Turbo seek doesn't render the proper frame

[RetroEdit]

More specifically, turbo seek (sometimes? ~~always?~~) renders the frame that immediately precedes the frame that should be rendered. To verify this, one can turbo seek to a particular frame in a movie and examine the visual appearance, then seek to the frame that precedes it and frame advance, and compare the visual appearance to the visual appearance from turbo seeking directly. In my testing, doing these two operations that should appear identical resulted in two different rendered frames.

I discovered this while resyncing an mGBA BizHawk 2.4 movie to BizHawk 2.4.2. One instance of the emulator had turbo seek enabled, while the other didn't. I noticed that the frames appeared different when seeking to equivalent frames. After experimenting with settings, I discovered that the issue is present in both BizHawk 2.4 and BizHawk 2.4.2.