Nobody can ring the piracy alarm louder than Jack Valenti. And nobody can do it so eloquently.

Imagine, he says, Hollywood making its movies available legally over the Internet. “I see this as a resplendent, corruscatingly brilliant way of delivering movies!

“But we have to deal with this piracy problem. It stands like a giant, elephantine beast that’s hunkered down in the middle of the highway and we have to get around it.”

The Motion Picture Assn. of America topper has been issuing piracy warnings since 1983, but the difference between digital piracy and analog “is like the difference between lightning and a lightning bug.”

VHS piracy costs showbiz at least $3 billion annually, and digital hacking could explode since it’s much easier. On the Internet, 500,000 films are being illegally downloaded every day, the exec says.

As the exec sits in his Majestic suite, in a pink polo shirt and charcoal pants, one just has to mention the word “piracy” and Valenti is off and running.

“Napster was a wakeup call for us. It showed how you could pillage an entire industry.”

And there’s no point trying to change the subject. Valenti is a man on a mission. The way to call attention to these problems, he says, is to repeat a warning 30 times and it will eventually sink in.

The solution, he says, is technological. Knowing that it affects everything from TV syndication to new blockbuster pics, Hollywood execs have gotten on board; and computer companies, chip manufacturers and consumer-electronics execs, are joining them in the battle.

Keys to a solution are content encryption, watermarking (a mark that limits the reproduction of a film, such as “copy once”) and DRMs. And he’s excited by Movielink.com, in which five majors will offer films that can be downloaded “for a modest fee.”

When Valenti speaks, you believe every word. He is, after all, the man who literally wrote the book on speaking confidently: In June, Hyperion will publish his “Speak Up With Confidence,” which features jacket blurbs of praise from everyone from Warren Beatty to Sumner Redstone.

In his three days here, Valenti is energetically cramming in endless meetings that will tackle everything from the Argentine film industry to French festival problems.

Does Valenti ever get pessimistic about piracy? Does he ever get tired talking about it?

“No, no, of course not!”