On the movie screen, the silver, goosenecked vase crammed with lilac rhododendrons appears to creep closer and closer to the audience. The projectionist, Frederick Weck, methodically encourages the image forward as the shrill and throaty sounds of his contemporary music rise and fall from the instruments played by the musicians on stage.

The scene: Weck at work. The work on view: "Refractions," an art and music composition recently performed at the Corcoran Gallery of Art by the Contemporary Music Forum, a group of area musicians dedicated to composing and performing contemporary music.

Among the groups's most enthusiastic members is Weck, a middle-aged man with an impish grin and a fondness for cardigan sweaters, baggy trousers and free-form music.

But the composer says his work has been limited over the years by the struggle to buy and maintain the paraphernalia of his art-musical instruments, film projectors and tape recorders-and, occasionally, to hire dancers.

He jokingly laments that he once refused his wife's offer to support him so that he "could sit home and just do music." The problem was "I didn't want to change diapers." (The Wecks have three children).

Throughout it all, the music has survived.

There are only a certain number of people who will do music like this," Weck says. "You're not going to jam the Kennedy Center Concert Hall with it. But the fact that there are three groups that have survived (in the Washington area) and that have their own audiences is something. Every day is a struggle. Perhaps we're masochists."

The Contemporary Music Forum's effort to survive on volunteer labor and grants has continued eight years, Weck said. In those eight years, the group has performed more than 100 pieces, including "Refractions," written by Weck and first performed by the forum about two years ago.

He now is composing an electronic music composition for the Easter vigil service April 14 at the National Shrine of the Immaculate Conception. A sound system will be rigged at each corner of the church ceiling to enhance the effect.

"My biggest problem is to get enough wire. Then what do you do with the wire after it's done? Weck asked. "Sell it to the telephone company?"

Aside from his contemporary music, Weck, a music composition graduate of Catholic University, supervises the instrumental music program for the Archdiocese of Washington. During the past 18 years, his open-door poliy to "take everbody" into the program has developed the Catholic school band system from a six-school department into a major program.

Presently 48 schools, representing 3,000 students, are involved in band programs in the District, Montgomery, Calvert and Prince George's counties.

In recent years, the Washington Archdiocesan Music Program has earned top honors from the National Catholic Band Masters Association.

"Instrumental music education is the best education a child can get," Weck said. "It involves the physical and the mental part(of a person) and teaches them to stick to it. They have to learn to work as a group as well as alone. And by putting time and effort into a project, they learn they can accomplish something-because they all sound horrible when they start."

Weck's own musical pursuits began at age 10, playing the trombone with an elementary school band in Camden, N.J.He later won a high school music scholarship, played in the Pennsylvania All-State Band, was first trombonist in the Pennsylvania All-State Orchestra and won a music scholarship to Catholic University.

His serious involvement with contemporary music (as well as photography) began about five years ago, he said. But his love for free-form music goes back much further, he admits with a soft chuckle.

"When I was senior in college a friend of mine, Buddy Prima, Louis Prima's nephew, was also a composition major. We formed a trio, Prima was on trumpet; Earl Kudlick, who subsequently became a dentist, played piano, and I played trombone. that was in 19609"

The group sent an entry tape to the Notre Dame Music Festival and another friend convinced Catholic University to finance the trip, Weck recalled.

"We played one number and they disqualified us because the didn't know what category to put us in," he laughed. "We would play in a different key, different tempo. We had a ball. That was before John Coltrane and all that stuff."

Stan Kenton, one of the judges, encouraged the group to remain for the rest of the festival.Later, Notre Dame gave the trio an award for a special category: "Experimental music." CAPTION: Picture, Contemporary composer Frederick Weck, By Craig Herndon-The Washington Post