[MathiasDevelopes]

What

[sceVideoOutAddPreVblankStartEvent](https://github.com/boykopovar/AnyPS5/blob/main/core/libs/prx/libSceVideoOut/src/Event.cpp) threw VideoOut: physical pre-vblank timing is not implemented. Planet Coaster (PPSA01736) registers a pre-vblank start event at startup and does not catch the exception, so it aborts:

[libc] unhandled exception 'St13runtime_error' thrown from ...
terminate called after throwing an instance of 'std::runtime_error'
FATAL: abort() (SIGABRT)

(what() is not printed on this path. A temporary print in __cxa_throw showed it as VideoOut: physical pre-vblank timing is not implemented.)

The event is now registered through the same registerVideoOutEvent path as the vblank event, so re-registration updates udata and sceVideoOutDeletePreVblankStartEvent (already implemented) removes it. In [VideoOutDriver::vblankEnd](https://github.com/boykopovar/AnyPS5/blob/main/core/libs/prx/libSceVideoOut/src/VideoOutDriver.cpp), each emulated vblank tick increments the port's preVblankStatus count, which already existed and was unused, and stamps its process time. It then triggers the pre-vblank start events with that count as data, just before the vblank events of the same tick.

How long before the vblank the console signals pre-vblank start is unknown. The vblank here is a host timer with no scanout, so the event fires at the vblank tick. This is recorded in [TechnicalDebt](https://github.com/boykopovar/AnyPS5/blob/main/docs/dev/TechnicalDebt.md) under unknown function info. [shadPS4](https://github.com/shadps4-emu/shadPS4/blob/0fe263a4760dfbfa973366890061749b4af0de97/src/core/libraries/videoout/video_out.h#L52) defines the event ID but neither registers nor triggers the event, so it gives no reference timing either.

Tested

Windows 11, MinGW-w64 15.2.0, RTX 3060.

• video_out_flip_tests controls: after the existing vblank checks, the test subscribes a pre-vblank start event with its own udata and waits for a vblank. It checks that both a pre-vblank start and a vblank event are delivered and that the pre-vblank event carries its udata, then unsubscribes. Without the change, it fails with VideoOut: physical pre-vblank timing is not implemented.
• The present and backtoback modes still pass. video_out_flip_tests opens a real window and is in KNOWN_UNRUN, so I ran these modes by hand.
• Full ctest suite: 505/505 passed. tools/check_conventions.py --base origin/main passes.
• PPSA01736: with the change, the title gets past the registration and goes on to render its intro. It needs other fixes to get that far: fix(relinker): relink the modules that found needed modules need #1782, fix(libSceHttp): sceHttpWaitRequest reports no ready requests #1775, feat(libkernel): open /dev/random and /dev/urandom for reading #1777, fix(agc): defer shaders that cannot be prepared at registration to their first use #1836, feat(libkernel): implement mlock and munlock #1673 and some local commits.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed in TechnicalDebt
• No notes, investigation .md files or images added to the repository
• New third-party code is a submodule built from source (none added)
• Generic behaviour, not specific to one title
• Depends on: none
• AI-assisted: yes

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