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===240p/480i Emulation on a 31kHz CRT Monitor===

Given the many advantages that CRT monitors possess, they make ideal displays for emulation, particularly for 5th-gen games and below. However, to get the most out of them, some extra steps may be necessary. For instance, some games used interlaced modes, which without a shader results in ugly deinterlacing artifacts. Also, even at 480p, games that ran at 240p and below look blocky and pixellated, not to mention correcting the aspect ratio for games using non-square pixels results in scaling artifacts, just as on an LCD. The scaling issues can be dealt with using a superwide 240p resolution, but that requires using 120hz with black frame insertion, and games that use 480i get downsampled to 240p, making it a less than ideal solutionin those cases, although it does have lower latency due lower frame times between vsync.

To fix these issuescorrectly display games that need both 240p and 480i resolutions, the solution lies instead in setting creating a custom superwide 3840x480 modeline, combining it with a shader that scanlines 240p content and interlaces 480i content, and using both through [[RetroArch]], essentially turning your monitor into an extremely sharp CRT TV. On Nvidia cards, the custom modeline can easily be set within your graphics card's drivers. On AMD, it requires the use of third-party software, such as [http://www.monitortests.com/cru-1.1.2.zip Custom Resolution Utility]. Simply add a detailed resolution with the exact settings shown on the picture, restart your computer, and the monitor should now be able to make use of the new modeline. As for the shader, hunterk's [https://github.com/libretro/common-shaders/blob/master/misc/interlacing.cg interlacing.cg] does gives you black lines that will oscillate when given an image with 400 or higher vertical resolution, emulating the trickbehavior of 15kHz displays. There are also some [https://github.com/libretro/common-shaders/tree/master/cgp/tvout%2Binterlacing shader presets] that combine the interlacing shader with tvout-tweaks and image-adjustment for accurate RGB signal emulation and color controls, and also some that utilize Themaister's NTSC shader for composite/s-video emulation.  Once you have the new modeline set and have the shader in hand, open your RetroArch configuration file of choice, set the fullscreen resolution to 3840x480, aspect ratio to 8, and windowed fullscreen to false. Adjust your monitor's image as necessary. It may be necessary to raise your monitor's brightness somewhat, or increase color intensity to deal with the loss of brightness from having pure black scanlines. Some monitors, such as the NEC/Mitsubishi SuperBright series, have settings that increase the monitor's brightness without compromising black level or color temperature significantly.

For CRT monitors, they can use a 120Hz refresh rate to sync to 30kHz (240p) resolutions.However, 240p at 120Hz can create motion blur, due to having twice as many frames being drawn on screen and overlapping. The solution is to draw a black frame every other frame. At 120Hz that essentially brings it back down to proper 60Hz. The issues are that brightness is halved and any frame drops or synchronization issues are very noticeable, so

HoweverIn [[RetroArch]], 240p at 120Hz can create motion blur, due to having twice as many frames being drawn on screen and overlappingthere is an option for black frame insertion in the video options in the menu. The solution is to This makes it draw a an extra black frame for every other frameand it succeeds in making the motion smooth at 120Hz. At 120Hz that essentially brings it back down There is an option to set the vsync swap interval if you want to proper 60Hzdouble frames instead. The issues are that brightness is halved and any frame drops are very noticeable"refresh rate" setting should be set to 60Hz (monitor refresh rate/2) for accurate dynamic rate control in these cases.

In RetroArch there is an option for 120Hz with software inserted black frame insertion in frames has less latency than doing so on the video options in RGUIdisplay's hardware. It also has less latency vs. This makes it draw an extra black frame for every displaying straight 60Hz due to the decreased frame and it succeeds times between vsync in making emulators. It also doubles the motion smooth at 120hz. There is performance requirements of an option emulator to maintain vsync for the swap intervalsame reason, so keep that in mind.