Configuring the Open Source Scan Converter for Line Multiplication and Display Compatibility

Your 240p retro console looks soft, flickery, or black on your modern TV because the display expects 1080p or 4K video and your Super Famicom outputs 15kHz. The Open Source Scan Converter fixes that by line multiplying the signal without buffering a full frame, but only if you configure each menu item for your specific TV. This OSSC setup guide walks you through every relevant setting from the Shmups Forum wiki and VGP documentation, explaining what each does to the signal and when to change it.

Before you touch line multiplication, the OSSC must capture a clean digital representation of the video signal. This is the sampling phase setting, and it is the single most common reason a new OSSC owner gets a shimmering, noisy image. The OSSC's ADC samples the signal at up to 170 MHz. If the sampling phase is misaligned, each pixel is sampled at the boundary between two original pixels, producing a soft or ringing image that no line multiplication mode can fix.

Setting the Sampling Phase

Connect your console and display, load the 240p Test Suite by Artemio Urbina, and display the grid pattern. On the OSSC remote, press the Menu button, navigate to System, and then Sampling Phase. Adjust the value while watching the grid. The correct phase is the one where vertical lines appear sharpest with no colour fringing. The OSSC's default is 0, but most consoles require a value between 8 and 16. A bad setting is one that looks acceptable on a static grid but produces shimmer on scrolling games; use the Grid Scroll Test in the 240p Test Suite to verify.

Advanced Timing Tweaker

If your TV still rejects the signal or shows black bars on one edge, enter the Advanced Timing Tweaker submenu. This is where you adjust the horizontal and vertical back porch values to match your display's EDID expectations. The OSSC's wiki documents that the default values work for most HDMI displays, but a 2015 LG TV or a 2020 Sony OLED may require adding 2 to 4 pixels to the H Back Porch to centre the image. Do not change these unless you have a specific problem; the result of getting it wrong is a display that syncs but shows the image shifted left or right.

Your TV refuses to show a picture, or the image cuts out every few seconds. This is almost always an HDMI handshake problem, and the OSSC has two settings that fix it. Navigate to Output Opt. and set HDMI ITC to Auto or On. ITC stands for Information Type Code, a flag in the HDMI stream that tells the TV the content is not a video but a computer or game signal. Some TVs, particularly 4K models from Samsung and LG, apply additional post processing when ITC is absent, adding 10 to 15 milliseconds of lag or refusing the signal entirely.

If the screen still blinks or stays black, change TX Mode from HDMI to DVI. DVI mode strips the audio channel from the HDMI stream, which some TVs interpret as a pure digital video signal they can handle. The tradeoff is that you lose audio over HDMI; you must connect the OSSC's 3.5mm audio output to your TV or sound system separately. This is the standard fix for a TV that accepts a 1080p computer monitor but rejects a 1080p game console.

Scanlines are not a filter. The OSSC generates them by alternating the brightness of output lines to simulate the gaps between scan lines on a CRT. The Hybrid Scanlines mode is the one to use because it only darkens the scanline lines, leaving the lit lines at full brightness. The alternative, Simple Scanlines, reduces the brightness of both lines and looks muddy. Set Hybrid Scanlines to On in the LineX settings menu for the mode you are using.

The Reverse LPF setting controls the Low Pass Filter on the video input. With Reverse LPF enabled, the OSSC applies the filter only to the output, not the input, which preserves the sharp pixel edges that line multiplication produces. Set Reverse LPF to On. The problem case is a display that shows moire patterns on fine checkerboard textures; if you see this, disable Reverse LPF and set the sync LPF to 9 MHz instead.

The OSSC has 15 user configurable slots. Each one stores every setting: line multiplication mode, sampling phase, LPF options, output mode, scanline strength, and advanced timing values. Create one per console. A Super Nintendo at Line5x and a PlayStation 2 at Bob deinterlacing require completely different configurations. To save a slot, press the Menu button, navigate to System, then Save Profile. Select a number from 1 to 15 and confirm. Name it using the on screen keyboard; the name appears on the main menu when you load it.

To load a slot, press Menu, select Load Profile, and choose the one for the console you just connected. The OSSC switches settings instantly. The pitfall is loading a slot for a different input type: if you saved one for a SCART RGB source and then load it while the VGA input is active, the OSSC may not sync. Always save with the correct input type selected first.

Line multiplication is the core of the OSSC. It repeats each input scan line an integer number of times to reach a higher output resolution. No framebuffer is involved, so latency stays below one millisecond. The mode you choose depends on your console's native resolution and your TV's maximum supported resolution.

Line2x and Line3x

Line2x converts 240p to 480p. This is the mode for a TV that cannot accept 1080p over HDMI, or for a capture card that expects a standard definition signal. Line3x converts 240p to 720p. It is useful for a 720p plasma or an older LCD that rejects 1080p. Neither mode is optimal for a modern 1080p or 4K TV because the TV must scale the 480p or 720p image to its native resolution, adding its own lag.

Line4x and Line5x

Line4x converts 240p to 960p. This is the highest integer scale that fits inside 1080p without scaling: the OSSC outputs 1280x960 with black borders. The TV receives a signal it can display without further scaling, which keeps lag at the TV's minimum. Line5x converts 240p to 1080p. This is the optimal mode for a 1080p TV. For a PAL console outputting 288p, Line5x produces 1920x1200, which most 1080p TVs will accept. For a 4K TV, use Line5x and let the TV scale the 1080p image to 4K; the TV's scaling adds lag, but the OSSC cannot output 4K natively. The OSSC wiki documents Line5x as the optimal mode for SNES NTSC, Mega Drive NTSC, PlayStation 1 NTSC, Saturn NTSC, and NES RGB modded NTSC.

The OSSC automatically detects whether the input signal is 240p, 288p, 480i, or 576i, but you must tell it how to process each type. Navigate to the Processing menu. For 240p and 288p, the default is LineX, meaning the OSSC applies line multiplication. Leave this as is. For 480i and 576i, the OSSC offers two deinterlacing methods: Bob and Passthrough.

Bob deinterlacing reconstructs each field by repeating lines, which produces a full frame every field but introduces a vertical bounce on scrolling text. Passthrough sends the interlaced signal to the TV and lets the TV deinterlace it, which may produce combing artifacts if the TV's deinterlacer is slow. For a PlayStation 2 playing 480i games, set 480i Proc to Bob. For a Wii outputting 480i, Bob is also correct. The problem case is a PS2 game that switches between 240p menus and 480i gameplay, such as Gran Turismo 4; the OSSC may take 1 to 2 seconds to relock the processing mode, producing a black screen during the transition.

Allow Upsample2x is a sub setting under LineX mode. When enabled, the OSSC doubles the sampling rate of the input signal before line multiplying, which can produce a cleaner image on certain displays. The OSSC's wiki recommends enabling Allow Upsample2x for Line4x and Line5x modes. The problem case is a display that rejects the signal with Upsample2x enabled; disable it and use standard sampling. This is rare on modern HDMI displays but common on older 1080p projectors.

The OSSC includes a Low Pass Filter on the sync signal and on the video signal. The Sync LPF filters noise on the sync line. Set it to Auto; the OSSC applies the correct filter for the detected input. If you see the image jump horizontally on bright scenes, set it to 9 MHz. The Video LPF filters the video signal before ADC conversion. Set it to Auto. If the image shows moire patterns on fine details, set it to 18 MHz. The pitfall is setting the Video LPF too low, which softens the entire image and defeats the purpose of line multiplication.

You have set Sampling Phase correctly, enabled HDMI ITC, tried DVI mode, and selected Line5x. The screen is still black. The OSSC's wiki documents that some displays, particularly 4K TVs from 2016 to 2018, do not accept 1920x1080 from the OSSC because the OSSC's HDMI output does not include standard blanking intervals. The fix is to use the Advanced Timing Tweaker to reduce the horizontal blanking. Reduce the H Total value by 2 pixels at a time until the TV syncs. A pitfall is reducing H Total too far, which causes the TV to show a distorted image or no image at all. Reset to defaults and try a different line multiplication mode instead.