Merge pull request #1227 from ggrtk/auto-aspect-ratio

GPU: Add auto aspect ratio and various fixes

src/core/gpu.cpp

@@ -7,6 +7,7 @@
 #include "host_display.h"
 #include "host_interface.h"
 #include "interrupt_controller.h"
+#include "settings.h"
 #include "stb_image_write.h"
 #include "system.h"
 #include "timers.h"
@@ -161,13 +162,13 @@ bool GPU::DoState(StateWrapper& sw, bool update_display)
   sw.Do(&m_crtc_state.display_vram_width);
   sw.Do(&m_crtc_state.display_vram_height);
   sw.Do(&m_crtc_state.horizontal_total);
-  sw.Do(&m_crtc_state.horizontal_active_start);
+  sw.Do(&m_crtc_state.horizontal_visible_start);
-  sw.Do(&m_crtc_state.horizontal_active_end);
+  sw.Do(&m_crtc_state.horizontal_visible_end);
   sw.Do(&m_crtc_state.horizontal_display_start);
   sw.Do(&m_crtc_state.horizontal_display_end);
   sw.Do(&m_crtc_state.vertical_total);
-  sw.Do(&m_crtc_state.vertical_active_start);
+  sw.Do(&m_crtc_state.vertical_visible_start);
-  sw.Do(&m_crtc_state.vertical_active_end);
+  sw.Do(&m_crtc_state.vertical_visible_end);
   sw.Do(&m_crtc_state.vertical_display_start);
   sw.Do(&m_crtc_state.vertical_display_end);
   sw.Do(&m_crtc_state.fractional_ticks);
@@ -448,9 +449,41 @@ float GPU::ComputeVerticalFrequency() const
 float GPU::GetDisplayAspectRatio() const
 {
   if (g_settings.display_force_4_3_for_24bit && m_GPUSTAT.display_area_color_depth_24)
+  {
     return 4.0f / 3.0f;
+  }
+  else if (g_settings.display_aspect_ratio == DisplayAspectRatio::Auto)
+  {
+    const CRTCState& cs = m_crtc_state;
+    float relative_width = static_cast<float>(cs.horizontal_visible_end - cs.horizontal_visible_start);
+    float relative_height = static_cast<float>(cs.vertical_visible_end - cs.vertical_visible_start);
+
+    if (relative_width <= 0 || relative_height <= 0)
+      return 4.0f / 3.0f;
+
+    if (m_GPUSTAT.pal_mode)
+    {
+      relative_width /= static_cast<float>(PAL_HORIZONTAL_ACTIVE_END - PAL_HORIZONTAL_ACTIVE_START);
+      relative_height /= static_cast<float>(PAL_VERTICAL_ACTIVE_END - PAL_VERTICAL_ACTIVE_START);
+    }
+    else
+    {
+      relative_width /= static_cast<float>(NTSC_HORIZONTAL_ACTIVE_END - NTSC_HORIZONTAL_ACTIVE_START);
+      relative_height /= static_cast<float>(NTSC_VERTICAL_ACTIVE_END - NTSC_VERTICAL_ACTIVE_START);
+    }
+    return (relative_width / relative_height) * (4.0f / 3.0f);
+  }
+  else if (g_settings.display_aspect_ratio == DisplayAspectRatio::PAR1_1)
+  {
+    if (m_crtc_state.display_width == 0 || m_crtc_state.display_height == 0)
+      return 4.0f / 3.0f;
+
+    return static_cast<float>(m_crtc_state.display_width) / static_cast<float>(m_crtc_state.display_height);
+  }
   else
+  {
     return Settings::GetDisplayAspectRatioValue(g_settings.display_aspect_ratio);
+  }
 }
 
 void GPU::UpdateCRTCConfig()
@@ -537,54 +570,74 @@ void GPU::UpdateCRTCDisplayParameters()
     switch (crop_mode)
     {
       case DisplayCropMode::None:
-        cs.horizontal_active_start = static_cast<u16>(std::max<int>(0, 487 + g_settings.display_active_start_offset));
+        cs.horizontal_visible_start = PAL_HORIZONTAL_ACTIVE_START;
-        cs.horizontal_active_end = static_cast<u16>(std::max<int>(0, 3282 + g_settings.display_active_end_offset));
+        cs.horizontal_visible_end = PAL_HORIZONTAL_ACTIVE_END;
-        cs.vertical_active_start = static_cast<u16>(std::max<int>(0, 20 + g_settings.display_line_start_offset));
+        cs.vertical_visible_start = PAL_VERTICAL_ACTIVE_START;
-        cs.vertical_active_end = static_cast<u16>(std::max<int>(0, 308 + g_settings.display_line_end_offset));
+        cs.vertical_visible_end = PAL_VERTICAL_ACTIVE_END;
         break;
 
       case DisplayCropMode::Overscan:
-        cs.horizontal_active_start = static_cast<u16>(std::max<int>(0, 628 + g_settings.display_active_start_offset));
+        cs.horizontal_visible_start = static_cast<u16>(std::max<int>(0, 628 + g_settings.display_active_start_offset));
-        cs.horizontal_active_end = static_cast<u16>(std::max<int>(0, 3188 + g_settings.display_active_end_offset));
+        cs.horizontal_visible_end =
-        cs.vertical_active_start = static_cast<u16>(std::max<int>(0, 30 + g_settings.display_line_start_offset));
+          static_cast<u16>(std::max<int>(cs.horizontal_visible_start, 3188 + g_settings.display_active_end_offset));
-        cs.vertical_active_end = static_cast<u16>(std::max<int>(0, 298 + g_settings.display_line_end_offset));
+        cs.vertical_visible_start = static_cast<u16>(std::max<int>(0, 30 + g_settings.display_line_start_offset));
+        cs.vertical_visible_end =
+          static_cast<u16>(std::max<int>(cs.vertical_visible_start, 298 + g_settings.display_line_end_offset));
         break;
 
       case DisplayCropMode::Borders:
       default:
-        cs.horizontal_active_start = horizontal_display_start;
+        cs.horizontal_visible_start = horizontal_display_start;
-        cs.horizontal_active_end = horizontal_display_end;
+        cs.horizontal_visible_end = horizontal_display_end;
-        cs.vertical_active_start = vertical_display_start;
+        cs.vertical_visible_start = vertical_display_start;
-        cs.vertical_active_end = vertical_display_end;
+        cs.vertical_visible_end = vertical_display_end;
         break;
     }
+    cs.horizontal_visible_start =
+      std::clamp<u16>(cs.horizontal_visible_start, PAL_HORIZONTAL_ACTIVE_START, PAL_HORIZONTAL_ACTIVE_END);
+    cs.horizontal_visible_end =
+      std::clamp<u16>(cs.horizontal_visible_end, cs.horizontal_visible_start, PAL_HORIZONTAL_ACTIVE_END);
+    cs.vertical_visible_start =
+      std::clamp<u16>(cs.vertical_visible_start, PAL_VERTICAL_ACTIVE_START, PAL_VERTICAL_ACTIVE_END);
+    cs.vertical_visible_end =
+      std::clamp<u16>(cs.vertical_visible_end, cs.vertical_visible_start, PAL_VERTICAL_ACTIVE_END);
   }
   else
   {
     switch (crop_mode)
     {
       case DisplayCropMode::None:
-        cs.horizontal_active_start = static_cast<u16>(std::max<int>(0, 488 + g_settings.display_active_start_offset));
+        cs.horizontal_visible_start = NTSC_HORIZONTAL_ACTIVE_START;
-        cs.horizontal_active_end = static_cast<u16>(std::max<int>(0, 3288 + g_settings.display_active_end_offset));
+        cs.horizontal_visible_end = NTSC_HORIZONTAL_ACTIVE_END;
-        cs.vertical_active_start = static_cast<u16>(std::max<int>(0, 16 + g_settings.display_line_start_offset));
+        cs.vertical_visible_start = NTSC_VERTICAL_ACTIVE_START;
-        cs.vertical_active_end = static_cast<u16>(std::max<int>(0, 256 + g_settings.display_line_end_offset));
+        cs.vertical_visible_end = NTSC_VERTICAL_ACTIVE_END;
         break;
 
       case DisplayCropMode::Overscan:
-        cs.horizontal_active_start = static_cast<u16>(std::max<int>(0, 608 + g_settings.display_active_start_offset));
+        cs.horizontal_visible_start = static_cast<u16>(std::max<int>(0, 608 + g_settings.display_active_start_offset));
-        cs.horizontal_active_end = static_cast<u16>(std::max<int>(0, 3168 + g_settings.display_active_end_offset));
+        cs.horizontal_visible_end =
-        cs.vertical_active_start = static_cast<u16>(std::max<int>(0, 24 + g_settings.display_line_start_offset));
+          static_cast<u16>(std::max<int>(cs.horizontal_visible_start, 3168 + g_settings.display_active_end_offset));
-        cs.vertical_active_end = static_cast<u16>(std::max<int>(0, 248 + g_settings.display_line_end_offset));
+        cs.vertical_visible_start = static_cast<u16>(std::max<int>(0, 24 + g_settings.display_line_start_offset));
+        cs.vertical_visible_end =
+          static_cast<u16>(std::max<int>(cs.vertical_visible_start, 248 + g_settings.display_line_end_offset));
         break;
 
       case DisplayCropMode::Borders:
       default:
-        cs.horizontal_active_start = horizontal_display_start;
+        cs.horizontal_visible_start = horizontal_display_start;
-        cs.horizontal_active_end = horizontal_display_end;
+        cs.horizontal_visible_end = horizontal_display_end;
-        cs.vertical_active_start = vertical_display_start;
+        cs.vertical_visible_start = vertical_display_start;
-        cs.vertical_active_end = vertical_display_end;
+        cs.vertical_visible_end = vertical_display_end;
         break;
     }
+    cs.horizontal_visible_start =
+      std::clamp<u16>(cs.horizontal_visible_start, NTSC_HORIZONTAL_ACTIVE_START, NTSC_HORIZONTAL_ACTIVE_END);
+    cs.horizontal_visible_end =
+      std::clamp<u16>(cs.horizontal_visible_end, cs.horizontal_visible_start, NTSC_HORIZONTAL_ACTIVE_END);
+    cs.vertical_visible_start =
+      std::clamp<u16>(cs.vertical_visible_start, NTSC_VERTICAL_ACTIVE_START, NTSC_VERTICAL_ACTIVE_END);
+    cs.vertical_visible_end =
+      std::clamp<u16>(cs.vertical_visible_end, cs.vertical_visible_start, NTSC_VERTICAL_ACTIVE_END);
   }
 
   // If force-progressive is enabled, we only double the height in 480i mode. This way non-interleaved 480i framebuffers
@@ -593,8 +646,8 @@ void GPU::UpdateCRTCDisplayParameters()
   const u8 height_shift = m_force_progressive_scan ? y_shift : BoolToUInt8(m_GPUSTAT.vertical_interlace);
 
   // Determine screen size.
-  cs.display_width = (cs.horizontal_active_end - cs.horizontal_active_start) / cs.dot_clock_divider;
+  cs.display_width = (cs.horizontal_visible_end - cs.horizontal_visible_start) / cs.dot_clock_divider;
-  cs.display_height = (cs.vertical_active_end - cs.vertical_active_start) << height_shift;
+  cs.display_height = (cs.vertical_visible_end - cs.vertical_visible_start) << height_shift;
 
   // Determine number of pixels outputted from VRAM (in general, round to 4-pixel multiple).
   // TODO: Verify behavior if values are outside of the active video portion of scanline.
@@ -610,17 +663,17 @@ void GPU::UpdateCRTCDisplayParameters()
   // Determine if we need to adjust the VRAM rectangle (because the display is starting outside the visible area) or add
   // padding.
   u16 horizontal_skip_pixels;
-  if (horizontal_display_start >= cs.horizontal_active_start)
+  if (horizontal_display_start >= cs.horizontal_visible_start)
   {
-    cs.display_origin_left = (horizontal_display_start - cs.horizontal_active_start) / cs.dot_clock_divider;
+    cs.display_origin_left = (horizontal_display_start - cs.horizontal_visible_start) / cs.dot_clock_divider;
-    cs.display_vram_left = std::min<u16>(m_crtc_state.regs.X, VRAM_WIDTH - 1);
+    cs.display_vram_left = cs.regs.X;
     horizontal_skip_pixels = 0;
   }
   else
   {
-    horizontal_skip_pixels = (cs.horizontal_active_start - horizontal_display_start) / cs.dot_clock_divider;
+    horizontal_skip_pixels = (cs.horizontal_visible_start - horizontal_display_start) / cs.dot_clock_divider;
     cs.display_origin_left = 0;
-    cs.display_vram_left = std::min<u16>(m_crtc_state.regs.X + horizontal_skip_pixels, VRAM_WIDTH - 1);
+    cs.display_vram_left = (cs.regs.X + horizontal_skip_pixels) % VRAM_WIDTH;
   }
 
   // apply the crop from the start (usually overscan)
@@ -629,28 +682,29 @@ void GPU::UpdateCRTCDisplayParameters()
   // Apply crop from the end by shrinking VRAM rectangle width if display would end outside the visible area.
   cs.display_vram_width = std::min<u16>(cs.display_vram_width, cs.display_width - cs.display_origin_left);
 
-  if (vertical_display_start >= cs.vertical_active_start)
+  if (vertical_display_start >= cs.vertical_visible_start)
   {
-    cs.display_origin_top = (vertical_display_start - cs.vertical_active_start) << y_shift;
+    cs.display_origin_top = (vertical_display_start - cs.vertical_visible_start) << y_shift;
-    cs.display_vram_top = m_crtc_state.regs.Y;
+    cs.display_vram_top = cs.regs.Y;
   }
   else
   {
     cs.display_origin_top = 0;
-    cs.display_vram_top = m_crtc_state.regs.Y + ((cs.vertical_active_start - vertical_display_start) << y_shift);
+    cs.display_vram_top = (cs.regs.Y + ((cs.vertical_visible_start - vertical_display_start) << y_shift)) % VRAM_HEIGHT;
   }
 
-  if (vertical_display_end <= cs.vertical_active_end)
+  if (vertical_display_end <= cs.vertical_visible_end)
   {
-    cs.display_vram_height = (vertical_display_end - std::min(vertical_display_end, std::max(vertical_display_start,
+    cs.display_vram_height =
-                                                                                             cs.vertical_active_start)))
+      (vertical_display_end -
-                             << height_shift;
+       std::min(vertical_display_end, std::max(vertical_display_start, cs.vertical_visible_start)))
+      << height_shift;
   }
   else
   {
     cs.display_vram_height =
-      (cs.vertical_active_end -
+      (cs.vertical_visible_end -
-       std::min(cs.vertical_active_end, std::max(vertical_display_start, cs.vertical_active_start)))
+       std::min(cs.vertical_visible_end, std::max(vertical_display_start, cs.vertical_visible_start)))
       << height_shift;
   }
 }
@@ -887,8 +941,8 @@ bool GPU::ConvertScreenCoordinatesToBeamTicksAndLines(s32 window_x, s32 window_y
   }
 
   *out_line =
-    (static_cast<u32>(display_y) >> BoolToUInt8(m_GPUSTAT.vertical_interlace)) + m_crtc_state.vertical_active_start;
+    (static_cast<u32>(display_y) >> BoolToUInt8(m_GPUSTAT.vertical_interlace)) + m_crtc_state.vertical_visible_start;
-  *out_tick = (static_cast<u32>(display_x) * m_crtc_state.dot_clock_divider) + m_crtc_state.horizontal_active_start;
+  *out_tick = (static_cast<u32>(display_x) * m_crtc_state.dot_clock_divider) + m_crtc_state.horizontal_visible_start;
   return true;
 }
 
@@ -1532,9 +1586,9 @@ void GPU::DrawDebugStateWindow()
                 cs.horizontal_display_start / cs.dot_clock_divider, cs.horizontal_display_end / cs.dot_clock_divider,
                 cs.vertical_display_start, cs.vertical_display_end);
     ImGui::Text("Cropping: %s", Settings::GetDisplayCropModeName(g_settings.display_crop_mode));
-    ImGui::Text("Visible Display Range: %u-%u (%u-%u), %u-%u", cs.horizontal_active_start, cs.horizontal_active_end,
+    ImGui::Text("Visible Display Range: %u-%u (%u-%u), %u-%u", cs.horizontal_visible_start, cs.horizontal_visible_end,
-                cs.horizontal_active_start / cs.dot_clock_divider, cs.horizontal_active_end / cs.dot_clock_divider,
+                cs.horizontal_visible_start / cs.dot_clock_divider, cs.horizontal_visible_end / cs.dot_clock_divider,
-                cs.vertical_active_start, cs.vertical_active_end);
+                cs.vertical_visible_start, cs.vertical_visible_end);
     ImGui::Text("Display Resolution: %ux%u", cs.display_width, cs.display_height);
     ImGui::Text("Display Origin: %u, %u", cs.display_origin_left, cs.display_origin_top);
     ImGui::Text("Displayed/Visible VRAM Portion: %ux%u @ (%u, %u)", cs.display_vram_width, cs.display_vram_height,

src/core/gpu.h

@@ -56,6 +56,18 @@ public:
     PAL_TOTAL_LINES = 314,
   };
 
+  enum : u16
+  {
+    NTSC_HORIZONTAL_ACTIVE_START = 488,
+    NTSC_HORIZONTAL_ACTIVE_END = 3288,
+    NTSC_VERTICAL_ACTIVE_START = 16,
+    NTSC_VERTICAL_ACTIVE_END = 256,
+    PAL_HORIZONTAL_ACTIVE_START = 487,
+    PAL_HORIZONTAL_ACTIVE_END = 3282,
+    PAL_VERTICAL_ACTIVE_START = 20,
+    PAL_VERTICAL_ACTIVE_END = 308,
+  };
+
   // Base class constructor.
   GPU();
   virtual ~GPU();
@@ -89,7 +101,7 @@ public:
   }
   void EndDMAWrite();
 
-  /// Returns false if the DAC is loading any data from VRAM.
+  /// Returns true if no data is being sent from VRAM to the DAC or that no portion of VRAM would be visible on screen.
   ALWAYS_INLINE bool IsDisplayDisabled() const
   {
     return m_GPUSTAT.display_disable || m_crtc_state.display_vram_width == 0 || m_crtc_state.display_vram_height == 0;
@@ -98,13 +110,13 @@ public:
   /// Returns true if scanout should be interlaced.
   ALWAYS_INLINE bool IsInterlacedDisplayEnabled() const
   {
-    return (!m_force_progressive_scan) & m_GPUSTAT.vertical_interlace;
+    return (!m_force_progressive_scan) && m_GPUSTAT.vertical_interlace;
   }
 
   /// Returns true if interlaced rendering is enabled and force progressive scan is disabled.
   ALWAYS_INLINE bool IsInterlacedRenderingEnabled() const
   {
-    return (!m_force_progressive_scan) & m_GPUSTAT.SkipDrawingToActiveField();
+    return (!m_force_progressive_scan) && m_GPUSTAT.SkipDrawingToActiveField();
   }
 
   /// Returns the number of pending GPU ticks.
@@ -475,28 +487,31 @@ protected:
     u16 display_width;
     u16 display_height;
 
-    // Top-left corner where the VRAM is displayed. Depending on the CRTC config, this may indicate padding.
+    // Top-left corner in screen coordinates where the outputted portion of VRAM is first visible.
     u16 display_origin_left;
     u16 display_origin_top;
 
-    // Rectangle describing the displayed area of VRAM, in coordinates.
+    // Rectangle in VRAM coordinates describing the area of VRAM that is visible on screen.
     u16 display_vram_left;
     u16 display_vram_top;
     u16 display_vram_width;
     u16 display_vram_height;
 
-    u16 horizontal_total;
+    // Visible range of the screen, in GPU ticks/lines. Clamped to lie within the active video region.
-    u16 horizontal_sync_start; // <- not currently saved to state, so we don't have to bump the version
+    u16 horizontal_visible_start;
-    u16 horizontal_active_start;
+    u16 horizontal_visible_end;
-    u16 horizontal_active_end;
+    u16 vertical_visible_start;
+    u16 vertical_visible_end;
+
     u16 horizontal_display_start;
     u16 horizontal_display_end;
-    u16 vertical_total;
-    u16 vertical_active_start;
-    u16 vertical_active_end;
     u16 vertical_display_start;
     u16 vertical_display_end;
 
+    u16 horizontal_total;
+    u16 horizontal_sync_start; // <- not currently saved to state, so we don't have to bump the version
+    u16 vertical_total;
+
     TickCount fractional_ticks;
     TickCount current_tick_in_scanline;
     u32 current_scanline;

src/core/gte.cpp

@@ -655,6 +655,7 @@ static void RTPS(const s16 V[3], u8 shift, bool lm, bool last)
         Sx = ((((s64(result) * s64(REGS.IR1)) * s64(7)) / s64(6)) + s64(REGS.OFX));
         break;
 
+      case DisplayAspectRatio::Auto:
       case DisplayAspectRatio::R4_3:
       case DisplayAspectRatio::PAR1_1:
       default:
@@ -747,6 +748,7 @@ static void RTPS(const s16 V[3], u8 shift, bool lm, bool last)
           precise_x = (precise_x * 7.0f) / 6.0f;
           break;
 
+        case DisplayAspectRatio::Auto:
         case DisplayAspectRatio::R4_3:
         case DisplayAspectRatio::PAR1_1:
         default:

src/core/host_display.cpp

@@ -138,7 +138,6 @@ void HostDisplay::CalculateDrawRect(s32 window_width, s32 window_height, s32* ou
                                     s32* out_height, s32* out_left_padding, s32* out_top_padding, float* out_scale,
                                     float* out_y_scale, bool apply_aspect_ratio) const
 {
-  apply_aspect_ratio = (m_display_aspect_ratio > 0) ? apply_aspect_ratio : false;
   const float y_scale =
     apply_aspect_ratio ?
       ((static_cast<float>(m_display_width) / static_cast<float>(m_display_height)) / m_display_aspect_ratio) :

src/core/settings.cpp

@@ -625,10 +625,11 @@ const char* Settings::GetDisplayCropModeDisplayName(DisplayCropMode crop_mode)
   return s_display_crop_mode_display_names[static_cast<int>(crop_mode)];
 }
 
-static std::array<const char*, 11> s_display_aspect_ratio_names = {
+static std::array<const char*, 12> s_display_aspect_ratio_names = {{"Auto (Game Native)", "4:3", "16:9", "16:10",
-  {"4:3", "16:9", "16:10", "19:9", "21:9", "8:7", "5:4", "3:2", "2:1 (VRAM 1:1)", "1:1", "PAR 1:1"}};
+                                                                    "19:9", "21:9", "8:7", "5:4", "3:2",
-static constexpr std::array<float, 11> s_display_aspect_ratio_values = {
+                                                                    "2:1 (VRAM 1:1)", "1:1", "PAR 1:1"}};
-  {4.0f / 3.0f, 16.0f / 9.0f, 16.0f / 10.0f, 19.0f / 9.0f, 21.0f / 9.0f, 8.0f / 7.0f, 5.0f / 4.0f, 3.0f / 2.0f,
+static constexpr std::array<float, 12> s_display_aspect_ratio_values = {
+  {-1.0f, 4.0f / 3.0f, 16.0f / 9.0f, 16.0f / 10.0f, 19.0f / 9.0f, 21.0f / 9.0f, 8.0f / 7.0f, 5.0f / 4.0f, 3.0f / 2.0f,
    2.0f / 1.0f, 1.0f, -1.0f}};
 
 std::optional<DisplayAspectRatio> Settings::ParseDisplayAspectRatio(const char* str)

src/core/settings.h

@@ -111,15 +111,11 @@ struct Settings
   bool gpu_pgxp_cpu = false;
   bool gpu_pgxp_preserve_proj_fp = false;
   DisplayCropMode display_crop_mode = DisplayCropMode::None;
-  DisplayAspectRatio display_aspect_ratio = DisplayAspectRatio::R4_3;
+  DisplayAspectRatio display_aspect_ratio = DisplayAspectRatio::Auto;
   s16 display_active_start_offset = 0;
   s16 display_active_end_offset = 0;
   s8 display_line_start_offset = 0;
   s8 display_line_end_offset = 0;
-  s8 display_crop_left = 0;
-  s8 display_crop_right = 0;
-  s8 display_crop_top = 0;
-  s8 display_crop_bottom = 0;
   bool display_force_4_3_for_24bit = false;
   bool gpu_24bit_chroma_smoothing = false;
   bool display_linear_filtering = true;
@@ -304,7 +300,7 @@ struct Settings
 #endif
 
   static constexpr DisplayCropMode DEFAULT_DISPLAY_CROP_MODE = DisplayCropMode::Overscan;
-  static constexpr DisplayAspectRatio DEFAULT_DISPLAY_ASPECT_RATIO = DisplayAspectRatio::R4_3;
+  static constexpr DisplayAspectRatio DEFAULT_DISPLAY_ASPECT_RATIO = DisplayAspectRatio::Auto;
   static constexpr ControllerType DEFAULT_CONTROLLER_1_TYPE = ControllerType::DigitalController;
   static constexpr ControllerType DEFAULT_CONTROLLER_2_TYPE = ControllerType::None;
   static constexpr MemoryCardType DEFAULT_MEMORY_CARD_1_TYPE = MemoryCardType::PerGameTitle;

src/core/types.h

@@ -85,6 +85,7 @@ enum class DisplayCropMode : u8
 
 enum class DisplayAspectRatio : u8
 {
+  Auto,
   R4_3,
   R16_9,
   R16_10,

src/duckstation-libretro/libretro_host_interface.cpp

@@ -704,7 +704,8 @@ static std::array<retro_core_option_definition, 49> s_option_definitions = {{
   {"duckstation_Display.AspectRatio",
    "Aspect Ratio",
    "Sets the core-provided aspect ratio.",
-   {{"4:3", "4:3"},
+   {{"Auto", "Auto (Game Native)"},
+    {"4:3", "4:3"},
     {"16:9", "16:9"},
     {"16:10", "16:10"},
     {"19:9", "19:9"},
@@ -715,7 +716,7 @@ static std::array<retro_core_option_definition, 49> s_option_definitions = {{
     {"2:1 (VRAM 1:1)", "2:1 (VRAM 1:1)"},
     {"1:1", "1:1"},
     {"PAR 1:1", "PAR 1:1"}},
-   "4:3"},
+   "Auto"},
   {"duckstation_Main.LoadDevicesFromSaveStates",
    "Load Devices From Save States",
    "Sets whether the contents of devices and memory cards will be loaded when a save state is loaded.",

src/duckstation-qt/displaysettingswidget.cpp

@@ -62,9 +62,9 @@ DisplaySettingsWidget::DisplaySettingsWidget(QtHostInterface* host_interface, QW
        "renderers. <br>This option is only supported in Direct3D and Vulkan. OpenGL will always use the default "
        "device."));
   dialog->registerWidgetHelp(
-    m_ui.displayAspectRatio, tr("Aspect Ratio"), QStringLiteral("4:3"),
+    m_ui.displayAspectRatio, tr("Aspect Ratio"), QStringLiteral("Auto (Game Native)"),
-    tr("Changes the aspect ratio used to display the console's output to the screen. The default "
+    tr("Changes the aspect ratio used to display the console's output to the screen. The default is Auto (Game Native) "
-       "is 4:3 which matches a typical TV of the era."));
+       "which automatically adjusts the aspect ratio to match how a game would be shown on a typical TV of the era."));
   dialog->registerWidgetHelp(
     m_ui.displayCropMode, tr("Crop Mode"), tr("Only Overscan Area"),
     tr("Determines how much of the area typically not visible on a consumer TV set to crop/hide. <br>"