Moiré is a specific kind of visual artefact: a rippling, wavy pattern that appears when a fine repetitive texture in the picture interacts badly with the pixel grid of the camera or the screen. Classic places to spot it: a striped shirt on news anchor, a herringbone tweed jacket, a brick wall at a certain distance, a chain-link fence, fabric mesh, vibrant printed graphics in a wide shot. The pattern in the scene and the pattern of the pixels beat against each other and produce a third pattern that wasn't actually there.
It's a flavour of aliasing — what happens when a sampling system tries to capture detail finer than it can resolve. Unlike random noise, moiré has structure: bands, swirls, colour fringes. It moves when the camera moves, which makes it impossible to ignore even when each individual frame looks "okay". And because it's generated at the moment of capture or at the moment of display, neither encoder choices nor higher bitrate fix it. Anti-aliasing optics in the camera, careful wardrobe choices on set, and avoiding extreme zoom-out shots of fine textures are the actual preventive measures.
For a product team, moiré is mostly a content quality issue rather than a delivery one. Two practical scenarios. User-generated content platforms see moiré on phone-recorded shirts and graphics that's there before any transcoding starts; aggressive denoising in your transcoding pipeline can actually reduce it slightly, but the fix is at capture. Broadcast wardrobe departments maintain "no stripes, no fine herringbone, no high-contrast small patterns" rules for the same reason. If you're producing professional content and seeing moiré, the answer is on set, not in the encoder.
