Support for VK_EXT_present_timing in the Vulkan backend?

[c-ostwald]

VK_EXT_present_timing was recently merged into the Vulkan 1.4.335 specification and appears to already be supported, or soon supported, by several drivers.

I'm wondering whether there are any plans to make use of this in mpv's Vulkan backend.
From the Vulkan documentation:

Multimedia applications also typically require accurate frame timing in order to closely match the content’s expected frame rate and synchronize presentation operations with audio output.

According to the Khronos proposal and related blog posts, VK_EXT_present_timing provides a platform-independent way for applications to specify time-based presentation, allowing the compositor/driver to schedule frame presentation more precisely.

Since mpv already relies heavily on accurate frame pacing and A/V synchronization, this extension seems potentially relevant for improving presentation timing without relying on platform-specific mechanisms.

Would this provide any practical benefit for mpv, or is the current presentation timing approach already sufficient?

[nokia8801]

This would be great to have indeed.

But as far as I know, mpv with these settings already present in perfect frame pacing and synchronization if the compositor supports the required stuff (like Mutter).

gpu-api=vulkan
gpu-context=waylandvk
video-sync=display-resample
vulkan-swap-mode=fifo
wayland-present=yes
wayland-internal-vsync=no

The manual has more info on why these are the case. For example, Mutter supports both the FIFO protocol and v2 of presentation time protocol, so you can disable mpv's internal vsync with no (auto sometimes doesn't work for me) and with video-sync=display-resample you get perfect frame pacing, at least on my system.

But I'm hoping VK_EXT_present_timing would further improve this or be much better.

Also, Mesa has VK_EXT_present_timing in Mesa since 26.1 for Wayland, and will have support for X11/XWayland with Mesa 26.2.

https://www.phoronix.com/news/Mesa-26.2-X11-Present-Timing

[GrabbenD]

with video-sync=display-resample you get perfect frame pacing

Are there any recommended methods to measure this?

[nokia8801]

with video-sync=display-resample you get perfect frame pacing

Are there any recommended methods to measure this?

Ctrl+I should give you an idea. There should be no dropped frames.

But I have a 240Hz monitor so VSync Ratio is always an even number whether I'm watching 24, 30, 60 or 120Hz content. That could be an outlier for my setup.

[roberth1990]

This gave me the smoothes playback on my system:

swapchain-depth=1
vulkan-swap-mode=mailbox
wayland-internal-vsync=yes
video-sync=display-resample
interpolation=yes
tscale=sphinx
tscale-blur=0.6991556596428412
tscale-radius=1.0

With KDE Plasma and nvidia propietary driver.