feat(libSceVideoOut): deliver pre-vblank start events

core/libs/prx/libSceVideoOut/src/Event.cpp

@@ -120,10 +120,7 @@ int APS5_VABI sceVideoOutAddVblankEvent(KernelEqueue eq, int handle, void* udata
 }
 
 int APS5_VABI sceVideoOutAddPreVblankStartEvent(KernelEqueue eq, int handle, void* udata) try {
-    static_cast<void>(eq);
-    static_cast<void>(udata);
-    VideoOutDriver::Get().GetConfig(handle);
-    throw std::runtime_error("VideoOut: physical pre-vblank timing is not implemented");
+    return registerVideoOutEvent(handle, eq, VIDEO_OUT_EVENT_PRE_VBLANK_START, udata);
 } catch (const ProcessShutdown&) {
     LibcAwaitExit_nid_postfix();
 }

core/libs/prx/libSceVideoOut/src/VideoOutDriver.cpp

@@ -406,6 +406,10 @@ void VideoOutDriver::vblankEnd() {
         std::lock_guard cfgLock(cfg->mutex);
         if (!cfg->opened || cfg->failure) continue;
         require(cfg->vblankStatus.count != std::numeric_limits<uint64_t>::max(), "vblank counter overflow");
+        ++cfg->preVblankStatus.count;
+        cfg->preVblankStatus.processTime = sceKernelGetProcessTime();
+        cfg->preVblankStatus.processTimeCounter = sceKernelGetProcessTimeCounter();
+        triggerEvents(*cfg, VIDEO_OUT_EVENT_PRE_VBLANK_START, reinterpret_cast<void*>(cfg->preVblankStatus.count));
         ++cfg->vblankStatus.count;
         cfg->vblankStatus.processTime = sceKernelGetProcessTime();
         cfg->vblankStatus.processTimeCounter = sceKernelGetProcessTimeCounter();

core/libs/prx/libSceVideoOut/tests/Flip.cpp

@@ -258,6 +258,13 @@ void testControls() {
     }
     check(sceVideoOutWaitVblank(handle) == 0, "vblank wait failed");
     check(owner->GetTriggeredEvents(&event, 1) == 1 && event.udata == &settings && sceVideoOutGetEventId(&event) == VIDEO_OUT_EVENT_VBLANK, "vblank event or updated user data missing");
+    check(sceVideoOutAddPreVblankStartEvent(queue, handle, &mode) == 0, "pre-vblank subscription failed");
+    check(sceVideoOutWaitVblank(handle) == 0, "vblank wait failed");
+    KernelEvent events[2]{};
+    check(owner->GetTriggeredEvents(events, 2) == 2, "pre-vblank or vblank event missing");
+    const auto& preVblank = sceVideoOutGetEventId(&events[0]) == VIDEO_OUT_EVENT_PRE_VBLANK_START ? events[0] : events[1];
+    check(sceVideoOutGetEventId(&preVblank) == VIDEO_OUT_EVENT_PRE_VBLANK_START && preVblank.udata == &mode, "pre-vblank event missing");
+    check(sceVideoOutDeletePreVblankStartEvent(queue, handle) == 0, "pre-vblank unsubscription failed");
     std::vector<std::byte> allocation(65536 + 65535);
     const auto storage = alignedBuffer(allocation);
     VideoOutBuffers buffer{storage.data(), nullptr, {allocation.data(), storage.data()}};

docs/dev/TechnicalDebt.md

@@ -239,6 +239,7 @@ Throughout the project, every function at every stage either **does exactly what
 - [sceAjmBatchJobSetResampleParameters, sceAjmBatchJobGetResampleInfo](../../core/libs/prx/libSceAjm.native/src/Ajm.cpp) (libSceAjm) - the ratio is taken as decoded samples per output sample and num_samples as the decoded samples the resampler holds, both inferred from FMOD (Hades II); the console's interpolation is unknown, a 4-point Catmull-Rom is used. The flags argument is ignored, as in shadPS4 and Kyty
 - [scePlayerReviewDialogOpen, scePlayerReviewDialogGetResult](../../core/libs/prx/libSceCdlgPlayerReview/Export.cpp) (libSceCdlgPlayerReview) - the PS5-only dialog has no public reference: the parameter is not read and the result is assumed to start with the 32-bit common dialog result, as `sceWebBrowserDialogGetResult` assumes
 - [sceHttpWaitRequest](../../core/libs/prx/libSceHttp/Export.cpp) (libSceHttp) - the timeout is assumed to be in microseconds and a negative timeout to wait without limit; the invalid-value error for a null handle or event array or a non-positive event count is assumed, not measured. No request is ever pending, so the call waits for the timeout and returns 0 events, and a wait without limit throws
+- [sceVideoOutAddPreVblankStartEvent](../../core/libs/prx/libSceVideoOut/src/Event.cpp) (libSceVideoOut) - how long before the vblank the console signals pre-vblank start is unknown. The event is triggered on each emulated vblank tick immediately before the vblank event, with its own count as the event data
 
 ### Functional