Run G_MESSAGES_DEBUG=all gnome-mpv <your-video-file>. Let the video play for a few seconds, then press Ctrl+C and post the output here.

After that, run mpv --length=3 -v <your-video-file> and post its output here as well.

gnome-mpv.txt
mpv.txt

Does setting --vo=vdpau solve the issue?

When I try to start gnome-mpv --vo=vdpau it says Unknown option --vo=vdpau.
Putting vo=vdpau into my mpv.conf doesn't fix it.

When I try to start gnome-mpv --vo=vdpau it says Unknown option --vo=vdpau.

You need to put the option in the textbox labeled Extra MPV options: in the preferences dialog (press Ctrl+p to open).

Still the same tearing as before.

Can you try playing a video fullscreen with this and see if you still get tearing? It's mpv's official client API example code I modified to support fullscreen mode. Compile by running qmake && make. You can toggle fullscreen mode by pressing F11. If you still get tearing with this, then the issue is probably related to mpv's client API support.

I tested it on the qtexample and couldn't find any tearing.

When I uncheck "Enable client-side decorations" and restart gnome-mpv I can't see any tearing. I guess I should have tried this sooner.
Also for this I found a relaiable way to reproduce the tearing. I noticed it doesn't always happen, sometimes I had to let it play a file for a while and seek before it started.
These are the steps that always produce tearing for me:

1. Start gnome-mpv
2. Press F11 to switch to full screen
3. Press Ctrl+o to open up the file
4. Press Ctrl+o again and open up the same file again
   After opening the file a second time, tearing will be visible. If the file is only opened once and played normally for a few seconds, I couldn't see any tearing.

Test file: (zipped so that I can upload it here)
test.zip

I can reproduce the tearing now.

I found that mpv does this when it's attached (using the --wid option) to any window that uses CSD, so the tearing is unlikely to be caused by a bug in gnome-mpv. I can reproduce the tearing with mpv using the steps below.

1. Open any application that has fullscreen mode and uses CSD, eg. Evince. If you use Evince, you'll need to open a document with it before it'll let you switch to fullscreen mode.
2. Run the following command and click the Evince window to attach mpv to it: mpv your-video-file.webm --wid=$(xwininfo | grep -oP '(?<=Window id: )[^ ]+')
3. Switch to fullscreen mode and wait a bit. You should be able to see some tearing after a few seconds.

That's not a mpv problem, rather an issue with either your compositor or the nvidia drivers. (With nvidia drivers, I can get good behavior only when setting it to maximum performance in general anyway - maybe that applies here too.)

Given how this won't work at all under Wayland, it might be a good idea to add support for opengl-cb embedding.

Given how this won't work at all under Wayland, it might be a good idea to add support for opengl-cb embedding.

opengl-cb is already used on Wayland.

But not on X? Any reason for that?

But not on X? Any reason for that?

It will use opengl-cb on X if the user explicitly sets vo=opengl-cb. It's not the default because gnome-mpv uses GtkGLArea to display video frames, which doesn't work for some users since it requires at least OpenGL 3.2.

since it requires at least OpenGL 3.2

That's really odd that it would require that...

Based on this, it requires core profiles from OpenGL 3.2+. Since gtk 3.20, it also supports legacy GL 3.0 profiles, but some users are still on older OpenGL versions.

For what little GL usage they have, there really isn't an excuse not to support GL 2.1 + FBO extensions. But whatever.

open gnome-mpv - press CTRL+P - Unmark "Enable client-side decoration"(its a first option.my english is not good^_^)its work on me

Are there any other workarounds besides disabling CSD in gnome-mpv?

Are there any other workarounds besides disabling CSD in gnome-mpv?

You can also use Wayland.

You can also use Wayland.

Oh god, that is even worse XD

I don't know Gnome well enough, but what about forwarding this issue to the CSD/Gtk devs?

@Esokrates You need actionable information first. Something smaller to reproduce than "Use libmpv to render an entire video".

I have found a workaround by installing this gnome-shell extension (works on 3.32):
https://github.com/kazysmaster/gnome-shell-extension-disable-unredirect
It seems to be a known problem since workarounds like this one apparently exist for a while.

Unchecking "Enable client-side decorations" doesn't seem to fix the issue anymore. Here is how my tearing appears:

1. Open a video with Celluloid
2. Double-click the player to go full screen
3. Move the mouse to show controls --> The tearing is visible. As the controls (and the csd) is hidden, the tearing disappears, but when I move the mouse again, the tearing appears.

To stop the tearing, I had to go to Preferences>Miscellaneous, and put --vo=opengl-cb in the Extra MPV options box, which is essentially the fix for #380 (Crash with "Use floating controls").

Test video

Additional Info:
Celluloid 0.18 (from universe)
OS: Ubuntu 20.04
Graphics: Mesa Intel (nouveau for nvidia)
Gnome 3.36.1

Opposite Experience for me:

Enabling vo=opengl-cb just made my issue worse.

Reproduce:

1. Open a video with Celluloid (only tested with 1080p .mkv so far.)
2. Double-click the player to go full screen
3. Tearing is constantly visible
   To stop the tearing, I simply had to disable CSD.

Additional Info:
Celluloid 0.20 (Flathub)
OS: Fedora 32 GNOME
Graphics: Mesa X.org AMD Radeon RX 5600 XT (NAVI10, DRM 3.38.0, 5.8.13-200.fc32.x86_64, LLVM 10.0.1) Mesa 20.1.9
Gnome: 3.36.6 on X11

Tomorrow I'm probably going to get a full bugzilla report to submit to GNOME and/or Mesa depending on what I can figure out.

This is still reproducible on Celluloid 0.22.

• OS: Fedora 35
• Desktop environment: GNOME 41.6
• Windowing system: X11
• Graphics card: AMD Radeon RX 6800 XT
• Graphics library: Mesa 21.3.9

Here's a relevant bug report on GNOME's bug tracker.