RY COODER picks his music the same way he chooses his clothes.

In concert, it's not unusual to find him sporting a '40s-style sport jacket over a jaunty Hawaian print shirt, baggy pants and Japanese zori sandals. And his musical wardrobe is even more diverse:

On the radio, he can be heard belting out R&B classics like The Marvelettes' "Beechwood 4-5789" or Ben E. King's "Stand By Me."

At the movies, he created the haunting and historically authentic soundtrack for the recent James-gang epic, "The Long Riders."

On stage, he can run through more R&B, a Blind Alfred Jenkins tune from the Depression called "How Can a Poor Man Stand Such Times and Live," Leadbelly's "Goodnight, Irene," Jim Reeves' country favorite "He'll Have to Go" (developed into a Mexican dance tune) and Elvis Presley's "Little Sister" -- with stops along the way for minstrel show tunes, Burt Bacharach, Jelly Roll Morton and Woody Guthrie.

Someone once observed that "there's something about the way Ry Cooder doesn't write his own songs that makes you wish nobody else did either."

The soft-spoken Californian picked up his eclectic expertise from a life that has been an intriguing musical journey. "Over the years," he says, "I've encountered lots of nice things. There used to be folk festivals, and it was always nice to get together with someone who could do something you didn't know anything about -- usually it's revealing and enlightening. You pick something up for yourself and maybe you give them something they can use. It's a nice trade-off."

As a result, Ryland Peter Cooder is at home on the range of American music, and he's always been willing to dip deep into the mainstream to pull out some peculiar fish. But rather than just reviving forgotten musical forms, Cooder has expanded their charms to encompass his own virtuosity without obscuring their origins. Neither a modernizer nor a musicologist, Cooder is a lover of the spirit at the center of once-popular genres. It's a marriage made in a quarter-century of listening, learning and absorbing -- something old, something new, something borrowed, something blues.

Cooder, who will perform at the Bayou on Wednesday, tours infrequently, keeping a low profile in the Los Angeles area, out of which he has worked for all his 33 years. Yet he has always been a critical favorite and a joy to those who've discovered the wealth of Americana in his nine albums for Warner Bros. Though he's never generated big sales, he has focused attention on a diversity of styles -- zydeco (cajun), Norteno (Tex-Mex), Hawaiian slackkey guitar, and perhaps most importantly, traditional American black music at its climatic '50s juncture of the church and the street.

In the past two years, Cooder has begun to reach a new, larger audience through his evocative soundtrack for Walter Hill's "The Long Riders," and in the next 12 months, his work will be heard in three more film projects.

With almost two decades of playing behind him, Cooder is a little impatient, with the slow pace of fame. "It used to bother me," he admits. "I used to wonder what was wrong, see? But I've learned that it isn't bad and the important thing is to hang in there doing the things that make you happy. If you don't do that, you're going to be miserable no matter how much money you make."

Cooder was born in West Los Angeles in 1947, and picked up his first guitar at the age of 4 (he still has it). He's a largely self-taught musician who traveled around the folk-club circuit watching visiting folk and blues artists like Doc Watson and Sleepy John Estes from a front-row seat. "I got pretty good at remembering stuff," he recalls. "If someone like Gary Davis [an influential folk-blues guitarist] was in town, I'd talk to him, go to where he was staying, give him $5 and get him to play as much as he could while I watched. About a month later I'd find that I started to remember how he did things."

For a while Cooder played in a blues outfit with Jackie DeShannon and sat in with a variety of pickers. "Then around 1964. Taj Mahal showed up in Los Angeles. He was real raggedy and I was raggedy, so we got together and went to the Teenage Fair in Hollywood and sat in a booth for Martin Guitars and just played Delta blues. It was hard and it was good. There were sequined bands with saxophones on either side of us and the Byrds were the big thing, so it was different -- blues at the Teenage Fair. It was far out. That attracted attention and all of a sudden we had a rock group, a blues band . . . a terrible band," he laughs.

It was called the Rising Sons, and it set quickly. But Cooder started to get steady work as a session man in Los Angeles, not only as a guitarist but as a mandolin player (he's credited with almost singlehandedly reviving the blues mandolin tradition). Cooder put in his time with a wide variety of acts, ranging from Paul Revere and the Raiders and Captain Beefheart to Randy Newman, the Everly Brothers and the Rolling Stones. Among his best-remembered but seldom credited solos is the slide work on Little Feat's original "Willin'." Cooder also taught the art of slide to Keith Richard of the Stones.

At about the same time, he did his first film work with legendary producer Jack Nietzsche on the soundtracks of "Performance" and "Candy." He teamed up with Nietzche again two years ago for "Blue Collar" and now finds himself in demand, particularly for period films which can utilize his vast knowledge of the American musical experience. For the "Long Riders," Cooder spent three months researching the period, coming up with authentic (and sometimes authentic-sounding) polkas, square dances, waltzes and other era-evokers.

"It's nice work," Cooder says. "I get to stay home and do it in the house, and it's an excuse to call up strange musicians, which is one thing I like to do a lot. I try to get a handle on what instruments, sound and overall idiom I'm going to establish for the picture and then I put the pieces together."

His current project is a Tony Richardson film. "The Border," starring Jack Nicholson and dealing with illegal aliens in Texas. Cooder plans to use a lot of the indigenous accordian music which he first adopted on his "Chicken Skin Music" album with Flaco Jiminez and the late Gabby Pahinui. "I'm sure going to try to get Falco in on this," Cooder says.

Next up will be another Walter Hill film, "Southern Comfort," set in Louisiana in the '30s -- a perfect vehicle for some Cajun music. And somewhere along the line, Cooder will work with Wim Wenders on his long-delayed film about Dashiell Hammet. "I get to use what I know in a nice way."

One of the threads running through Cooder's music is a fascination with classic R&B. "That music had some of the greatest and most interesting elements in popular music in this country," he explains. "It had something to do with the economic conditions of the people who were doing the music of course, since it reflected where they were socially and economically.

"It came down to soul music being based on church music and all of that has a sense of community. A group of people come up with that sound and they all understand what they're talking about and it's a matter of shared experience and continuity. It's like a brook. You feel the people and see the whole thing. It's very unusual and fun to listen to. I like it a whole lot."

Not surprisingly, given his humanistic views, Cooder finds some modern music technology at odds with his purpose.

In 1978, he became the first major pop artist to record an all-digital album with "Jazz." As recently as October, he was singing the praises of the digital process, comparing it as "the difference between automatic transmission and no transmission." Recently, though, he's done a total turn-about: "Having made two records on digital, I've come to the conclusion that I don't like it as much as I thought I did."

"All the people I know love to make records, to be in the studio. It's very inventive, a laboratory of sorts. So when a new piece of equipment comes along, everybody wants to try it and see what it is. I didn't like the sound of any of my records and I never could figure out why.And then the engineer said digital was going to produce more sound for me. It seemed better than 24-track analog -- clearer and bigger and better sounding."

But Cooder felt the process did something to the sound that he didn't like. "There's a point at which hardware and music don't match up anymore, it gets to be a little too much. Digital is designed to clean up all distortion -- any kind of overlapping and mud and thickness -- to produce the most seperated, totally accurate sound quality possible."

"But here were are sitting out in the studio with our old Fender amps and our beat-up guitars making a pretty much glued-together music that has a lot of distortion built into it. It's simple music and it's small stuff and by the time you run it through the solid-state board and the digital machine, it's been sandblasted.It's bad for the music and so I don't think I'm going to use the digital machine anymore, by golly, I'm going back to tubes and I think I'm gonna like it better. And it's not because I'm nostalgic or an antiquarian. I think the technology is not there for its own sake, it's there to help get the sound on record that you hear in your mind. And that's the trip."

He is equally pessimistic about the influence of radio today. He listened to radio religiously as a child, and remembers it as fondly as the early days of record industry.

"But radio stopped reflecting the people who were out there," Cooder feels. "I don't look at radio anymore as anything I can use. I kind of hate that because I used to listen to it constantly -- that's where I used to hear new music and different kinds of music. And the smaller labels tended to reflect what people were doing regionally." But the past 20 years have seen the industry consolidate, homogenize, go after the universal sound.

"It's bad for the music," Cooder insists. "It weakens things and tends to make people put aside what they knew in the first place." And as the industry exploded and became more complex, "it blew things up a lot bigger than they needed to be. But with the national economy starting to shake, it might occur to some people, especially young people who don't necessarily want to participate in the high finance of the record business, that they can make music to please themselves. And nowadays you can get anything in the world you want on records. But if the public is never going to be aware of that, if radio refuses to play it, well, it seems like a shame to me."

Though Cooder seldom tours in America ("it's too expensive here"), he keeps busy with European and Japanese tours, the film work and the occasional record. He seldom does sessions any more -- largely because his natural "backwards" style of guitar and mandolin playing is out of vogue in the pop studios of the '80s. "But if it's something really strange," he says, "I'll show up for it."

Still, even at home, he learns -- sometimes from unusual sources. His two and half year old son Joachim was recently fiddling with the record player while Cooder's latest album, "Borderline," was playing.

"He sped it up," Cooder says, "and it sounded better. I started listening to why a cut speeded up would change the guitar sound so radically . . . and I began to hear it. I decided to try to get some of this sound effect to come out. I liked it better and I thought 'I'm playing this stuff too slow.' It gave me an idea to speed things up and then maybe some of the musical ideas wouldn't be so ponderous."

Meanwhile, he's touring the United States again, trying to establish a positive relationship with "the audience out there. We can all sit around and play for ourselves, but as soon as you get involved in records, well . . . records are a public medium for everybody and it's kind of aggravating to see the public miss out on something that you think you've done well."