Does using --swapchain-depth=1 disable the vsync queue?

[norinoriko]

I'm slightly confused by the description of this option in the manual.
https://mpv.io/manual/master/#options-swapchain-depth
Does setting --swapchain-depth to 1 mean:

1. mpv will only have a max presentation latency of 1 frame,

or

2. There will be no vsync queue at all, and all of the rendered frames will be presented as-is at a consistent rate.

I'm assuming it's the latter since setting swapchain-depth to 0 is impossible, but I just wanted to make sure.