Hoffman, Letterman honoured in US
The Rain Man actor and the talk show host received this year's Kennedy Centre Honours - the nation's highest award for those who have influenced American culture through the arts - alongside others including rock band Led Zeppelin and ballerina Natalia Makarova.
Obama drew laughs from his guests at the White House when he described the honorees as "some extraordinary people who have no business being on the same stage together".
The president thanked the members of Led Zeppelin for behaving themselves at the White House given their history of "hotel rooms trashed and mayhem all around".
On the red carpet, Letterman said he was thrilled by the recognition and to visit Obama at the White House.
"It supersedes everything, honestly," he said. "I haven't won that many awards."
De Niro saluted Dustin, saying he had changed acting, never took any shortcuts and was brave enough to be a perfectionist.
"Before Dustin burst on the scene, it was pretty much OK for movie stars to show up, read their lines and, if the director insisted, act a little," De Niro said. "But then Dustin came along and he just had to get everything right."