Live Streaming & Premieres
Keyframe interval
Also called: GOP, GOP length, keyframe frequency
Compression stores occasional full frames and describes everything in between as changes from the last one. The gap between those full frames is the keyframe interval, and it decides how fast a player can join or recover a stream, because playback can only start at a keyframe. YouTube asks for one every two seconds for live ingest and will not accept anything beyond four. Encoders often express the same setting in frames, so at 30fps two seconds means 60. Getting it wrong is a common cause of a stream YouTube flags as unstable or refuses to transcode into every quality option, even when the bitrate looks healthy.