keyframe interval

A keyframe is a frame that stores a complete image. Keyframes provide the entire image in the video stream; after that image is provided, incremental changes between related frames are stored (not the entire image). Thus, when the image in the video changes dramatically—for example, when switching between images—a keyframe must be created to mark the location of change. It’s recommended that you allow Compressor to determine the keyframe interval for your output file; however, you can also set the keyframe interval manually.