Drawing mode very slow

[ianmccul]

Hi, just discovered pdfpc, its great! Only one small issue that makes it not so usable for me, the drawing mode with the pen tool is very slow to update, which makes using the pen (with either mouse or stylus via a wacom tablet) almost unusable. The laser pointer mouse is also slow to update for me but that is less important.

In fullscreen mode when drawing with the pen Xorg is pegged at 100% CPU usage, and pdfpc at about 30% (this is on a 16 core ryzen threadripper, the presentation monitor is 1920x1080, the presenter monitor is 4K).

Using windowed mode helps a bit, the pen is a bit more fluid (but not great). pdfpc is pegged at 100% CPU usage, and Xorg is using about 50%.

[fnevgeny]

You chose to ignore our request to provide important information when submitting an issue...

[ianmccul]

Sorry, I missed that - what information do you want?

[fnevgeny]

When you submit a new bug report, it's listed in the template.

[ianmccul]

Ok, I just found the bug report template.

Expected Behaviour

smooth drawing behaviour

Actual Behaviour

mouse position is slow to update

Steps to reproduce

1. start pdfpc
2. move mouse (either pointer or pen tool shows the same effec)

pdfpc version: pdfpc v4.3.4
Used Distribution (GTK version, vala version): ubuntu 20.04
Display Server (X/Wayland): X
HiDPI Setting (yes/no):not entirely sure what you mean, but I think no, all monitors are at 100%, no additional scaling

[fnevgeny]

The current version is 4.4.0, which includes this fix. Please give it a try.

[ianmccul]

I just tried pdfpc v4.4.0. That makes it smoother, but it is quite laggy. The output is smooth enough that it would be usable for drawing, but a bit disconcerting as it takes half a second or so for the output to catch up to where you are drawing.

I also had a small problem with the install, 4.4.0 from the source tarball. sudo make install appeared to work OK but pdfpc wasn't working, complaining 'No CSS file found'. After some investigating I discovered that the install had created the directories /usr/local/share/pixmaps and /usr/local/share/pixmaps/pdfpc with permission 700. chmod'ding these to 755 fixed the problem.

[fnevgeny]

That makes it smoother, but it is quite laggy

What is laggy - the drawing or even the motion of the pointer (without pressing the mouse button)? Same question about the pointer mode.

Also, try using the single screen mode (-S) - does it improve responsiveness?

install had created the directories /usr/local/share/pixmaps and /usr/local/share/pixmaps/pdfpc with permission 700

Strange. What is your umask?

[stettberger]

I also observed a slaggy-drawing problem with the current master version (11719ed). For me the problem is closely related to screengrabbing: As long as I use pdfpc without a screengrabber (e.g., BigBlueButton or Jitsi), everything is quite smooth. In the moment, when I start the screensharing/screengrabbing, it starts to get slaggy. The problem becomes more severe if I start to draw. However, the slaggy behavior sticks with me from there on.

I've recorded a screencast for you: https://youtu.be/ayos9PLazJY

The screencast of course triggers the behavior (simplescreenrecorder, xorg 7.7, Hidpi: no, single window mode). As you can see, the laserpointer severly lags behind the actual mouse pointer.

[fnevgeny]

@stettberger Thanks, it's impressive :). But I cannot reproduce it, also tried with simplescreenrecorder. I guess it might be related to video driver. Hmm, xorg 7.7 is pretty old - circa 2012, right? Are you using Linux or something else, which variant/version?

[stettberger]

... Ok. I was not smart enough to look at the correct place:

ii  xserver-xorg-core 2:1.20.9-2   amd64        Xorg X server - core server

This is the Debian unstable version.

[fnevgeny]

Well, nonetheless - what hardware do you have, in particular the video card?

[stettberger]

00:02.0 VGA compatible controller: Intel Corporation Skylake GT2 [HD Graphics 520] (rev 07)

This is a Thinkpad T460.

[fnevgeny]

Thinkpad L390 here, UHD Graphics 620. Cannot notice any slowdown...

[wentasah]

@fnevgeny pointed me to this issue. I don't experience slowdown, but I experience 100% CPU load. I did some profiling and the top three consumers are:

+   68.64%    68.63%  pdfpc  libpixman-1.so.0.38.4     [.] bits_image_fetch_separable_convolution_affine_none_a8r8g8b8
+    9.71%     9.71%  pdfpc  libpixman-1.so.0.38.4     [.] fast_composite_scaled_bilinear_sse2_8888_8888_none_OVER
     3.89%     3.89%  pdfpc  libpixman-1.so.0.38.4     [.] sse2_blt.part.0

To me, it looks like a lot of software rendering is happening.