Joe Brooks is stuck on Joe Brooks something fierce. "The talent is there; it's really there," he says of himself, not quite believing the wonderful truth. "People say I should be very quiet about this, but WHY? I do what I do very, very well."

It used to be that even in his own charmingly immodest appraisal, Joe Brooks did only one thing very, very well and that was write commercial jingles. "You're Got a Lot to Live and Pepsi's Got a Lot to Give," being the most prominent. He's won 21 Clios, the ad game's highest accolade, and for what it's worth more people in the United States have listened to his music than any other composer in the world.

Last year, 40-year-old Joe Brooks discovered the feature film. He composed, arranged and conducted the music for as well as wrote, produced and directed a treacly bit of shameless corn called "You Light Up My Life," whose Debbie Boone-sung title song has since won an Oscar, a Grammy and a Billboard notice as the most successful single in the history of popular music. The movie returned an estimated $15 million, and Brooks, whose share of that and the record revenues was something like $3 million, is not one to let the whole experience just amiably slide off his back.

"I love to talk about how everyone turned that song down," he says, genuinely loving it. "When I won the Grammy I could have made the traditional speech about how much I owed to everybody, but it would have been a lie. The fact is, I didn't have any help. So I told them, 'Every firm sitting out there tonight turned down this song.' And everyone applauded."

Success has not made Joe Brooks more modest, it has made him make another film, "If Ever I See You Again," of which he says, not surprisingly, "This is going to be an enormous hit film. Everyone will want to see this film. The title song is going to be a big hit and when it is, I'm going to say, 'I've done it again.' And that's not ego, that's a fact. I guarantee it."

The new film is about a man who discovers that the woman who lights up his life is the woman he felt he wasn't good enough for as a callow college youth, the woman who got away. In honor of the occasion Brooks not only repeats the umpteen tasks he took on in his first feature, but has given himself the starring role as well, presumably leaving no new worlds to conquer in this third feature unless he feels a sudden urge to personally put in the sprocket holes.

Brooks acted in the film, overcoming a stutter in the process, simply because he felt like it. "And I'll tell you something interesting, " he says grinning, "I act well."

Joe Brooks in person is a bit easier to take than Joe Brooks in print, at least partly because his unending self-promotion seems disarming, almost ingenuous, because he is given to flashing a small secret smile which shows he is so excited by it all he is about burst. Still, it is not uncommon for people he meets to be less than taken by him and his claims for present and future greatness.

"People underestimate everything I do because I do it all," is now he prefers to put it. "This has never been done in the history of this business; it's never been done. And people don't want those kind of things because it implies such a big, big, big ego, it's totally out of the question. Do I have that big an ego? Yes, but saying that is different than bragging. I think I can do it all."

Though he says he enjoys working within the Hollywood system, Brooks finds at least equal pleasure in knocking the pillars of same. "The correlation between what the public wants and what the studio heads think they want is zero," is one such blast, along with, "What other industry do you know where the top guys can be wrong 80 percent of the time and still be up there?"

Brooks says such things because he will apparently never forget all the executives who turned him down and because he sees himself as eventually supplanting the tired gnomes of Hollywood and becoming a $100-million-a-year production power. "It's like Jimmy Carter," he explains. "No one saw what he was doing, but he was slowly building up a base and then bango, he was here."

So voluble in other areas, Brooks becomes surprisingly reserved, not to say distant, when asked about how he does it, what quality his films have that all the others somehow lack.

Yes, he will say as often as you like that "I know the pulse out there, what the public wants, don't bet against me because I am them," but he balks at naming any specific common denominators, putting it all down to "instinct." He balks even harder at the suggestion of any similarity with "Benji's" Joe Camp and "Billy Jack's" Tom Laughlin, two other adept purveyors of popular sentiment.

And tell him it's been said that his films are shameless monuments to the pulling out of cliched emotional stops most people have forgotten even existed and the smile will momentarily leave his face. "The people who say that are not the ones who pay," he replies accurately enough. "In Ohio, in Pennsylvania, people are breaking house records. My song was the most successful song in history, that's my answer. Sentimental? I don't know what that word means. I tell people who say my films are like that, 'Just bring your wife.'"

Big kid that he is, that smile never leaves Joe Brooks' face for long, especially when he talks about his interest in life when he tires of the film world: politics.

"I will run for public office because I want to be of help," he says, mentioning a center for children with speech impediments he's starting as well as other charitable ventures. "I want to play politics in four or five years, see what that's kinda like." And if he doesn't win, guess what? "I'll go back until I do."