“Perhaps the ballyhoo meant nothing,” Kevin Brownlow wrote in his defining history of the silent film era, “The Parade’s Gone By…”

It’s probably true that even avid moviegoers have increasingly drifted away from the films of what Brownlow called, with good reason, “the richest in cinema’s history.” In 1952, the Sight and Sound poll of critics had seven silents in the top 10 films of all time. The recent, much-debated Sight and Sound list had just one.

In “Babylon,” Damien Chazelle’s feverish and sprawling celebration of those halcyon Hollywood days and their abrupt termination, the director of “La La Land” has, with orgiastic zeal, sought to bring back the ballyhoo.

Yet Chazelle’s three-plus hour extravaganza isn’t the dutiful, nostalgic ode you might expect of such a Tinseltown period piece. It’s much messier and more interesting than that. In resurrecting the silent era and the onset of the talkies, “Babylon,” like Stanley Donen’s “Singin’ in the Rain” before it, has trained its focus on a transitional moment in moving images, painting a picture of how technological progress doesn’t always equal improvement.

Here, in unrelenting excess and hedonism, is the manic, madcap energy of the movies and the crushing maw of the medium’s perpetual evolution. That early freewheeling frenzy is snuffed out (ironically) by the advent of sound and other forces that seek to domesticate the movies. In that way, “Babylon” may be most addressed to our current movie era.

Today’s film industry is similarly wracked by forces of change that may be sapping its big-screen verve. “Babylon” is about how the movies are always reborn, but brutally so. Though it may be a chaotic shamble, Chazelle’s film makes this one point brilliantly clear: Cinema will be tamed for only so long; the parade will go on.

This is, to be sure, not a strictly accurate history. Chazelle has taken a “print the legend” approach to ’20s Hollywood, drawing partly from the pre-code scandals and myths of Kenneth Anger’s “Hollywood Babylon.” His film, a romp and tragedy at once, is sometimes enthrallingly, often exhaustingly played at a manic pitch, careening from set piece to set piece. Striving to impress the wildness of the time, “Babylon” overdoes it, striking a cartoonish over-the-top note from the start, and then, for three hours, trying vainly to sustain its drug-fueled fever dream of bygone Hollywood. That makes for an overstuffed and — especially by the increasingly wayward third act — meandering film.

But it’s also an insistently alive one that’s hard to look away from, with flashes of brilliance. For a director known for more tasteful and sentimental excursions, “Babylon” is a lurid descent into debauchery. Sometimes it’s an unnatural fit. It’s too showy and too long. But Chazelle’s film is something to reckon with, and the kind of ambitious swing that a young director of talent deserves credit for daring.

We start in Bel Air, which in 1926 is almost comically rural. In long groves of trees a fixer named Manny (Diego Calva, an arresting breakthrough) is cajoling workers to help him get an elephant up the hill for a mammoth party to be thrown by a movie mogul (Jeff Garlin). A spot on the guest list (“I heard something about Garbo,” Manny says to a policeman) is all he needs for most favors. In the film’s first opening minutes — an avalanche of elephant excrement that cakes even the camera lens; at the mansion in the hills, a bacchanal of sex and cocaine — exist both the indulgence and grotesqueness of Hollywood.

The party scene seems designed to match or better Martin Scorsese’s “The Wolf of Wall Street” for extravagance. There’s a riff here on the Fatty Arbuckle-Virginia Rappe scandal, but in the heady swirl, the only things that really register are Manny, a Mexican immigrant with dreams of rising in the industry, and Nellie La Roy (Margot Robbie, in an echo of her performance in “Once Upon a Time … in Hollywood”), a young actress trying to break into the movies. She’s sure of it. “You don’t become a star,” she tells Manny. “You either are one or you ain’t.”

In its ecstatic early scenes, “Babylon” throbs with their almost primal showbiz aspirations. “To be part of something bigger,” Manny says. They’re quickly on their way. Nellie is cast as a last-minute fill-in while Jack Conrad (Brad Pitt), a silent star in the Douglas Fairbanks mold, brings Manny along with him the next day to set. Each will make their nimble way up, with a widespread cast of characters swirling around, including a Black band leader (Jovan Adepo), a tuxedo-clad chanteuse named Lady Fay Zhu (a bewitching Li Jun Li) and gossip reporter Elinor St. John (Jean Smart, fabulous).

Nothing is quite as vivid in “Babylon” as its teeming studio of outdoor sets (care of production designer Florencia Martin) where Nellie and Manny each find themselves the day after the party. There is so much more to come after these scenes: the epochal arrival of “The Jazz Singer;” Nellie’s farcical first try on a sound stage; a nighttime dance with a poisonous snake; Jack’s painful slide out of the limelight, followed by his come-to-Jesus moment with Elinor (“It’s bigger than you,” she tells him of the movies); a late misjudged plunge into a dark Los Angeles underworld with a mob boss played creepily by Tobey Maguire; a leap ahead to a 1950s movie theater playing “Singin’ in the Rain.” Some of these scenes (the sound stage, Elinor’s moment) are terrific. Much is overcooked. “Babylon” is never quite rooted in either Nellie or Manny, whose arcs feel increasingly dictated by the film’s real narrative engine, Hollywood history.

But the best of “Babylon” is there, a couple hours earlier, at the carnivalesque Kinoscope lot in the desert. It’s a mad moviemaking nirvana, with films being shot all over and many of the participants women or people of color — a reminder that the early days of film were in some ways more open and inclusive than the Hollywood eras that came later. A Dorothy Azner-like filmmaker directs Nellie, who proves a natural. Up the hill, Manny strives to assist the sprawling sand-and-sword epic that’s desperate to get one last shot before losing the light. “Babylon” is never so exhilarating as when sweat, luck and a chance butterfly conspire to make a moment of movie magic that’s sealed with those divine words: “We got it.”

“Babylon” a Paramount Pictures release, is rated R by the Motion Picture Association for strong and crude sexual content, graphic nudity, bloody violence, drug use, and pervasive language. Running time: 189 minutes. Three stars out of four.