Fix video recording with frame skip enabled.

When we skip frames, we just don't draw them on our frontend. The
function `systemDrawScreen` also send the video frames to be recorded,
but only when called from the core.

Our solution creates a auxiliary `systemSendScreen` that only adds the
frame to the recording. It is called when the core decides to skip a
frame. This way we can get the video frame for recording, just like
audio ones are always sent.

src/System.h

@@ -50,6 +50,7 @@ extern bool systemPauseOnFrame();
 extern void systemGbPrint(uint8_t *, int, int, int, int, int);
 extern void systemScreenCapture(int);
 extern void systemDrawScreen();
+extern void systemSendScreen();
 // updates the joystick data
 extern bool systemReadJoypads();
 // return information about the given joystick, -1 for default joystick

src/gb/GB.cpp

@@ -5059,8 +5059,10 @@ void gbEmulate(int ticksToStop)
                                         ticksToStop = 0;
                                 }
                                 gbFrameSkipCount = 0;
-                            } else
+                            } else {
                                 gbFrameSkipCount++;
+                                systemSendScreen();
+                            }
 
                             frameDone = true;
 
@@ -5211,6 +5213,8 @@ void gbEmulate(int ticksToStop)
                                 if (systemPauseOnFrame())
                                     ticksToStop = 0;
                             }
+                        } else {
+                            systemSendScreen();
                         }
 
                         gbFrameCount++;

src/gba/GBA.cpp

@@ -3884,8 +3884,10 @@ void CPULoop(int ticks)
                             if (frameCount >= framesToSkip) {
                                 systemDrawScreen();
                                 frameCount = 0;
-                            } else
+                            } else {
                                 frameCount++;
+                                systemSendScreen();
+                            }
                             if (systemPauseOnFrame())
                                 ticks = 0;
 

src/libretro/libretro.cpp

@@ -1704,6 +1704,10 @@ void systemDrawScreen(void)
     video_cb(pix, systemWidth, systemHeight, pitch);
 }
 
+void systemSendScreen(void)
+{
+}
+
 void systemFrame(void)
 {
     has_frame = 1;

src/sdl/SDL.cpp

@@ -1649,7 +1649,7 @@ int main(int argc, char** argv)
             sprintf(tmp, "%s.ups", filename);
             patchNames[patchNum] = tmp;
             patchNum++;
-			
+
             // no patch given yet - look for ROMBASENAME.bps
             tmp = (char*)malloc(strlen(filename) + 4 + 1);
             sprintf(tmp, "%s.bps", filename);
@@ -2020,6 +2020,10 @@ void systemDrawScreen()
     }
 }
 
+void systemSendScreen()
+{
+}
+
 void systemSetTitle(const char* title)
 {
     SDL_SetWindowTitle(window, title);

src/wx/panel.cpp

@@ -2390,15 +2390,10 @@ static const wxString media_err(recording::MediaRet ret)
     }
 }
 
-int save_speedup_frame_skip;
-
 void GameArea::StartVidRecording(const wxString& fname)
 {
     recording::MediaRet ret;
 
-    // do not skip frames when recording
-    save_speedup_frame_skip = speedup_frame_skip;
-    speedup_frame_skip = 0;
     vid_rec.SetSampleRate(soundGetSampleRate());
     if ((ret = vid_rec.Record(fname.mb_str(), basic_width, basic_height,
              systemColorDepth))
@@ -2416,8 +2411,6 @@ void GameArea::StartVidRecording(const wxString& fname)
 void GameArea::StopVidRecording()
 {
     vid_rec.Stop();
-    // allow to skip frames again
-    speedup_frame_skip = save_speedup_frame_skip;
     MainFrame* mf = wxGetApp().frame;
     mf->cmd_enable &= ~CMDEN_VREC;
     mf->cmd_enable |= CMDEN_NVREC;

src/wx/sys.cpp

@@ -72,6 +72,14 @@ void systemMessage(int id, const char* fmt, ...)
     wxLogError(wxT("%s"), wxString(buf, wxConvUTF8).c_str());
 }
 
+void systemSendScreen()
+{
+#ifndef NO_FFMPEG
+    GameArea* ga = wxGetApp().frame->GetPanel();
+    if (ga) ga->AddFrame(pix);
+#endif
+}
+
 static int frames = 0;
 
 void systemDrawScreen()