Monday, September 08, 2008

LCD HDTV Input Lag Tests

Input lag is something that many HDTV's have but isn't often covered in reviews. Basically, it's the amount of time it takes between receiving the video signal and the time it is displayed. With all the fancy processing HDTV's do these days (deinterlacing, scaling, image enhancement, motion compensation, etc) it can take precious milliseconds before the image is displayed. Normally this isn't such a big deal during normal viewing but for gamers it can be quite annoying especially if the game requires very quick and precise timing (think rhythm music games, fighting games, some sports games like golf, arcade style titles like Geometry Wars, active reload on gears of war, etc).

Here is a great article on HDTV Input Lag:
http://hdtvlag.googlepages.com/home
Specifically, I was most interested on how to measure and test for input lag. The idea is to playback a video with a 30fps timecode on a laptop. Connect the TV out on the laptop to a CRT first to get a baseline of how laggy the laptop monitor is compared to a CRT. We are assuming the CRT is 0ms lag. Then you just move the the laptop to the hdtv and run the tests again. Each frame it lags behind equals 33ms (1/30).

For each TV I took several shots (20+) using manual, no flash, iso 800, continuous shot mode. From there I sorted through them and looked for the best, average, and worst shots. I will also be testing regular picture mode and game mode where applicable. Game mode is usually a special mode on some HDTV's that is specifically designed to reduce input lag. The draw back of Game Mode is often you can't adjust any picture settings though I've read Sony lets you (and so does my Sharp). Another option is using VGA if possible which usually has less input lag.

This is a worst case scenario test. The laptop desktop resolution was set to 800X600 but is outputting 480i over composite. The TV has to do a lot of processing (analog to digital, deinterlace, scale, etc). Your modern day gaming console would probably be on HDMI outputting the native resolution of the TV. So when gaming on a pS3 or xbox 360 I would expect there to be less input lag than what these tests show.

UPDATE: I decided to expand the number of tests. First, I've added another baseline: 14" MAG LCD monitor which I will compare against the CRT. Since every HDTV has an htpc already hooked up to it, I plan to move the 14" MAG around hooking it up to each htpc and compare against the hdtv so I can test HDMI. I'll be using 720p since the MAG's native resolution is only 1024X768(but it will take higher resolutions and scale them down). There's one problem with this. I'm not taking into account that scaling of 720p on the MAG since when I baselined it against the CRT I used the native resolution of 1024X768. So just keep that in mind. I'll also be using the Laptop to test VGA at 1024X768. Finally I've added a millisecond stopwatch along with the 30 fps timecode video. Both have issues. Flash might not be the most accurate. Also, since pc video cards mostly output at 60hz, you are now way outputting or displaying every frame change on a millisecond stopwatch. Couple that with my old point and shoot canon sd700 camera with no way to adjust shutter speed (I did try the kids&pets mode) and poor lighting and you've got even more things to consider. So basically I'm not sure how precise or accurate the data is. I'll just present what I've collected, and let you be the judge.

Baseline (Laptop/CRT, 480i, timecode video).
It's my last CRT in the house. Hmmm....maybe I shouldn't be so quick on trying to get rid of it.

Here we can see the laptop LCD screen lags just a tiny bit. Lets say it's around 5ms. That means we must add 5ms to all the other tests.

Baseline (Laptop/CRT, 480i, stopwatch)

Looks nearly 0ms but lets just say 5ms to be on the conservative side.

Baseline (Mag/CRT, 480i, timecode video)

half a frame, maybe a bit less? Lets say 10ms since it does look more laggy than the laptop.

Baseline (Mag/CRT, 480i, stopwatch)

looks nearly 0ms to me. I'll just use 10ms to keep it consistent.


Samsung LN46A630 (baseline: laptop, 480i, timecode video)
This is my newest TV which I just bought. I also tested HDMI2 renamed to PC in addition to Game Mode.

Looks like just around 2 frames of lag so about 71ms lag (33 X 2 + 5).

baseline: Laptop, 480i, stopwatch

105ms (100 + 5)

baseline: laptop, 480i, timecode video, Game Mode

Looks like around 1.2 frames so about 45ms.

baseline: Laptop, 480i, stopwatch, Game Mode

65ms

baseline: Mag, 720p, timecode video, HDMI

a bit less than 1 frame, 40ms (30 + 10)

baseline: Mag, 720p, stopwatch, HDMI

41ms (31 + 10)

baseline: Mag, 720p, timecode video, HDMI, Game Mode

1 frame, 43ms

baseline: Mag, 720p, stopwatch, HDMI, Game Mode

40ms

baseline: Mag, 720p, timecode video, HDMI, PC

2 frames, 76ms

baseline: Mag, 720p, stopwatch, HDMI, PC

80ms

baseline: Mag, 1024X768, timecode video, VGA

half a frame, 26ms

baseline: Mag, 1024X768, stopwatch, VGA

30ms


Sharp LC-52D64U. (baseline: laptop, 480i, timecode video)

I picked this up about a year ago. The nice part about this TV is it does allow full picture settings adjustments even in Game Mode.
User Mode:

Maybe 2.75 frames so about 96ms.

baseline: laptop, 480i, stopwatch

105ms

baseline: laptop, 480i, timecode video, game mode

Looks like 1 frame to me so 38ms.

baseline: laptop, 480i, stopwatch, game mode

45ms

baseline: Mag, 720p, timecode video, hdmi

1 frame, 43ms

baseline: Mag, 720p, stopwatch, hdmi

40ms

baseline: Mag, 720p, timecode video, hdmi, game mode

1 frame, 43ms

baseline: Mag, 720p, stopwatch, hdmi, game mode

30ms

baseline: laptop, 720p, timecode video, VGA (I did test this vga in game mode too but I didn't notice any difference. That's right. Sharp lets you choose game mode on vga!)

half a frame, 22ms

baseline: laptop, 720p, stopwatch, VGA

25ms


Samsung LN-R409D (baseline: laptop, 480i, timecode video)
This was my first HDTV which I got almost 3 yrs ago. It doesn't have a game mode but I read some places that if you rename the input to "GAME" it helps. I'm not so sure about that but I did name the input GAME before testing.

Looks like around 1.8 frames so 64ms.

baseline: laptop, 480i, stopwatch

45ms

baseline: laptop, 1024X768, timecode video, VGA

1.25 frames, 46ms

baseline: laptop, 1024X768, stopwatch, VGA

51ms

baseline: Mag, 720p, timecode video, hdmi

1 frame, 43ms

baseline: Mag, 720p, stopwatch, hdmi

41ms


Summary:
Times are listed in milliseconds. First value is computed using the timecode video / second value is computed using the millisecond stopwatch. Baseline values are already included in the posted times.
TV 480i Composite Standard Mode 480i Composite Game Mode 720p HDMI 720p HDMI Game Mode 720p HDMI PC Rename 1024 X768 VGA
CRT 0/0
Laptop 5/5
14" MAG LCD Monitor 10/10
Samsung LN46A630 71/105 45/65 40/41 43/40 76/80 26/30
Sharp LC-52D64U 96/105 38/45 43/40 43/30 NA 22/25
Samsung LN-R409D 64/45 NA 43/41 NA NA 46/51


When I got my first HDTV I knew there was input lag. I could feel it especially in Geometry Wars. My friends thought I was a bit crazy but I knew the lag existed. Over time I got use to it so it didn't bother me as much. Still, it's nice to be able to measure it....sort of (there is still a good amount of assumptions/estimating going on). How sensitive you are to input lag really does depend on the person.

Bottom line for me is for every day gaming even standard mode is fine. For more serious gaming (online, or going for a leader board high score) then Game Mode really does make a difference.

Additional Research:
http://www.avsforum.com/avs-vb/showthread.php?t=1019543
http://www.avsforum.com/avs-vb/showthread.php?t=558125

UPDATE: 12/06/08
- So I picked up a rock band 2 guitar for 360 and it has audio/video sensors to automatically calibrate for lag.
Sharp LC-52d64u: 1080p, hdmi, game mode off: 30ms (multiple tries, results were very consistent and repeatable)
samsung LN46a630: 1080p, vga: 45ms (though something was wrong because I couldn't get a consistent reading. I had values as low as 20's and high as 80's so I don't trust this number. I tried everything: turned lights on, lights off, different distances/angles, backlight levels, etc)

27 comments:

Anonymous said...

Thats cool... but did you really just spend that much time comparing delays in ms on your tvs?

Zyjal said...

Great stuff, Thanks for taking the time to do it! I am considering an a630 myself and was worried about lag. Looks like with game mode, the samsung is pretty competitive though.

If it really bothers me on some of the old 480i games, I suppose I can go plug into the CRT!

ARogan said...

Glad you found it helpful. I don't play much 480i stuff these days but once in a while if you are in the mood for some retro stuff, it's good to know game mode helps out a lot.

Anonymous said...

Hey Arogan, thanx for taing your time for this info, it is really appreciated. My question is: Do you know what is the best way to reduce input lag on the LN46A650, is it HDMI2 on PC mode, or game mode ?

ARogan said...

My best guess would be game mode. From my tests that seem to do more good than pc mode on hdmi 2.

Anonymous said...

But on the 650 ?

ARogan said...

No idea on the 650 since well I don't own one. Though most people think the 650 and 630 are pretty close to identical. Take it for what its worth.

Anonymous said...

hrm so it seems the HDMI rename trick hurts lag time by almost double... intresting

Anonymous said...

Great article, but do you know what the lag would be with a Full HD source, would it be at like negligible levels?

And what is the better brand if I were searching for a gaming TV, and why?

Anonymous said...

i was looking at the ln46a650..waiting for it to hit $1300. instead, when I went into my local bestbuy, I found a Pioneer Kuro PDP-5020FD open box for $1500. Spent the extra cash and all I can say now is WOW. NO lag sensed playing halo. Plugged in GH Aerosmith and consistently scored <20ms--usually 0 or very close to 0. Don't have RB2 to do their automated test but I definitely very highly recommend it.

PS I used game mode, but it looks just as amazing.

JT said...

I'm deciding if i'm going to buy the Sharp LC-52d64u tonight.

I'm a BIG Rock Band/Guitar Hero fan, but I wanted to know what the lag is with game mode ON. You ran an auto-calibration, but with game mode Off.

Can you make a quick calibration run w/the LC-52d64u, Rock Band 2 guitar, and Game mode on?

Preemptive Thanks!

Anonymous said...

Here is some testing / discussion / info for the Samsung LNXXA650

http://www.avsforum.com/avs-vb/showthread.php?t=1110472

id0l said...

Youre HDMI2/DVI + PC Mode testing is flawed. You need to feed the TV a 1920x1080x60hz signal for PC Mode to work. Any other resolution or frequency will cause game mode to not function.

Research has proven that HDMI2/DVI + PC Mode has proven the best results (least input lag) of all, even better than game mode. The only thing that is virtually lagless is VGA at near 0ms, followed by HDMI2/DVI + PC Mode at 6-15ms, then Game Mode at 25-35ms.

Any mode besides "HDMI2/DVI + PC mode" or VGA will introduce some sort of image processing, done by the TV, and that is why you get lag. Game mode has the least processing, but still uses edge enhancement, sharpness, and a range of other settings to give it that "Pop" (I think it's way ugly, and not at all true to the source), but less enhancements than other modes. Hence a balance of around 15-25 ms lag.

If you use you XBOX360 or PS3 in HDMI2/DVI + PC Mode, make sure you make the following changes:

XBOX 360 - HDMI Black Level: Extended, Source: RGB

PS3: - Video Settings: RGB Full

In PC Mode, the TV is now looking for and displaying the PC color range, which is 0-255 as opposed to TV standard of 16-235. The black level is forced to "normal" in PC mode and you must make the appropriate black level and color changes to your XBOX360 and PS3 for it to look correct.

id0l said...

Type in my last comment.

Should read:

"Any other resolution or frequency will cause PC mode to not function."

Anonymous said...

These numbers are a lot different than what i've personally found with the same set (LN46a630)

Game mode and non-game mode over component in 1080p produced the same 90-100ms of lag in RB2 every time, and this is with an auto calibration. It's backed up by several attempts to manually calibrate it, with a second opinion, all within 10ms of eachother. Completely unplayable outside of VGA mode, and VGA mode just plain looks bad.

The A630 is great for movies/TV and produces a wonderful image once it's fully calibrated. However, it is practically useless for gaming.

Anonymous said...

i think you should re-take all your pictures with a faster shutter speed because you can't pull data out from blurry pictures/numbers.

you're just making assumptions about how many frames it's behind based on what?

re-take the shots while a millisecond stopwatch is running and then you can just compare the numbers on the screens.

Anonymous said...

.... the idea is to freeze the numbers

Anonymous said...

Where can I find the input lag software with the green text that you use here?

Anonymous said...

Ohh sorry too fast. Found it here:
http://www.flatpanelshd.com/focus.php?subaction=showfull&id=1229335064

tim said...
This comment has been removed by the author.
tim said...

What audio lag did your TVs get when calibrated with Rock Band 2?

ARogan said...

tim, I don't use TV speakers. All my hdtv's are hooked up to 5.1 surround systems. Anyways, my onky txsr705 has around 150ms.

KVM Switches said...

I have read this great article about LCD HDTV input Lag test.
It's very useful and informative for me.
Thanks for posting this awesome article.

TVs said...

There are now ways of dealing with this lag so that it isnt noticeable from certain input devices

Decorative Concrete said...

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custom essay writer said...

didn't see nothing bad in Hi0Def TV. Only positive - quality is better, it's not so bad for health as old TV. As whole - good

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