At the tables I seem to play at it appears that villian has a set with top kicker. Ace eight would be a logical starting had here. You called the turn after the board paired. What were you looking to pick up on the river? Maybe a re-raise of about half the pot would have defined your hand on the turn. I don't think that this guy was playing 8 4 but I guess you never know. His bet on the river looks like he doesn't want a call. I think that if i get to this river I call his all in bet. If he has the boat i pay him off.