Isn't a 'delay' inherent to digital encoding? I mean, even if the encoding could be done virtually instantly, I seem to recall most of these methods encode diff

Isn't a 'delay' inherent to digital encoding? I mean, even if the encoding could be done virtually instantly, I seem to recall most of these methods encode differences between frames, including some frames ahead of the current one. Since we can't look into the future, you necessarily have at least a few frames delay? Unless there are some efficient digital encoding algorithms that don't need this?