cursor lag... why?

[robcat2075]

Here's a brief clip of me waving my Cintiq pen around the screen. You'll see that the cursor is always about 5-6 video frames behind the position of the pen.

 

cursorlag.mov

 

I'm wondering why it should ever be more than one screen refresh behind. Consider that the screen is refreshed at 60 fps. On a 2.5 GHz computer that means there 41.6 million clock cycles between every screen refresh.

 

I would think that on an otherwise untasked computer it should be possible to read the position of the pen and update the cursor on the screen in less than 41 million clock cycles and yet there seems to be a pipeline of delay built into the process.

 

 

[Fuchur]

You can not really define it that way... there is very likely much more to it like write-speed of RAM, Cache, driver processing, other processes running on your system, reading the RAM, etc.

Anyway... it should not be noticeable too much... I am not sure if there is something not okay with your PC... 5-6 frames is a little bit too much... 2 frames would be normal (just guessing).

 

See you

*Fuchur*

[robcat2075]

It can't be other processes, the most the CPU ever gets up to while I'm waving the pen around is about 1%. It's 99% idle even while it's reading the pen continuously.

 

They X and Y position of the pen is probably two bytes apiece plus another two bytes of pressure value. Reading and writing 6 bytes to RAM... that can't possibly be a RAM speed problem.

 

The image of the cursor, if it's even 16 x 16 pixels would only be 768 bytes of display ram to be moving around. That can't be a burden either.

 

If those were actually pushing the limits of the computer then we'd expect the computer to be freezing every time the pen moved but it doesn't.

[pixelplucker]

Is it the Cintiq doing that?

Do you have a drawing tablet you could test with. I have 0 lag on mine but it is a newer model.

Some programs are laggy, Illustrator and Adobe products in general don't really take advantage of hardware but your cursor seems slow in general without anything running.

 

I even have my old Intuos hooked to a celeron laptop and that seems quicker. The celeron is only 1.6 gzh with 8 gb of mem on it.

If it is a background process then as that program runs it may lag the cursor but wouldn't necessarily be sluggish all the time and you would notice a speed difference as you drag.

 

Good example of that is if you have automatic updates on (part of Microsoft's way of being a Nanny for Nitwits) and if you were drawing the cursor may pause as you work.

 

You could look at your system monitor and see if the cpu is doing anything when the machine is idle.

 

A slow overheated cpu may cause the laggy cursor too. You may have the equivalent of a full size house cat trapped in the heat sink and fans.

Also when is the last time you defragged your hard drive?

 

Just tossing some ideas out there.

[robcat2075]

-I'll note that when the cursor is controlled by the mouse it is absolutely responsive.

 

-If over heating were the problem this computer would be at a standstill since I frequently do far more intensive things than move the cursor with pen. It's just not plausible. And again... the CPU is 99% idle while I'm moving the pen.

 

-And there's no hard drive access involved in the moving of a cursor from one frame redraw to the next. That could never work.

[Fuchur]

No, if it is anything if would be a Cache or at most RAM-write... harddrive would be unusual.

See you

*Fuchur*

[pixelplucker]

Good point with the mouse moving the cursor.

Maybe it's the Wacom driver? Wacom is famous for making crappy drivers and outstanding hardware.

[NancyGormezano]

I don't know which OS you are using, nor which Cintiq, nor which driver, nor what settings ...and I will assume you already googled for a solution?...

 

but just in case, because I am curious, I googled "cursor lag on cintiq" and came up with this youtube video. Yes it's for wacom tablets, but it might provide some insight as to which settings might also be worrisome for cintiq

 

 

and perhaps

 

 

AND here is thread on wacom site for lag pen delay for cintiq (21) from 2010

 

http://forum.wacom.eu/viewtopic.php?f=3&t=4927

[robcat2075]

I have a new theory.... the driver is averaging together previous position readings over some small time frame, like a fifth of a second.

 

Possibly they do this to mask some inherent jitter in the reading of the pen location but it means the cursor will always be at some average of where the pen has been in the immediate past and not where the pen is NOW unless the pen has been stationary long enough for all the samples to be in the same spot.

 

That would explain why the cursor slows-in to position even if I stop the pen suddenly.

 

That theory holds up until I draw in a tight circle. The average position of a circle would be the center but the cursor follows my circular path no matter how fast I draw.

 

FILE0271.MOV

 

So it's more complicated than just averaging the position but I think there's something like that going on.

[robcat2075]

I don't know which OS you are using, nor which Cintiq, nor which driver, nor what settings ...

 

I hadn't found those videos yet, thanks. I have some of those setting available but not all. Changing the ones I had didn't make any visible difference.

 

The forum thread eventually gets to someone quoting a Cintiq support person as saying that the lag is normal, so i guess I'm stuck with it.

[NancyGormezano]

I have a new theory.... the driver is averaging together previous position readings over some small time frame, like a fifth of a second.

 

...

So it's more complicated than just averaging the position but I think there's something like that going on.

If anything, I would guess it's either interpolating or more likely extrapolating the position...but perhaps the interrupt handler for the pen could be a lower priority task? and/or the graphics driver for the cintiq display could be the cause for lag, ie output to display is lagging, not the input handler of pen position.

[robcat2075]

I would presume that when the CPU is ticking along at 99% unused there is no task that is not getting serviced in proper time. There is just too much excess capacity available for anything to be getting put on hold.

[pixelplucker]

Whats the CPU clock speed?

Mines not extremely quick it's just a 2.66 but I have a larger monitor and I don't have any lag on the cursor with mouse or pen. I had pen & touch options on at one time but turned them off because they screwed me up especially flicks but the settings didn't seem to make a difference.

 

I can't say it's the Cintiq because I have tablets that are much older and don't have that issue even on slower machines and other than that the Cintiq is just a monitor behind a tablet surface.

 

Does your Cintiq connect via USB? Did you try unplugging all other USB devices to see if that does the trick? Maybe another device is hammering away on the USB controller slowing the input refresh.

[NancyGormezano]

here's some more food for thought about Cintiqs (again - not sure of your model, but if I recall, it was an old one gotten off ebay some time ago).

 

The following was excerpted from article located at http://www.studiodaily.com/2012/05/review-wacom-cintiq-24hd/

 

Dealing with Lag and Calibration Wacom products are always top-notch in quality and performance, but top-notch does not mean perfect. A persistent problem with Cintqs (some might argue with Intuos tablets as well) is lag. Lag occurs when the stroke being drawn lags behind the pen tip. This usually happens when working with very large files or complex brushes. Unlike a mouse the pen is transmitting vast amounts of data in real time to the processors. When the data transmitted exceeds the processors capability, lag occurs. Lag can be reduced or avoided by increasing RAM and working with a good graphics card.

 

While lag is a processing issue, having to calibrate for viewing angle and parallax are physical issues. Because the display on Cintiqs can be positioned at varying angles, the viewing perspective changes, resulting in the illusion that the pen tip does not match the on-screen cursor. On the other hand, parallax is caused by the physical distance (a few millimeters) between the display and the pen tip that results from the glass screen between them. To correct for viewing angle and parallax, it's essential to calibrate the Cintiq as needed. Though this many seem like a chore, you can take of it easily and quickly with the Wacom tablet utility

 

Edited December 1, 2014 by NancyGormezano

[robcat2075]

That guy may be an artist but he hasn't thought through the numbers.

This usually happens when working with very large files or complex brushes.

 

A large brush in a paint program will lag with a mouse, even when a pen is not being used. That lag is not created by the pen.

 

 

 

But my test case is just the pen moving the cursor on the desktop where the overhead of a brush is nearly zero.

 

Unlike a mouse the pen is transmitting vast amounts of data in real time to the processors. When the data transmitted exceeds the processors capability, lag occurs.

 

 

 

There is no way that the data from a pen is overwhelming a processor. It's impossible.

 

First I'd note that the pen is being read continuously (145 times per second according to that Wacom thread), it doesn't produce more data because it moves or moves fast.

 

Second, the pen data is microscopic... An X position, a Y position and a pressure reading, each of which is a two byte value at most. Lets presume that somehow those six bytes gets ballooned to 10 times that when they are wrapped up and ID'd to be sent across the USB.

 

That would give us a data rate of 69,600 bits per second which is 0.0145% of the 480 Megabits per second capacity of a USB connection.

 

The reality is probably way less than that because i can't imagine a 10x inflation of the data just to go across USB.

 

There is just no way that the pen data rate is a problem. If it were, a computer would freeze the moment we plugged in a Cintiq because that is data it produces all the time.

[pixelplucker]

I have a really stupid question...

Did your Cintiq Always lag or is this just something recent?

[robcat2075]

The lag has always been as it is now.

[pixelplucker]

Do you have another computer or laptop to test it on? See if it is the Cintiq or if it happens to be just with that system.

 

I see the lag, not nearly anything like the Surface Pro 3 though.