allow forced V-Sync via control panel, however only Nvidia’s forced V-Sync option worked in Ultra Street Fighter IV. The game presents slightly higher controller latency when forcing V-Sync via the control panel, with a controller latency of 109ms (6.6 frames). Forcing V-Sync on our GTX 970 SLI setup increased input lag over a singular GPU, bringing the latency up to 114ms (6.9 frames) However, it is possible to reduce latency further by configuring maximum pre-rendered frames (explained below).
This setting is buried under the “Manage 3D Settings” page in the Nvidia control panel. Maximum pre-rendered frames is a setting that governs the amount of frames the CPU is able to process before handing it off to the GPU. The default value is set to 3, which typically achieves the best balance between input lag and a smooth image. If you have a particularly powerful GPU, you can reduce this value in order to achieve significantly lower input lag, without any noticeable downsides. Setting it to 1 prevents the CPU from processing more frames than it needs to, allowing the GPU to do most of the grunt work. In Ultra Street Fighter IV, combining control panel V-Sync with a maximum pre-rendered frames (1) setting results in 95ms (5.7 frames) of controller latency, whereas keeping in-game V-Sync enabled with the maximum pre-rendered frames (1) setting resulted in 101ms (6.1 frames) of controller latency. On AMD Radeon GPUs, this setting is known as flip queue. You can configure this option by downloading the RadeonPro application, which allows deeper tweaking of your Radeon GPU. Forcing a flip queue setting of 1 resulted in an average input lag of 97ms (5.8 frames). Both AMD Catalyst Control Center and RadeonPro were unable to force V-Sync in Ultra Street Fighter IV. In-game V-Sync was used along with flip queue (1) setting within RadeonPro in order to achieve lower input lag for our Radeon GPU.
The Smooth V-Sync option is largely overlooked since Nvidia introduced it in 2013, though its importance in a multi-GPU setup shouldn’t be underestimated. Smooth V-Sync attempts to keep the frame rate at the most sustainable level. If your game constantly fluctuates between 30 and 60 FPS, there is a good chance that enabling Smooth V-Sync will lock you to 30 FPS throughout your gaming session, in order to provide the most consistent experience. There will be times where you will encounter an area of the game entirely in 30 FPS, then have it switch back to a higher frame rate when nothing is taxing your GPUs. The importance of Smooth V-Sync lies within games your SLI setup completely dominates. Ultra Street Fighter IV can be comfortably maxed out at 4K resolution on our singular GTX 970, so why bother enabling a secondary GPU? Because Smooth V-Sync allows for dramatic input lag reduction! Running Ultra Street Fighter IV on our Nvidia GTX 970 SLI setup with Smooth V-Sync active resulted in an average input latency of 87ms (5.2 frames), offering the lowest amount of input lag when compared to every other Nvidia V-Sync solution (with the exception of V-Sync OFF and G-SYNC).
It is possible to completely bypass control panel and in-game V-Sync options to utilize Windows’ native V-Sync implementation, which is also triple-buffered. By running the game in a window or borderless window, Windows handles the vertical synchronization, which can lead to smoother gameplay and lower input lag. Make sure you disable V-Sync in all other areas before doing so. Running Ultra Street Fighter IV in a window reduces input lag over both in-game and stock control panel V-Sync, with a controller latency of 98ms (5.9 frames) on our Nvidia GPU, significantly higher than AMD Radeon’s 81ms (4.9 frames) of latency under the same scenario. It’s also possible to utilize windowed V-Sync in both SLI and CrossFireX setups. On Nvidia’s SLI setup, we measured 95ms (5.7 frames) of controller latency, which is still higher than CrossFireX’s measured latency of 87ms (5.2 frames). Utilizing Windows’ built in V-Sync may not always be smooth sailing however, and can sometimes cause stuttering that is absent when running the game in fullscreen mode.
It gets even better. In 2013, Nvidia announced a complete V-Sync replacement known as G-SYNC. G-SYNC provides the benefits of V-Sync’s tear-free image, without the stuttering and input lag associated with traditional V-Sync. The technology allows the display to directly communicate with the GPU, bypassing the ruleset of traditional V-Sync entirely. Shortly after, AMD announced its own variable refresh rate technology known as Adaptive-Sync/FreeSync. The only catch to these technologies is the requirement of a newer display tailored for your specific GPU. I managed to test the benefits of both G-SYNC and Adaptive-Sync, and the results are simply incredible.
Bypassing all other forms of V-Sync, enabling G-SYNC within Nvidia’s control panel resulted in an enormous reduction of input lag. In most cases, connecting your Nvidia GeForce GPU to a G-SYNC monitor will automatically enable G-SYNC, though this setting can be enabled manually and tailored to specific games via the control panel. After connecting the GTX 970 to our This is significantly lower than even the lowest recorded values from our V-Sync tests above. Nvidia also allows SLI users to partake in the G-SYNC ceremony. Running Ultra Street Fighter IV with G-SYNC active on our SLI setup resulted in a slightly higher latency measurement of 63ms (3.8 frames).
There are a few other methods that can reduce input lag within PC games. One of them involves using a frame limiter to set your maximum frames per second below the refresh rate of your display. You can cap your game at 59 frames per second on a 60hz monitor to reduce input lag considerably, however this will more than likely cause some stuttering in games that run best at a locked frame rate. Ultra Street Fighter IV requires a steady 60 FPS, and limiting it below this frame rate can cause some issues. Another way to reduce input latency is by enabling a higher refresh rate. While Ultra Street Fighter IV is capped at 60 FPS due to its gameplay mechanics, many other genres such as first person shooters are able to go above and beyond 60 FPS. Running a game at 120hz or 144hz can reduce input lag by over 50%, as long as your hardware is powerful enough to handle it! On top of reduced latency, motion will appear silky smooth, which can ruin your perception of 60hz if that’s all you’re used to!
There are several ways to change the feel of your favorite PC game by employing the methods detailed above. While the results can vary by game, it is important to try these options if you are unsatisfied with the latency associated with default settings. One thing is clear, however: the absolute best way to reduce input latency while keeping a tear-free image is to acquire a G-SYNC or FreeSync display. For those on a budget, be sure to try the tweaks listed above and report your experiences in the comments below!
Yes we all know that CRTs have the lowest input lag of any display ever made. The problem with this longstanding fact is that any non-CRT screen is shunned by smashers as if they might contract the bubonic plague instantly upon use.
There has been talk of LCD monitors being used at upcoming international events such as Evo. This talk, as expected, has elicited a negative reaction from many smashers. The primary goal of this article is to outline just how close these monitors can get to the response time of a CRT, what the effect of lag is on gameplay, and to dispel some myths people have about LCD monitors.
In order to determine if a particular monitor lags, people will often try the subjective strategy. That is, they ask a smasher to play on a monitor and comment on how it feels. This strategy usually results in comments such as:
With that said, it makes sense to attempt an objective strategy. With some help from Mofo, I developed a method for objectively testing lag on any type of screen. One of the beautiful things about this method is that it actually uses melee itself as part of the test. This means that we can say for a fact that every single possible source of lag has been accounted for.
As players, the lag we are sensitive to is the time between when an input is pressed to the time when the game’s reaction to that input appears on screen. In simpler words, lag is when stuff happens later than it should.
The game itself, however, cannot physically react to inputs immediately when they are received. This is because the game operates in discrete frames. For example, a character’s move can only ever begin on a frame, it cannot begin at any point in between. That said, players can and do press buttons in the time between frames. This means that if the A button is pushed to jab, the game will only begin the jab startup in a variable amount of time between 0 ms and 16.66 ms (length of one frame) – it will not start the jab immediately upon receiving the input.
They understand the margin of error and press inputs in consequence to this. In the above graphic this would mean adding some time between button presses to guarantee the timing is always met
The point to make here is that, even on a monitor that is lagless, lag still exists in some way. A fully lagless experience is impossible. One way or another, players are capable of dealing with some lag. Lag induced by a laggy screen, however, is an added constant on top of this variable lag – the effect of which will be explored later.
The original concept for determining the latency of a monitor was to somehow detect the time difference between when an input is pressed to when a particular frame shows up on screen. Unfortunately, this approach is iffy at best for the reasons described in the previous section. The result of such a test would be (true lag) + (time until next frame) where time until next frame is between 0 and 16.66 ms. Luckily, there is another signal that is separate from the video and yet is related to it time wise – sound.
Let’s consider Captain Falcon standing on FD about to falcon punch. When the b button is registered by the console, the console will send the video frame information consistent with displaying a falcon punch as well as the sound information containing the famous words “FALCON PUNCH!”. The sound and the video will always be sent out by the console at the same times respective to each other, irrespective of where the input landed in the subframe region.
When the video signal reaches the display, it is first processed, and then displayed. This processing time is effectively the lag of the monitor – it will cause the two signals, audio and video, to appear desynchronized. It is the amount of time of this desynchronization that will be measured to determine lag.
When this test is executed on a CRT, the gold standard for response time, a time difference is obtained from step 4. This time difference is the expected value required if another system is to be called truly lagless.
When this test is executed on a laggy monitor, the time difference will be greater than what was seen on the CRT. The audio output will be detected at the same time but the pause decal will show up at some time later. The lag of this TV can then be calculated by the formula:
There are a few sources of error in the testing method. In order to improve the accuracy of the results, the test was executed multiple times on each monitor and the results averaged. That said, there is likely still about plus or minus 1 ms of error for the LCD results.
CRTs have less error associated with their measurement because determining when the video signal has appeared is less subjective. On an LCD, as can be seen in the gif above, the decal shows up in an incomplete fashion before the signal is accepted. This is done to provide a more fair comparison to the CRT – on which the top part of the decal is instantly fully clear.
If you have ever been introduced to the website www.displaylag.com, you might wonder how it is possible for the results to be so low with the RL2455HM.
The RL2455HM monitor displays a frame from top to bottom. This method of showing a frame is identical to how a CRT displays a frame. Display lag database uses the average latency across three zones (top, center, and bottom). Using this metric, even a CRT would not have zero lag – it would have 8.3 ms of lag. This is because it takes a full 16.66 ms to display the entire frame from top to bottom. In this particular case and in many others, when comparing to a CRT it is more fair to subtract about 8 ms from the number reported by Display Lag.
It is important to make a distinction between events that are affected by monitor lag and events that are not. Events that are executed via muscle memory timing, pressing one button at the correct timing after another, such as a wavedash are very easy to execute even on very laggy monitors because they do not utilize much visual prompting.
Let’s consider a person who can successfully power shield a laser 95% of the time. Assuming that human reaction follows the gaussian pattern, a gaussian response that could meet this success rate has a mean at 1 frame before the laser hits and a variance of about 72.25 (ms). Introducing the lag of the monitor and assuming that the distribution is shifted over by an amount equal to the lag, the probability of a successful power shield only drops to 93.7%.
Now a 95% success rate on a power shield is rather good. Let’s assume the person is still good but not super human – they have a lower success rate of 50% caused by an increase in variance. Given the same amount of lag, their success rate only drops to 49.7%. The takeaway from this is that given a higher variance, larger variation in a person’s ability to respond in a given amount of time, the effect of monitor latency diminishes.
It is also possible for the mean to not be perfectly centered along the target area. For example, consider a person has the same variance as described in the first example – a variance which signifies the person is quite proficient at hitting a 2 frame window. Now consider that this person tends to power shield late, late enough that their success rate is only 62.3% on a lagless system. With the lag added, this person’s success rate would drop to 49.1%. This scenario is just about the worst case given this kind of variance. The best case scenario is when the lag actually helps the player. If the same person had a tendency to hit early instead, their success rate would actually increase from 62.3% to 74.2%.
Now let’s talk about if the lag was a bit worse. Let’s consider a monitor that is slow by one full frame, 16.66 ms. In the first example with the 95% success rate person, their rate on this monitor would drop all the way to 50%. That is, 93.7% on a 2.86 ms monitor, 50% on a 16.66 ms monitor. This highlights the fact that there is a major difference between a monitor that is pretty good and one that is very good. Most monitors that people have tried would likely fall under the “pretty good” category at best. Do not allow past experiences with other monitors to influence your conception of these “very good” monitors.
All the calculations in this section were made under the assumption that the human does not adapt to the new lag. It may also be possible that the brain notices the slight offset and corrects to some degree. If the brain does do some correction, then the difference would be even smaller than described.
By the reasoning outlined in the previous section, minor lag does not appear to be a major factor for player performance. That said, I ask the reader, have you ever heard someone claim that some CRTs lag? Why do people think this? In my test results, CRT 2 is a 14 inch CRT. I have heard many negative comments about CRT 2. People just don’t seem to like it, often claiming that it lags. As shown by the results, the lag difference is essentially non-existent – it is well within the error of the test. So then, why do people not like it?
The takeaway here is that lag is not the only problem with a screen. When an image looks different than another, it can throw a player off. This precise issue leads to one of the most powerful arguments for having a pro-LCD position. All the screens are the same. No more swapping back and forth between small CRTs and large CRTs. No more old, ugly, discolored CRTs. No more terrible terrible audio. The same image – same experience – every time.
Everyone has noticed the growth which our exposure at Evo provided. These big events are paramount to our continued growth. If dealing with an extremely small amount of delay helps aid that cause, how can you not support it? This small amount of lag, by the way, is bound to reduce even further as the technology improves. Maybe our exposure at these big events and our willingness to try new technology will encourage companies like BenQ or Asus to come out with new monitors that are even better for our use – monitors with support for native component input, or even maybe composite inputs.
The most exciting, fast-paced games—like shooters, fighters, or racing sims—are built around the assumption that split-second reactions will actually happen within a split-second on your screen. When they don"t, it"s a major immersion breaker, and input lag is usually the culprit.
Input lag refers to the total difference in time between you moving a controller of some kind (a mouse, keyboard, or gamepad) and a response on screen. Input lag can happen at every step along the signal chain—from the controller, to the console, to the screen—and it"s cumulative; if the controller, game, and TV each introduce 30 milliseconds of delay, you"ll get a total of 90ms input lag.
Though there are ways to analyze just the input lag of any display, we wanted to look at the problem holistically. We also wanted to tackle this from a gamer"s perspective, comparing the experience of playing on a TV with both a traditional console and a PC. To that end for both our PC and game console tests we used a wired Xbox 360 controller and played the same game: Skyrim.
Then, we used the GoPro Hero4 Silver (set to 720p at 120 FPS) to record us repeating the same inputs across all our various test setups. By reviewing the footage and counting the frames (with each frame recording an 8.33ms slice of time) we were able to measure how much delay each setup introduced.
We started our experiment with an Xbox 360 outputting via composite (AV) cables to an old-school CRT television. Why a CRT? Because though they"re big and bulky, CRTs introduce almost no lag; as soon as the console sends out a signal, the TV will display it. With a CRT we were able to see a base input lag of about 139ms, with about 40-50ms taken up by our controller input and the rest from the console itself. Generally anything less than 166ms (about 10 frames of a game running at 60 FPS) is considered negligible, so this is a perfect result.
We repeated the test on four other types of TVs, including a plasma, 1080p LED, an older CCFL LCD, and the 2014 P-series 4K LED from Vizio. All four of these sets include analog (composite and component) and digital (HDMI) inputs. In general we found HDMI presented the best results on modern TVs with a modern game console. The only exception is the older CCFL LCD, which performed marginally better with component cables.
Despite having a lightning fast refresh rate, the plasma was the worst performer—though our particular Samsung plasma is well-known for having input lag issues. The CCFL LCD and the 1080p LED were both about the same, oddly enough, though the game looked much better on the modern display.
The most surprising result? The Vizio 4K TV was the best performer after the CRT, as long as you stick to one particular HDMI input. This is because while most HDMI inputs top out at 60Hz (50Hz in PAL countries), this Vizio has a "High Velocity" HDMI input that supports 4K/60Hz or 1080/120Hz throughput. Even though this set has to upscale the Xbox"s HD image to 4K, using this port reduced input lag severely. On any other HDMI port the TV"s total input lag was a sky-high 292ms.
For PC gamers looking to move to the living room, we wanted to stick with the same setup. We replaced our Xbox 360 with a powerful gaming laptop, the Razer Blade Pro, which has a 2.4Ghz Intel Core i7-4700HQ processor, 16GB of RAM, and an Nvidia Geforce 860M graphics card. We omitted the CRT and CCFL LCD because they both have sub-1080p resolutions, leaving the plasma, LED LCD, 4K LCD, and the laptop"s screen to contend for the gold.
Our initial results were positive: Gaming directly to your laptop"s screen presents the least amount of input lag—even less than gaming with the Xbox 360 and a CRT. In fact, across the board we saw lower input lag when using a modern gaming laptop than when performing the same inputs on the Xbox 360.
The most surprising result? When running the PC version of Skyrim on Ultra settings at 1080/60 FPS, the 4K Vizio had only slightly more input lag than playing the Xbox 360 version of Skyrim on a CRT monitor. The laptop"s own screen is still king, but remember (again) that the Vizio is upscaling that 1080p image to display it at 4K. Again, it"s essential that you use the high-speed HDMI port as all the standard HDMI ports had an input lag of over 300ms.
The short answer is yes, especially if your TV"s native resolution is 1080p or higher. If you have an older TV—say from 2006 or 2007—with sub-1080p resolution, you may find that the interlaced 1080i signal (from a component input) is a little faster at the cost to some image clarity. If you"re using a 4K set then definitely opt for HDMI, but without a faster HDMI port the upscaling process will introduce significant levels of lag.
If you"re playing on older consoles: The tradeoffs are pretty obvious; you can play a Wii, Xbox 360, PS3, or any older console on a CRT if you absolutely want the best input lag—something competitive fighting game players have known for years. This means missing out on larger, better-looking screens, however. Modern LCDs like the one we tested can introduce 20 milliseconds or more of perceptible lag (over 166 ms). And while plasma performance may be better than LCD in terms of image quality, it sometimes means tons of additional input lag.
If you"re playing on a new console: You shouldn"t be afraid to make the jump to a 4K TV as long as it upscales well and has a "fast" HDMI input like the P Series. While games on the PS4 and Xbox One will likely top out at 1080/60 FPS this generation, the input lag from 4K upscaling is negligible—with the right port. If you"re buying a new TV, make sure it has HDMI 2.0 ports that support HDCP 2.2
If you"re a PC gamer: A full-on gaming rig is clearly the best bet for avoiding input lag. And with a laptop, playing directly to the screen is just as fast as using an older console and a CRT. If you"re set on gaming in the living room, the same rules apply: Look for a new UHD TV with faster HDMI inputs, or 1080p displays with game modes available. And while 4K gaming is cool, gaming at a consistent 60 FPS is more important.
Ultimately, input lag is the sum of many parts. There are individual variables from set to set and game to game that will affect input lag. If you want to learn more about what a specific display will add to the equation, we recommend DisplayLag"s invaluable Input Lag Database to help you get your twitch on.
Your monitor’s display settings may increase the delay between inputting commands and seeing the result on your display. Some display parameters are configurable, while others are built into the hardware and cannot be changed.
The first thing to look at is your monitor’s refresh rate. A higher refresh rate increases the number of individual frames that your monitor displays per second. Displaying more frames per second reduces the delay between inputting a command and seeing its result on the screen, shaving valuable milliseconds off input lag.
Not all wired connections provide the same response time benefits. Some displays (especially Smart TVs) add processing effects like visual noise reduction to AV input, which adds to latency. To avoid this, check to see if your TV features a “Game Mode” that minimizes input lag by bypassing video signal processing.
Keep in mind that every TV and monitor has a unique, hardware-defined input latency. This is the amount of time that it takes the display to receive, process, and show incoming data. It is built into the hardware of the screen itself and cannot be changed.
Manufacturers don’t generally advertise their products’ latency delays. Instead, they focus on “response time,” which measures how long it takes for individual pixels to change color. It’s easy to confuse these two, but response time doesn’t have a significant impact on input lag.
Many new, gaming-ready displays have an input latency of 10-15 milliseconds. There are third-party websites that conduct and list monitor input latency scores, so it’s possible to verify how much of your input lag is built in.
- For more accurate measurements, do both black/white and inverse white/black tests, and average the results. LCD GtG pixel transitions are often asymmetric.
So, why is this important? A monitor’s panel technology is important because it affects what the monitor can do and for which uses it is best suited. Each of the monitor panel types listed above offer their own distinctive benefits and drawbacks.
Choosing which type of monitor panel type to buy will depend largely on your intended usage and personal preference. After all, gamers, graphic designers, and office workers all have different requirements. Specific types of displays are best suited for different usage scenarios.
The reason for this is because none of the different monitor panel types as they are today can be classified as “outstanding” for all of the attributes mentioned above.
Below we’ll take a look at how IPS, TN, and VA monitors affect screen performance and do some handy summaries of strengths, weaknesses, and best-case uses for each type of panel technology.
IPS monitors or “In-Plane Switching” monitors, leverage liquid crystals aligned in parallel to produce rich colors. IPS panels are defined by the shifting patterns of their liquid crystals. These monitors were designed to overcome the limitations of TN panels. The liquid crystal’s ability to shift horizontally creates better viewing angles.
IPS monitor variations include S-IPS, H-IPS, e-IPS and P-IPS, and PLS (Plane-to-Line Switching), the latter being the latest iteration. Since these variations are all quite similar, they are all collectively referred to as “IPS-type” panels. They all claim to deliver the major benefits associated with IPS monitors – great color and ultra-wide viewing angles.
With regard to gaming, some criticisms IPS monitors include more visible motion blur coming as a result of slower response times, however the impact of motion blur will vary from user to user. In fact, mixed opinions about the “drawbacks” of IPS monitor for gaming can be found all across the web. Take this excerpt from one gaming technology writer for example: “As for pixel response, opinions vary. I personally think IPS panels are quick enough for almost all gaming. If your gaming life is absolutely and exclusively about hair-trigger shooters, OK, you’ll want the fastest response, lowest latency LCD monitor. And that means TN. For the rest of us, and certainly for those who place even a modicum of importance on the visual spectacle of games, I reckon IPS is clearly the best panel technology.” Read the full article here.
IPS monitors deliver ultra-wide 178-degree vertical and horizontal viewing angles. Graphic designers, CAD engineers, pro photographers, and video editors will benefit from using an IPS monitor. Many value the color benefits of IPS monitors and tech advances have improved IPS panel speed, contrast, and resolution. IPS monitors are more attractive than ever for general desktop work as well as many types of gaming. They’re even versatile enough to be used in different monitor styles, so if you’ve ever compared an ultrawide vs. dual monitor setup or considered the benefits of curved vs. flat monitors, chances are you’ve already come into contact with an IPS panel.
TN monitors, or “Twisted Nematic” monitors, are the oldest LCD panel types around. TN panels cost less than their IPS and VA counterparts and are a popular mainstream display technology for desktop and laptop displays.
Despite their lower perceived value, TN-based displays are the panel type preferred by competitive gamers. The reason for this is because TN panels can achieve a rapid response time and the fastest refresh rates on the market (like this 240Hz eSports monitor). To this effect, TN monitors are able to reduce blurring and screen tearing in fast-paced games when compared to an IPS or VA panel.
On the flip side, however, TN panel technology tends to be ill-suited for applications that benefit from wider viewing angles, higher contrast ratios, and better color accuracy. That being said, LED technology has helped shift the perspective and today’s LED-backlit TN models offer higher brightness along with better blacks and higher contrast ratios.
The greatest constraint of TN panel technology, however, is a narrower viewing angle as TN monitors experience more color shifting than other types of panels when being viewed at an angle.
Today’s maximum possible viewing angles are 178 degrees both horizontally and vertically (178º/178º), yet TN panels are limited to viewing angles of approximately 170 degrees horizontal and 160 degrees vertical (170º /160º).
TN monitors are the least expensive panel technology, making them ideal for cost-conscious businesses and consumers. In addition, TN monitors enjoy unmatched popularity with competitive gamers and other users who seek rapid graphics display.
Vertical alignment (VA) panel technology was developed to improve upon the drawbacks of TN. Current VA-based monitors offer muchhigher contrast, better color reproduction, and wider viewing angles than TN panels. Variations you may see include P-MVA, S-MVA, and AMVA (Advanced MVA).
These high-end VA-type monitors rival IPS monitors as the best panel technology for professional-level color-critical applications. One of the standout features of VA technology is that it is particularly good at blocking light from the backlight when it’s not needed. This enables VA panels to display deeper blacks and static contrast ratios of up to several times higher than the other LCD technologies. The benefit of this is that VA monitors with high contrast ratios can deliver intense blacks and richer colors.
MVA and other recent VA technologies offer the highest static contrast ratios of any panel technology. This allows for an outstanding visual experience for movie enthusiasts and other users seeking depth of detail. Higher-end, feature-rich MVA displays offer the consistent, authentic color representation needed by graphic designers and other pro users.
There is another type of panel technology that differs from the monitor types discussed above and that is OLED or “Organic Light Emitting Diode” technology. OLEDs differ from LCDs because they use positively/negatively charged ions to light up every pixel individually, while LCDs use a backlight, which can create an unwanted glow. OLEDs avoid screen glow (and create darker blacks) by not using a backlight. One of the drawbacks of OLED technology is that it is usually pricier than any of the other types of technology explained.
When it comes to choosing the right LCD panel technology, there is no single right answer. Each of the three primary technologies offers distinct strengths and weaknesses. Looking at different features and specs helps you identify which monitor best fits your needs.
LCD or “Liquid Crystal Display” is a type of monitor panel that embraces thin layers of liquid crystals sandwiched between two layers of filters and electrodes.
While CRT monitors used to fire electrons against glass surfaces, LCD monitors operate using backlights and liquid crystals. The LCD panel is a flat sheet of material that contains layers of filters, glass, electrodes, liquid crystals, and a backlight. Polarized light (meaning only half of it shines through) is directed towards a rectangular grid of liquid crystals and beamed through.
Note: When searching for monitors you can be sure to come across the term “LED Panel” at some point or another. An LED panel is an LCD screen with an LED – (Light Emitting Diode) – backlight. LEDs provide a brighter light source while using much less energy. They also have the ability to produce white color, in addition to traditional RGB color, and are the panel type used in HDR monitors.
Early LCD panels used passive-matrix technology and were criticized for blurry imagery. The reason for this is because quick image changes require liquid crystals to change phase quickly and passive matrix technology was limited in terms of how quickly liquid crystals could change phase.
Thanks to active-matrix technology, LCD monitor panels were able to change images very quickly and the technology began being used by newer LCD panels.
Ultimately, budget and feature preferences will determine the best fit for each user. Among the available monitors of each panel type there will also be a range of price points and feature sets. Additionally, overall quality may vary among manufacturers due to factors related to a display’s components, manufacturing, and design.
Alternatively, if you’re into gaming and are in the market for TN panel these gaming monitor options may be along the lines of what you’re looking for.
Low input latency is key to a satisfying experience in competitive games, but reasoning about latency can be non-intuitive in modern engines with multiple parallel timelines running at once. This talk will tackle latency by analyzing the path that data flows through a game engine from the input sample all the way to the video scan-out hardware. By identifying and measuring segments on this path, a dynamic throttle can be implemented to squeeze the input sample as close to the end of the frame as possible without dropping frames. Special attention will be placed on how latency is introduced in the interaction between the GPU and display scan-out timelines when Vsync is enabled.