Dear Maintainer, I am using Openbox (in Debian Bullseye testing) where, as you know, some kind of window compositor is obligatory. So, as advised, I first turned to Compton, now Picom, and it worked fine regarding the handling of most of the software windows. But when trying to watch videos, with MPV in my case, there is really awful video tearing, about 20-25% of the image, a little above the middle of it. I first thought it was a problem with Compton/Picom, but the description says they are all based on Xcompmgr. So I tried to run xcompmgr (in OB autostart) without and with options (xcompmgr -c -t-5 -l-5 -r4.2 -o.55 &). I came to exactly the same result. Always the same tearing. As a result, I removed Compton/Picom, commented #xcompmgr, wrongly turned to Mutter, and finally gave up all these. And still there is a minimal window handling which I discovered was due to feh, the background choose, whose dependencies bring a minimal window handling that looks much like the one we have in Jwm (Joe's Window Manager). So I stick up to Feh for a minimal "pseudo- compositor" and the videos are perfect, the video image is even more precise. Only the software windows look worse when you handle/move them. My install is quite regular, testing, no foreign debs, no previous (debian) debs nor experimental debs. I make daily updates (at least in testing). My CPU is amd64 E1, Radeon graphics, 2014 laptop 6Go RAM. A few debian non-free firmware are necessary to make it work (much developer doc) but no non- recommended debs like radeontool. What moved me to report this bug is that everything worked fine with Compton, and so Xcompmgr 1.1.7-1, in Openbox for Debian 10 stable. The debian 10 XFCE special compositor gave some bad tearing too, so I turned it off or used Compton in XFCE for watching videos and compositing windows. I used tearing test videos like https://youtu.be/gmHaa5pvpVc (4k vsync test 60fps) https://youtu.be/9hIRq5HTh5s (vsync tearing test) https://youtu.be/MfL_JkcEFbE (tearing screen test) Cordially, Pascal.
Dear Maintainer, A few more informations about this problem of tearing : - When I make multiple screenshots of the video (with tearing) going on, the image on all the screenshots is perfect. I made this test with the video https://youtu.be/gmHaa5pvpVc (4k vsync test 60fps) at WEBM 720p in MPV of course, not a web-browser. I made tests with that video too at 720p 1080p 30fps & 60fps. - I use MPV because it is the quicker and most efficient & useful for watching videos, e.g. coupled with SMPlayer. - When I watch the video above mentioned at 720p in VLC or Totem, without xcompmgr (when there is no tearing in MPV), some tearing does still appear, especially at the beginning of the video (when CPU workload is heavier). Remark that on my PC there is often slight video tearing in Firefox in all cases, with all desktops (CPU overload). - I bought my laptop in 2014, it is exactly a AMD E1-2100 APU with Radeon HD Graphics, 1600x900, 2xCPU 1GHz. It can't read up to 1080p videos, it does not produce tearing (in Gnome, Budgie or even Openbox) but sometimes skips images in some 1080p WEBM videos when they are quite fluid in the same MP4 video and ~same-sized. A 4K video is quite unthinkable in all cases (and useless on a PC). I didn't buy it for watching videos nor for image work (like Blender) anyway. All this to say that my PC is maybe too old & slow. But xcompmgr 1.1.7-1 worked quite finely. Maybe something delays the execution of xcompmgr that goes unnoticed on a quick computer (just an idea), like it happens with bloated software, or Java-based software that would take minutes to launch on my PC (if I had not given up using Java). So I hope this problem is just mine, but please check and maybe report upstream if necessary, you are more qualified than me to do that. Cordially, Pascal.
Dear Maintainer, I generally never do that, but as installing xcompmgr calls absolutely no dependencies (at least in my case), I just tried to install (via dpkg) version 1.1.7-1 instead of 1.1.8-1 (via apt). It doesn't change anything, I get exactly the same video tearing with v1.1.7-1. Conclusion : my bug report is not so relevant. So please remove it or keep it as information and search of what is wrong elsewhere, in the dependencies which may also have other dependencies. With all my deepest apologies, Cordially, Pascal.