From c720211542c2741b1b768a25a4a00ad3511be856 Mon Sep 17 00:00:00 2001
From: Martino Fontana <tinozzo123@gmail.com>
Date: Sun, 27 Apr 2025 13:08:33 +0200
Subject: [PATCH] VideoCommon: Limit maximum denominator for MPEG4 It happened
 to be under the limit normally, but now that the VBI rate can be changed,
 that's no longer the case.

---
 Source/Core/VideoCommon/FrameDumpFFMpeg.cpp | 13 +++++++++----
 Source/Core/VideoCommon/FrameDumpFFMpeg.h   |  4 ++++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Source/Core/VideoCommon/FrameDumpFFMpeg.cpp b/Source/Core/VideoCommon/FrameDumpFFMpeg.cpp
index ea8bda7893..44ec0a6a27 100644
--- a/Source/Core/VideoCommon/FrameDumpFFMpeg.cpp
+++ b/Source/Core/VideoCommon/FrameDumpFFMpeg.cpp
@@ -62,13 +62,13 @@ struct FrameDumpContext
 
 namespace
 {
-AVRational GetTimeBaseForCurrentRefreshRate()
+AVRational GetTimeBaseForCurrentRefreshRate(s64 max_denominator)
 {
   auto& vi = Core::System::GetInstance().GetVideoInterface();
   int num;
   int den;
   av_reduce(&num, &den, int(vi.GetTargetRefreshRateDenominator()),
-            int(vi.GetTargetRefreshRateNumerator()), std::numeric_limits<int>::max());
+            int(vi.GetTargetRefreshRateNumerator()), max_denominator);
   return AVRational{num, den};
 }
 
@@ -248,11 +248,16 @@ bool FFMpegFrameDump::CreateVideoFile()
     return false;
   }
 
+  m_max_denominator = std::numeric_limits<s64>::max();
+
   // Force XVID FourCC for better compatibility when using H.263
   if (codec->id == AV_CODEC_ID_MPEG4)
+  {
     m_context->codec->codec_tag = MKTAG('X', 'V', 'I', 'D');
+    m_max_denominator = std::numeric_limits<unsigned short>::max();
+  }
 
-  const auto time_base = GetTimeBaseForCurrentRefreshRate();
+  const auto time_base = GetTimeBaseForCurrentRefreshRate(m_max_denominator);
 
   INFO_LOG_FMT(FRAMEDUMP, "Creating video file: {} x {} @ {}/{} fps", m_context->width,
                m_context->height, time_base.den, time_base.num);
@@ -535,7 +540,7 @@ FrameState FFMpegFrameDump::FetchState(u64 ticks, int frame_number) const
   state.frame_number = frame_number;
   state.savestate_index = m_savestate_index;
 
-  const auto time_base = GetTimeBaseForCurrentRefreshRate();
+  const auto time_base = GetTimeBaseForCurrentRefreshRate(m_max_denominator);
   state.refresh_rate_num = time_base.den;
   state.refresh_rate_den = time_base.num;
   return state;
diff --git a/Source/Core/VideoCommon/FrameDumpFFMpeg.h b/Source/Core/VideoCommon/FrameDumpFFMpeg.h
index 8431e24274..87387b3e41 100644
--- a/Source/Core/VideoCommon/FrameDumpFFMpeg.h
+++ b/Source/Core/VideoCommon/FrameDumpFFMpeg.h
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <ctime>
+#include <limits>
 #include <memory>
 
 #include "Common/CommonTypes.h"
@@ -62,6 +63,9 @@ private:
   // Used for filename generation.
   std::time_t m_start_time = {};
   u32 m_file_index = 0;
+
+  // Some codecs (like MPEG4) have a limit to this
+  int64_t m_max_denominator = std::numeric_limits<s64>::max();
 };
 
 #if !defined(HAVE_FFMPEG)