# FAQ

## All Platforms

- My playback is too slow. How can I improve it?

  Check that you have:

  > - Window->Preferences

  >   - OpenGL

  >     Color Buffers’ Accuracy set to Automatic (preferred) or Fast.

  >   - Thumbnails

  >     Preview Thumbnails Above Timeline off.

  >   - Playback

  >     Auto Hide Pixel Bar checked or optionally hide the pixel bar or set the UI to presentation mode.

  > - Panel->Settings

  >   - Cache Gigabytes

  >     Set to 4GB at least (the default is half your memory)

  >   - FFmpeg Color Precision

  >     If you are playing a YUV420_P8 video with Color Space “undefined” this setting will provide a more accurate color conversion, but it can make the reading of the movie slow.

## Linux

### All protocols

- Playback of screen captures don’t play at their actual speed.

  Sadly, this is a limitation of mrv2. Screen captures such as those created by Ubuntu may rely on Variable Frame Rates (VFR), meaning that the speed changes between each frame of the video. mrv2 needs a constant frame rate throughout for playback, for seeking and for showing the timeline.

### X11

- I see some tearing of the video during playback. How can I fix it?

  This is likely an issue with your configuration of your graphics card. For NVidia graphic cards, you can fix it by:

  > - Edit /etc/X11/xorg.conf with sudo permissions.

  > - Go to the “Device” section of your NVIDIA graphics card.

  > - Add or modify:

  >       Option "TripleBuffer" "True"
  >       Option "SwapInterval" "1"

### Wayland

- My playback is too slow. How can I improve it?

  Check that you have:

  > - Help->About

  >   - Go to the HW tab.

  >     Check the GPU information and make sure that Vendor/Renderer is not Mesa, but the appropriate for your graphics card. For example:

  >     Vendor: NVIDIA Corporation Renderer: NVIDIA GeForce RTX 3080/PCIe/SSE2 Version: 4.6.0 NVIDIA 535.171.04

  >     Max. Texture Size:32768 x 32768

  >     If it is using Mesa, you may need to configure XWayland/Wayland correctly for your OS and graphics card. Or use mrv2 not on Wayland but on X11/Xorg.

  >     On Ubuntu 22.04.4 LTS, you should install the proprietary NVidia drivers 535 at least and do:

  >         sudo apt install libnvidia-egl-wayland1

  >     Note that NVidia’s EGL under Wayland under Jammy is buggy and may result on random stopping of the playback until you move the mouse. To fix it, install the deb package from Ubuntu Noble:

  >         https://www.ubuntuupdates.org/package/core/noble/main/base/libnvidia-egl-wayland1

  >     If you run into that, use XWayland or log in onto X11. To use XWayland, set:

  >         export FLTK_BACKEND=x11

- I get flickering positioning of Panels under Wayland.

  > This seems to be a bug in GNOME 48 (Mutter) when playing 4K at 60FPS.

- I get warnings when I run the pre-compiled mrv2 on the console under Wayland on a modern distro like Ubuntu 22.04.4 LTS, like:

      (mrv2:6869): GdkPixbuf-WARNING **: 09:23:50.243: Cannot open pixbuf loader module file '/usr/lib64/gdk-pixbuf-2.0/2.10.0/loaders.cache': No such file or directory

      This likely means that your installation is broken.
      Try running the command
      gdk-pixbuf-query-loaders > /usr/lib64/gdk-pixbuf-2.0/2.10.0/loaders.cache
      to make things work again for the time being.

      (mrv2:6869): Gtk-WARNING **: 09:23:50.244: Theme parsing error: gtk.css:1422:23: 'font-feature-settings' is not a valid property name

      (mrv2:6869): Gtk-WARNING **: 09:23:50.245: Theme parsing error: gtk.css:3308:25: 'font-feature-settings' is not a valid property name

      (mrv2:6869): Gtk-WARNING **: 09:23:50.246: Theme parsing error: gtk.css:3770:23: 'font-feature-settings' is not a valid property name

  Sadly, these cannot be avoided. You will need to re-compile from source on your target platform or use mrv2 under XWayland or under X11.

- While repositioning or rescaling floating panels under Wayland, I get clipping redraws of the floating panel.

  Unfortunately, this is a current limitation of FLTK 1.4.

- When I have a long floating panel, like the Media Information Panel, I can drag them out of the screen, and cannot repositiong them.

  You can use ALT + F7 to reposition it.

- Using drag and drop from Chrome or Chromium does not work on Wayland.

  This is because mrv2 runs under Wayland while Chrome runs under XWayland.

  There’s a good workaround, though, to work with Wayland: chromium can be made a Wayland client launching it as follows:

      chromium --ozone-platform-hint=wayland &

  With this, DnD from the chromium URL field to an FLTK Wayland client app works both with gnome/Mutter and KDE/Plasma.

  It’s possible to configure chromium so it runs as a Wayland client when possible and an X11 client otherwise:

      run chromium
      type chrome://flags/#ozone-platform-hint in the URL field
      change Preferred Ozone platform setting to Auto
      close and re-launch chromium which will run as a Wayland client.

  Note that Chrome’s Wayland support is currently very buggy.

## Windows

- After an install with file associations all icons appear with the mrv2 logo. How can I display the picture thumbnails once again?

  - It is a bug in Windows, but it can be worked around. You manually should select one file extension that you want thumbnails from and select:

        Open with->Choose another app

    Then select “Photos” from the menu and “Always”. This will restore the thumbnail, but it will remove the association to mrv2. To once again associate mrv2 to the file, go again to:

        Open with->Choose another app

    But this time select “mrv2 Media Player Latest” and “Always”. This will associate mrv2 back to the file, but leave the thumbnails. You will see a small icon of mrv2 on the right bottom corner of the thumbnail.