Samsung LN46C630 review: input lag, deinterlacing and upscaling using the piLagTesterPRO

This  "120hz" 1080p TV sold for around $900 in 2011.  It has very bad input lag. 

Overview/Image quality

I tested a TV that had damage to the panel so I couldn't do my standard image quality tests. 

It advertises itself as supporting 120hz, but this is really a motion smoothing option, and the TV can't accept a 120hz input signal - the fastest input it can sync to is 60 hz. But as we will see there is some truth to the 120hz designation, see below. It also supports 24hz mode for movies, properly displaying at 24hz with no dropped frames. 

It has all the standard inputs, including 4 HDMI, VGA, and 2 yPbPr.

Input Lag

This display has a game mode. I couldn't find any evidence that game mode was any faster in terms of input lag, but it did make one difference: it turns on the backlight flicker. This probably makes motion look a little smoother, though the set has "motion smoothing" features which might do the same outside game mode (motion smoothing is off in game mode). 

I used a piLagTesterPRO to measure input lag. This device sends a frame of video over HDMI and measures how long it takes to display it. 

Input Lag Test Results 

I report two kinds of values. 1st response measures how long it takes for the TV to start responding (I use a 5% change in display brightness). This overly optimistic value doesn't tell how long it takes to see anything useful, but matches what other reviewers call input lag. full response is a more realistic measure of lag, and requires the display to reach 80% of full brightness. This combines both input lag and response time, and is closer to what you would actually experience in a game.

This TV has two unusual features: it redraws the screen every 8ms (instead of 16ms), which is the sense with which it's a 120hz screen. That helps lag a little bit and supposedly improves motion smoothness if you fill in the implied motion between frames intelligently (I didn't test this). The other thing that's odd is it draws from the bottom of the screen up. Thus the first pixels painted on each frame are the bottom row:

Resolution1st (average)full response1st responsefull responsescan outresponse time

This seems like a REALLY dumb choice; since the HDMI signal is sent from top to bottom this means the TV can't possibly start processing the next frame until the entire thing is sent to the TV, implying an extra 16ms of lag. And indeed this TV has lots of lag. To be fair, given the motion smoothing algorithms that it's using to fake 120hz, it may have to wait until the entire frame is delivered before it can start processing anyway. Whether it's a bad design or a moot point, the TV has awful lag, even in game mode. 

It was fastest in native (1080p) mode, where it started drawing pixels 54ms after the frame was sent to the TV. It was noticeably slower in 720and 480p, taking about 18ms longer to start drawing. For a modern display to take that long to upscale is scandalous. I'm not sure it's exactly that, because the set also supports 960p and that's just as fast as 1080p. Whatever is going on, if you use this for gaming it had better not be retro gaming!

The only bright point is that deinterlacing (480i) is no slower than 480p. Not sure why that is; usually it means that bob deinterlacing is being used, but I couldn't tell because of the screen damage. There's so much delay in the TV that maybe there's plenty of time to deinterlace properly. Who knows. 

Response time was around 10ms. This was in game mode. Outside of game mode response time as a bit slower; around 13ms. So game mode does two things: smooth motion by flickering the backlight (many TVs do this and don't call it game mode) and speed up response time a little. I guess every little bit helps but with a TV this slow it doesn't add up to a very good package. 

Results compared to other displays

To allow quick comparison between many displays I've summarized the results across all the displays I've personally tested with the piLagTester Pro. For this set, since it draws from bottom to top, Min lag is the first response at the bottom of the screen; real lag is the full response at the top. For most sets it's the reverse, but think of it this way: min lag is when the screen starts drawing, real lag is when it finishes. Numbers in red denote average values that can vary by up to 8ms between power cycles. 

This list is sorted by real lag in the display's native mode. Thus, if the display supports higher than 60hz refresh rates it can get a boost in this table, and TVs that struggle outside of native resolution are not penalized. 

DisplayYear made (TV?)Native Resnative min lagnative real lag480i real lag480p real lag720p real lag1080p real lagnative response timenative scan out
Dell E198FPb20081024p2.720.439.035.05.0012.70
Vizio VO370M20101080p2.523.683.
AOC/Envision G19LWK2010900p3.131.239.538.738.437.815.5012.60
Dell E2211H20141080p3.033.634.734.534.133.815.0015.57
Panasonic TH-58PE75U2008720p28.
Dell 1907FPc20081024p3.034.035.934.815.0016.00
Corprit D157 (hdmi)20211080p3.134.534.934.834.633.916.2515.13
Samsung S27C23020141080p2.936.136.636.137.018.2514.97
Vizio E470VL (vga)20111080p22.
Dell U2410 (sRGB)20101080p20.542.862.445.
ACER AT326520121080p19.543.862.745.343.843.88.0016.27
RCA L40FHD4120101080p20.346.665.
Sony 40VL130 (game)20081080p22.847.366.349.047.347.39.0815.43
Polaroid FLM-373B2007720p28.
Philips 42PFL3603D/F720091080p29.
Emprex HD 32022007720p27.050.5126.
LG 42LC2D2006720p28.350.654.650.850.46.3015.95
GPX TDE3245W2016720p28.051.0102.
Sony KDL-46EX40020101080p28.
Toshiba 40L2200U20141080p30.
Vizio VO22L FHDTV10A2008720p28.
Sharp LC-C3234U2009720p33.064.683.666.664.615.0016.60
Toshiba 46L5200U20131080p55.
Sony 40S20L12007720p48.472.090.172.973.49.6014.00
Samsung LN46C63020121080p54.572.190.790.388.572.310.007.63
Samsung HP-T425420111080p69.775.794.
LG 47LW6500-UA20121080p66.680.7149.7149.081.780.92.2711.83
Vizio E470VL (hdmi)20111080p69.086.0128.

Note that sorting by real lag really helps this TV because it has the 8ms scan out.  Nonetheless, it's still near the bottom of the TVs I've tested.  Although I haven't looked at many smart TVs from the early/mid 2010s, they all have been poor performers. Dumb TVs may be a smarter choice for gaming...


This tv has bad lag. It's probably a fine choice for Movies, TV, Netflix, etc. 

If you do decide to get this for some reason, make sure it has a remote. In a fit of marketing buzzword compliance, it uses capacitive buttons on the set itself, making it nearly impossible to find the buttons and/or press them one at a time. 

Other models (to avoid)

I only tested input lag on the LN46C630, but I would expect that the LN40C630, LN55C630, and LN60C630 would perform the same, based on similarity of the model numbers and specs, just with different sized pixels.  Honestly, I'd just avoid all Samsung TVs from this era based on how poor this one behaved.  


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