The crowd outside designer Giorgio Armani's new shop on the Via Durini is so deep it spills off the sidewalk into the street. Cars are stuck bumper to bumper in a massive jam. Everyone wants to catch a glimpse of Armani's clothes for spring. Italy's top designers have just finished their shows of ready-to-wear fashions during a week of presentations, most of them held at the Milan fairgrounds.

Now it's the buyers' turn to decide if the new trends will appeal to their customers. The emphasis for spring includes shorter lengths, bright colors (after many seasons of beiges, browns and tans), softer shapes and wider use of leather and suede.

Armani, Gianfranco Ferre and the Missonis are among the strongest hitters this season. A visit with each found them reviewing their new designs, appraising the reactions and already thinking ahead to fall, 1982.

At his Milan office, Ferre is about to study videotapes of his much-cheered show to observe the things that worked well and those that didn't. He is sitting on a black leather quilted sofa in a conference room with huge blowups of Italian magazine covers on the wall. Ferre is nervous. His index finger is clenched between his teeth. Now other fingers tug at his beard. He is rocking at the edge of the seat as he waits for the snow and the lines on the television set to clear, and the show to begin.

Up comes a Sousa march, and Ferre sailors come down the runway on the television screen. Girls in navy leather jackets with collars that look like big white Lifesavers, or with loose collars that look like towels casually tossed around the neck . . .Middy blouses in white organdy with huge cotton pique' collars worn with short pants or skirts . . . More white blouses but long enough to be used as above-the-knee-length dresses . . . Bright rugby-striped taffeta shirts with white collars . . . Similarly striped shirts long enough to be used as midcalf-length culottes with silver sequin top and organdy collar . . . Bathing suits, resembling signal flags dipped in sequins.

Ferre begins to nod approvingly. He loves his nautical theme. "I've always been fascinated with navy books. I was never in the navy but the navy spirit makes the women look strong, don't you think?" he asks, testing for a response. He grins when a model in a print of the ship the Normandie is shown on the runway.

Ferre-designed pants are cut full to appear like skirts, all rising above the waist. "Most women have no trouble at the waistline; it is below that is difficult," he says. Other pants have spiral seaming that gives them a roundness. The spiral pants, the striped taffetas, the elegant navy suits . . . Ferre thinks they are the hits of his collection. He likes them because they are big and clean, not slim and tight to the body.

"We cannot go back to things that have been done before," he says. "We are coming to the end of a century. Clothes must be strong and new. Ruffles are not new."

On the videotape, the models march from the runway with a men's chorus singing "We're the Navy." Ferre moves to the edge of his seat again. On the screen, a model darts among the marchers and brings Ferre down the runway. On the runway, the designer puts his hands over his face, then catches his tears of happiness under his glasses with his fingertips.

As he watches the scene, Ferre begins weeping again. "Yes, it is nice," he says. "Now I can say I like it." He smiles. "When you finish a collection, you have more energy to work. I must go now." And he walks quickly down a hallway to an office and closes the door. He will start selecting colors for his next collection.

Giorgio Armani hardly notices the great crowd surrounding him. Like a child in a candy shop, he is enjoying all the goods, gleefully snatching clothes off hangers and trying them on. A padded duffel coat, a leather bomber jacket, lined motorcycle mittens. They are the comfortable kind of clothes he likes to wear. He has restyled them and produced them in huge volume. "Now the young people know that I don't design only for the rich," he says. At one point, he gathers up one of almost everything in the shop, bright colors predominating, and steps into the window to redress the mannequins.

"I wanted to show that I could do something more than blazers and in something other than no-color colors," says the designer, who is wearing a navy sweatshirt, khaki trousers and tan buckskin shoes.

To make sure that buyers get a good look at his spring collection, Armani took down the teahouse he used to show off his Japanese-inspired collection for fall and constructed a labyrinth of steel bars from which he has hung his designs under spotlights.

His Bermuda shorts, now almost a uniform on stylish women here, are softer and wider for spring. "No Marilyn Monroe blown-up skirts," he laughs. "The winds blow and nothing happens." There are also pants as long as the ankle, and long and short skirts in the collection.

Tops are all soft and loose overblouses, often anchored with belts that wrap over the hips. "Somehow, things that tuck in look old," says Armani assistant Gini Ahladeff.

What seems to please Armani the most are the bright, strong colors, like the clear colors of Thai silk. This is a change for Armani. "I had second thoughts," admits the man who lives with no color in his Milan apartment and country house.

"It is difficult to do strong colors without looking vulgar," he says, looking for, and getting, the compliment that he has succeeded.

He builds color with trompe l'oeil effects -- vests that are really attached to jackets, and double sleeves that are really from one shirt. He uses them as opportunities to add more color.

Prints are borrowed from Amish quilts and, on textured fabrics, give added depth.

Armani would like to add some things for the home. "The perfect soap dish that doesn't show leaky soap," he says. Or maybe the perfectly dressed toothpaste? "Crest in a khaki box," he says, laughing.

Rosita Missoni has been out in her garden, collecting chestnuts and picking salad greens and mushrooms for a buffet luncheon for buyers. They are due shortly in Sumirago, an hour from Milan, to buy the Missoni knitwear collection. Like the designing, the selling is a total family effort, with husband, Ottivo, and the three Missoni children joining in.

Buyers actually started arriving at the nearby factory, where all the knitwear is made, more than 10 days before the collection was shown. And they haven't stopped coming.

In the collection there are short skirts similar to tennis skirts, culottes, knickers and jogging pants. But the Missoni winners, as always, are the knitted cardigans in intricate patterns and distinct color mixes. Some of these can be reversed to raincoats.

And this year there are more woven fabrics than before. "I had so many bad surprises watching women grow into their clothes and the clothes grow with them," says Rosita Missoni, whose strong, handsome face looks as though it belongs on a Roman coin. "I said to my family, 'We have to do something.' And now, with the woven fabric, women will know if they have gotten bigger."

The knits, the heart of the collection, are made by some 200 workers in the factory the Missonis built in the town 10 years ago. Two years later they added the house for themselves and then two other houses for the children.

The inspiration for two new patterns this year came from the stripes of animals and from an aerial view of a garden.

"Nothing is born from nothing," says Rosita Missoni.

Her hardest design this year, she says, was the Missoni perfume introduced recently. "For me, visual choices are easy. I can decide quickly on a color or shape."

Her daughter, Angela, collected more than 500 perfumes, and slowly they pared away what they didn't like. "I worried that I didn't like any of them," says Rosita. "One fragrance I thought I liked I put on a scarf, and after an eight-hour trip I hated it," she says. "Finally it came and the nightmare was over."

She plans another fragrance, for men, but adds, "In comparison, designing a collection is almost simple."