Add black_frame_insertion support for 120 Hz monitors.

config.def.h

@@ -215,6 +215,10 @@ static const bool hard_sync = false;
 // 2: Etc ...
 static const unsigned hard_sync_frames = 0;
 
+// Inserts a black frame inbetween frames.
+// Useful for 120 Hz monitors who want to play 60 Hz material with eliminated ghosting. video_refresh_rate should still be configured as if it is a 60 Hz monitor (divide refresh rate by 2).
+static bool black_frame_insertion = false;
+
 // Threaded video. Will possibly increase performance significantly at cost of worse synchronization and latency.
 static const bool video_threaded = false;
 

frontend/menu/menu_common.h

@@ -118,6 +118,7 @@ typedef enum
    RGUI_SETTINGS_VIDEO_VSYNC,
    RGUI_SETTINGS_VIDEO_HARD_SYNC,
    RGUI_SETTINGS_VIDEO_HARD_SYNC_FRAMES,
+   RGUI_SETTINGS_VIDEO_BLACK_FRAME_INSERTION,
    RGUI_SETTINGS_VIDEO_REFRESH_RATE_AUTO,
    RGUI_SETTINGS_VIDEO_OPTIONS_LAST,
 #ifdef HAVE_SHADER_MANAGER

frontend/menu/rgui.c

@@ -598,6 +598,9 @@ static void render_text(rgui_handle_t *rgui)
             case RGUI_SETTINGS_VIDEO_HARD_SYNC:
                strlcpy(type_str, g_settings.video.hard_sync ? "ON" : "OFF", sizeof(type_str));
                break;
+            case RGUI_SETTINGS_VIDEO_BLACK_FRAME_INSERTION:
+               strlcpy(type_str, g_settings.video.black_frame_insertion ? "ON" : "OFF", sizeof(type_str));
+               break;
             case RGUI_SETTINGS_VIDEO_HARD_SYNC_FRAMES:
                snprintf(type_str, sizeof(type_str), "%u", g_settings.video.hard_sync_frames);
                break;
@@ -1505,6 +1508,7 @@ static void rgui_settings_video_options_populate_entries(rgui_handle_t *rgui)
    rgui_list_push(rgui->selection_buf, "VSync", RGUI_SETTINGS_VIDEO_VSYNC, 0);
    rgui_list_push(rgui->selection_buf, "Hard GPU Sync", RGUI_SETTINGS_VIDEO_HARD_SYNC, 0);
    rgui_list_push(rgui->selection_buf, "Hard GPU Sync Frames", RGUI_SETTINGS_VIDEO_HARD_SYNC_FRAMES, 0);
+   rgui_list_push(rgui->selection_buf, "Black Frame Insertion", RGUI_SETTINGS_VIDEO_BLACK_FRAME_INSERTION, 0);
    rgui_list_push(rgui->selection_buf, "Estimated Monitor FPS", RGUI_SETTINGS_VIDEO_REFRESH_RATE_AUTO, 0);
 }
 
@@ -1932,6 +1936,24 @@ static int video_option_toggle_setting(rgui_handle_t *rgui, unsigned setting, rg
          }
          break;
 
+      case RGUI_SETTINGS_VIDEO_BLACK_FRAME_INSERTION:
+         switch (action)
+         {
+            case RGUI_ACTION_START:
+               g_settings.video.black_frame_insertion = false;
+               break;
+
+            case RGUI_ACTION_LEFT:
+            case RGUI_ACTION_RIGHT:
+            case RGUI_ACTION_OK:
+               g_settings.video.black_frame_insertion = !g_settings.video.black_frame_insertion;
+               break;
+
+            default:
+               break;
+         }
+         break;
+
       case RGUI_SETTINGS_VIDEO_HARD_SYNC_FRAMES:
          switch (action)
          {

general.h

@@ -159,6 +159,7 @@ struct settings
       unsigned fullscreen_y;
       bool vsync;
       bool hard_sync;
+      bool black_frame_insertion;
       unsigned hard_sync_frames;
       bool smooth;
       bool force_aspect;

gfx/d3d9/d3d9.cpp

@@ -614,6 +614,17 @@ bool D3DVideo::frame(const void *frame,
    dev->SetViewport(&screen_vp);
    dev->Clear(0, 0, D3DCLEAR_TARGET, 0, 1, 0);
 
+   // Insert black frame first, so we can screenshot, etc.
+   if (g_settings.video.black_frame_insertion)
+   {
+      if (dev->Present(nullptr, nullptr, nullptr, nullptr) != D3D_OK)
+      {
+         needs_restore = true;
+         return true;
+      }
+      dev->Clear(0, 0, D3DCLEAR_TARGET, 0, 1, 0);
+   }
+
    if (!chain->render(frame, width, height, pitch, rotation))
    {
       RARCH_ERR("[D3D9]: Failed to render scene.\n");

gfx/gl.c

@@ -1454,6 +1454,11 @@ static bool gl_frame(void *data, const void *frame, unsigned width, unsigned hei
    memcpy(tex_info.coord, gl->tex_coords, sizeof(gl->tex_coords));
 
    glClear(GL_COLOR_BUFFER_BIT);
+   if (g_settings.video.black_frame_insertion)
+   {
+      context_swap_buffers_func();
+      glClear(GL_COLOR_BUFFER_BIT);
+   }
 
    if (gl->shader)
       gl->shader->set_params(width, height,

retroarch.cfg

@@ -89,6 +89,11 @@
 # Maximum is 3.
 # video_hard_sync_frames = 0
 
+# Inserts a black frame inbetween frames.
+# Useful for 120 Hz monitors who want to play 60 Hz material with eliminated ghosting.
+# video_refresh_rate should still be configured as if it is a 60 Hz monitor (divide refresh rate by 2).
+# video_black_frame_insertion = false
+
 # Use threaded video driver. Using this might improve performance at possible cost of latency and more video stuttering.
 # video_threaded = false
 

settings.c

@@ -168,6 +168,7 @@ void config_set_defaults(void)
    g_settings.video.vsync = vsync;
    g_settings.video.hard_sync = hard_sync;
    g_settings.video.hard_sync_frames = hard_sync_frames;
+   g_settings.video.black_frame_insertion = black_frame_insertion;
    g_settings.video.threaded = video_threaded;
    g_settings.video.smooth = video_smooth;
    g_settings.video.force_aspect = force_aspect;
@@ -491,6 +492,7 @@ bool config_load_file(const char *path)
    if (g_settings.video.hard_sync_frames > 3)
       g_settings.video.hard_sync_frames = 3;
 
+   CONFIG_GET_BOOL(video.black_frame_insertion, "video_black_frame_insertion");
    CONFIG_GET_BOOL(video.threaded, "video_threaded");
    CONFIG_GET_BOOL(video.smooth, "video_smooth");
    CONFIG_GET_BOOL(video.force_aspect, "video_force_aspect");
@@ -976,6 +978,7 @@ bool config_save_file(const char *path)
    config_set_bool(conf, "video_vsync", g_settings.video.vsync);
    config_set_bool(conf, "video_hard_sync", g_settings.video.hard_sync);
    config_set_int(conf, "video_hard_sync_frames", g_settings.video.hard_sync_frames);
+   config_set_bool(conf, "video_black_frame_insertion", g_settings.video.black_frame_insertion);
    config_set_int(conf, "aspect_ratio_index", g_settings.video.aspect_ratio_idx);
    config_set_string(conf, "audio_device", g_settings.audio.device);
    config_set_bool(conf, "audio_rate_control", g_settings.audio.rate_control);