Video processing on the CPU is the naive path. It works for small demos, short clips, and a couple of toy filters. It falls apart when the frame size goes up, the frame rate stays high, and every effect wants to touch every pixel. A single 4K frame has more than 8 million pixels. At 60 frames per second, the system is looking at almost 500 million pixels per second before blur, color correction, transforms, scopes, motion analysis, or export enter the picture. That is too much per-pixel work to treat JavaScript on the CPU as the main processing engine. Video processing is mostly the same operation repeated across millions of pixels. That is GPU work. The project this article is based on takes that idea seriously: decode the video in the browser, hand each frame to WebGPU, and keep the expensive work on the GPU for as long as possible. The result is a local-first video processing lab built around WebCodecs and WebGPU.…