Stutter is the irregular hitch you get when a frame is missing, late, or repeated. Where judder is a regular unevenness baked into a frame-rate cadence, stutter is an unplanned lurch: a frame the player should have shown on time arrives late, gets dropped, or is held for an extra beat, so motion that should advance by one step instead stalls and then jumps two - sometimes an object even appears to hesitate or jump back for a single beat. It happens anywhere the pipeline must keep a real-time beat: a capture card under load drops frames at the source, an encoder set beyond the hardware's capacity duplicates frames, or a player on a busy device misses a display deadline. The sharp line to draw is that stutter is not rebuffering: rebuffering is when the buffer runs empty and playback fully stalls, while stutter can happen with a full buffer and a perfect network - the frames are present, but one is rendered late. Like judder, it is a temporal fault, so per-frame metrics are largely blind and mean-pooling buries the few affected frames.
