Thanks for joining the forum!Four Wude wrote:Hello everyone, I run Display Lag and I wanted to gather your feedback. As of right now I've personally graded 148 displays and continue to grade as many as I can. I received an e-mail from marqs and I figured I'd chime into this community.
First, I'd like to note something about that Sony you guys are having issues with. Here in the US, my friend has a Sony TV from the same/similar model line as the one that's causing issues for you guys, and it exhibited the same behavior that you're experiencing with 0ms on the middle bar. It was the only HDTV I have graded (even among Sony's 2012 and 2013 models) that caused such an issue. I'm not sure what is causing it, therefore I chose not to report the display in my database as it seemed sketchy. So don't be too quick to think your tester is broken, for some reason that specific Sony model line acts weird with the tester.
I'd also like to gather opinions on the differences between the top, middle, and bottom bars. As some of you know, all ratings in my database are calculated from the bottom bar. I decided to adopt the same standard that AVForums use as it was the first authority website to use the Lag Tester in their reviews; they use the bottom bar. I was also recommended by John Beeson (Leo Bodnar's associate) to use the highest ratings I can get as a reference (which are typically found on the bottom bar).
There has been some discussion about using the top bar instead of the bottom, based on what marqs emailed me. Unfortunately, I only started recording all 3 ratings on the last 55 displays inserted into my database (which leaves a good 93 displays with only bottom bar results).
Please advise, and thanks for the support! I don't intend to mislead anyone and want everyone to be on the same page. If you have any questions, feel free to ask.
- Adeel
We've been trying to figure out an accurate way of measuring the latency here. I think we should ask Leo himself about when exactly the counter is started, which would hopefully clear some confusion. If the counter was really started after the complete frame (showing the bars) was sent to display, it would mean that almost all flat displays (except the previously mentioned Sonys) would have at least 1 frame of latency. I'm not ruling that possibilty out yet, but I find it hard to believe (and which would be quite depressing if true )
Yeah, the refresh logic of flat panels is an interesting topic in itself.Fudoh wrote:I would be really interested in understanding the technical background, why some displays would show differences in the readings when using different bars, while other displays will give the same results no matter which bar is used.
Good point. However, we all probably agree that this happens on a CRT where the input controls the ray directly, yet there is no visible tearing - right? How I see this is possible, is that the tearing between 2 consecutive scanlines only lasts the draw duration of one scanline (~33us at 480p@60Hz), after which it moves one scanline down. In contrast, tearing in e.g. a non-vsynced PC game lasts the duration of the whole frame. It'd great if someone with a high-speed camera could verify all this. I also thought earlier that all flat panels would draw the frame instantly, but the various results indicate that it's not always this way (which is a good thing - at least from latency perspective).Fudoh wrote:I can understand a certain difference (in the single ms range). That's just the time the display needs to draw the whole screen, so you get subtle brightness differences which show in the readings, but how can a display show a whole frame of difference between the top and bottom bar ? Imagine the input signal not being a static screen like it is now, but a horizontally scrolling game. A time gap of up to 16ms between the top and the bottom of the screen would cause serious tearing - to a degree where the display would not be useable anymore for any kind of gaming...