[plesken]

@popcornmix - I've written a long ago patch which recognized half/full sbs and half/full top bottom.
The part of patch:

Code:

...
+  else if (setting.id == VIDEO_SETTINGS_3D_MODE)
+  {
+    g_guiSettings.SetInt("videoscreen.mode3d", (RENDER_STEREO_MODE)m_Video3DMode);
+    g_graphicsContext.SetStereoMode((RENDER_STEREO_MODE)m_Video3DMode);
+    
+    if (g_graphicsContext.GetStereoMode() == RENDER_STEREO_MODE_SPLIT_VERTICAL)
+    {  
+      if (g_renderManager.GetAspectRatio() >= 3)
+      {
+    g_settings.m_currentVideoSettings.m_CustomPixelRatio = (float)((g_renderManager.GetAspectRatio() / 1.7778) * (float)pow((1.7778 / g_renderManager.GetAspectRatio()), 2));
+    g_settings.m_currentVideoSettings.m_ViewMode = VIEW_MODE_CUSTOM;
+    g_renderManager.SetViewMode(VIEW_MODE_CUSTOM);
+    UpdateSetting(VIDEO_SETTINGS_PIXEL_RATIO);
+      }
+      else if (g_renderManager.GetAspectRatio() < 1) {
+    g_renderManager.SetViewMode(VIEW_MODE_STRETCH_16x9);
+      }
+      else
+      {
+    g_renderManager.SetViewMode(VIEW_MODE_NORMAL);
+      }
+    }
+    else if (g_graphicsContext.GetStereoMode() == RENDER_STEREO_MODE_SPLIT_HORIZONTAL)
+    {
+      if (g_renderManager.GetAspectRatio() >= 3)
+      {
+    g_settings.m_currentVideoSettings.m_CustomPixelRatio = (float)((1.7778 / g_renderManager.GetAspectRatio()) * (float)pow((g_renderManager.GetAspectRatio() / 1.7778), 2));
+    g_settings.m_currentVideoSettings.m_ViewMode = VIEW_MODE_CUSTOM;
+    g_renderManager.SetViewMode(VIEW_MODE_CUSTOM);
+    UpdateSetting(VIDEO_SETTINGS_PIXEL_RATIO);
+      }
+      else if (g_renderManager.GetAspectRatio() < 1) {
+    g_renderManager.SetViewMode(VIEW_MODE_STRETCH_16x9);
+      }
+      else
+      {
+    g_renderManager.SetViewMode(VIEW_MODE_NORMAL);
+      }
+    }
...

This code resize full sbs to half sbs. I think the better way is separate half picture 1920x1080 (left and right) from 3840x1080 and switch to hdmi frame pack 1920x2205.
Maybe you think it over and add this functionality to omxplayer.