CRT Lab — real-time CRT video processor

A cathode-ray tube degrades a signal in a fixed order: curvature, phosphor mask, scanline, bleed, bloom, roll. The degradation is the picture. Most software takes one stage and calls it a filter. CRT Lab keeps the order. It began inside memphy.co, a site built as a 2010 webcam room, where for one day the entire interface ran under the layer. It came off the public site because it darkened the footage and cost frames the page could not spare. One gesture stayed: press and hold on her screen and a fisheye loupe follows the cursor into the footage. The lab left with everything else.

One fragment shader, one pass. The source is an image, a video, the webcam, a captured browser tab or an animated test card, uploaded per frame with a mip chain so bloom, chroma subsampling and the hologram echo read one texture at different levels. The chain runs from cursor-anchored fisheye and screen tilt through curvature, bezel, line jitter, VHS head-switching tear, five-tap chroma bleed, 4:2:0 subsampling, macroblock banding, bloom, scanlines and an aperture-grille, slot or shadow mask, to grain, light leak, film burn and a previous-frame buffer for datamosh. Bass pumps the bloom, highs spike the aberration. Twenty named presets, Arcade to VHS 1994, are parameter sets over the same shader. Render clip restarts the source at 0:00 and writes an MP4 with its audio muxed through a MediaStream tap, in one pass. With webcam and tab capture as inputs it plays live rather than queuing renders: a club screen, a stream, a test card looping in a room.

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CRT Lab's animated test card under the default preset

The memphy.co clip through the Arcade preset

The memphy.co clip through the Billboard preset

The memphy.co clip through the Grid LED preset

The memphy.co clip through the Hologram preset

The memphy.co clip through the Dissolve preset

The memphy.co clip through the Datamosh preset