From c49f0e5c6e574601f05538c9f3eef1ae7f8f2ddc Mon Sep 17 00:00:00 2001
From: Irastris <irastris15@gmail.com>
Date: Sat, 23 May 2026 09:18:29 -0400
Subject: [PATCH] Use std::chrono for THP playback pacing (#1757)

* Use std::chrono for THP playback pacing

* Redundant include
---
 include/d/actor/d_a_movie_player.h |  2 ++
 src/d/actor/d_a_movie_player.cpp   | 30 +++++++++++++++++++++---------
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/include/d/actor/d_a_movie_player.h b/include/d/actor/d_a_movie_player.h
index 0e666ae470..c382e0d1f7 100644
--- a/include/d/actor/d_a_movie_player.h
+++ b/include/d/actor/d_a_movie_player.h
@@ -5,6 +5,7 @@
 #include <thp.h>
 #else
 #include <atomic>
+#include <chrono>
 #endif
 #include "f_op/f_op_actor.h"
 #include "d/d_drawlist.h"
@@ -125,6 +126,7 @@ struct daMP_THPPlayer {
 	/* 0x0D4 */ s32 curCount;
 #if TARGET_PC
 	/* 0x0D8 */ std::atomic<s32> videoDecodeCount;
+	std::chrono::steady_clock::time_point thpPlaybackClock;
 #else
 	/* 0x0D8 */ s32 videoDecodeCount;
 #endif
diff --git a/src/d/actor/d_a_movie_player.cpp b/src/d/actor/d_a_movie_player.cpp
index 1f8bdeecd7..fcd1fb6dff 100644
--- a/src/d/actor/d_a_movie_player.cpp
+++ b/src/d/actor/d_a_movie_player.cpp
@@ -26,15 +26,16 @@
 
 #include "f_op/f_op_overlap_mng.h"
 
+#include "JSystem/JAudio2/JASCriticalSection.h"
+
+#if TARGET_PC
 #include "dusk/gx_helper.h"
 #include "dusk/os.h"
 #include "dusk/layout.hpp"
-
-#include "JSystem/JAudio2/JASCriticalSection.h"
-
 #if MOVIE_SUPPORT
 #include "turbojpeg.h"
 #endif
+#endif
 
 inline s32 daMP_NEXT_READ_SIZE(daMP_THPReadBuffer* readBuf) {
     return *(BE(s32)*)readBuf->ptr;
@@ -3912,13 +3913,20 @@ static BOOL daMP_ProperTimingForGettingNextFrame() {
 			return TRUE;
 		}
 	} else {
-		s32 frameRate = daMP_ActivePlayer.header.frameRate * 100.0f;
 #if TARGET_PC
-	    // DUSK HACK: We only fire retrace callbacks *half* as often as the game expects,
-	    // because we only run them once per frame, and normally there should be two scans
-	    // per game frame.
-	    frameRate *= 2;
-#endif
+		const f32 fps = daMP_ActivePlayer.header.frameRate;
+		if (fps > 0.0f) {
+			const f32 elapsed = std::chrono::duration<f32>(
+			    std::chrono::steady_clock::now() - daMP_ActivePlayer.thpPlaybackClock).count();
+			const s32 desired = static_cast<s32>(elapsed * fps);
+			if (desired != daMP_ActivePlayer.prevCount) {
+				daMP_ActivePlayer.prevCount = desired;
+				daMP_ActivePlayer.curCount = desired;
+				return TRUE;
+			}
+		}
+#else
+		s32 frameRate = daMP_ActivePlayer.header.frameRate * 100.0f;
 		if (VIGetTvFormat() == VI_PAL) {
 			daMP_ActivePlayer.curCount = daMP_ActivePlayer.retaceCount * frameRate / 5000;
 		} else {
@@ -3929,6 +3937,7 @@ static BOOL daMP_ProperTimingForGettingNextFrame() {
 			daMP_ActivePlayer.prevCount = daMP_ActivePlayer.curCount;
 			return TRUE;
 		}
+#endif
 	}
 
 	return FALSE;
@@ -4133,6 +4142,9 @@ static BOOL daMP_THPPlayerPlay() {
         daMP_ActivePlayer.prevCount = 0;
         daMP_ActivePlayer.curCount = 0;
         daMP_ActivePlayer.retaceCount = -1;
+#if TARGET_PC
+        daMP_ActivePlayer.thpPlaybackClock = std::chrono::steady_clock::now();
+#endif
         return TRUE;
     }