Did Heath Ledger base his Joker performance on this 1979 interview with singer Tom Waits?

From toplessrobot, This video of a 1979 interview with singer Tom Waits has been making the round, as it is almost assuredly what Heath Ledger based his performance as the Joker on in The Dark Knight. The voice, the mannerisms -- pretty much everything but the lip-licking, really. Of course, the other possibility is that Tom Waits is a time-traveler, and did this interview after watching a Dark Knight matinee.