With a gravedigger singing the blues, an exiled countess cooking in a homemade solar oven, and about 200 other participants, the Smithsonian Institution will present its 11th annual Folklife Festival, starting Wednesday on the Mall.

Unlike last year's 12-week Bicentennial folklife extravanganza, which attracted about 4 million people, the new festival is scheduled to last just six days, until Monday, Oct. 10. But its underlying purpose will be the same: proiding a showcase - and some prestige - for arts, crafts, cooking and music, which its organizers see as "endangered species" threatened by the waves of popular culture.

Since it started in 1967 the Festival has been part of a national revival of rural and ethnic cultures, and, Smithsonian officials feel, an important impetus for it.

It has also been a part of a blossoming of festivals - in both rural areas and cities - which includes a large street festival today at the Fells Point section of Baltimore.

"It used to be that a lot of these ethnic and rural cultures were things people only did in their basements or someplaces out of the way and private," said Susanne and Reschwalo, a public information officer at the Smithsonian. "But now we've put them in front of a national spotlight. And people feel there's nothing to be ashamed of because they have different accents or eat different foods. We've brought things to Washington and we've brought them respect."

"The Smithsonian carries a sort of cultural Good Housekeeping Seal of Approval," said Ralph Rinzler, director of the museum's folklife program. "By presenting these people with pride on the mall, it makes them feel they have something of value, and it encourages them to keep doing it."

This year is the first time the Folklife Festival is being held in the fall instead of midsummer. On of its main themes will be food, which Roschawlb said is in keeping with the fall harvest-festivals traditionally held in many parts of the world. There will also be a theme of saving energy.

The festival's largest outdoor demonstrations, to be held on the Washing Monument grounds, were arranged by Energy Research and Development Administration (ERDA) as well as the Smithsonian. They are well as the Smithsonian. They are meant to show how old technologies, which Rinzier calls "folk power," were used to prepare food, and can still be used to conserve energy.

Included will be exhibits of roasting salmon over a birchwood fire, New England clambake using heated rocks in a canvas-covered pit, and a smokehouse for curing Virginia hams.

Rinzler said a solar over is being included as a n example of relatively simple modern technology that also saves energy. It will be demonstrated by its inventor, Stella Andrassy, an exiled Hungarian countess whose small laboratory is in her home in Monmouth Junction, N.J.

Washington's own folklife also will be part of this year's festival, with taxi drivers, bartenders, and Capitol guides and elevator operators talking about their jobs and demonstrating their jargon.

Roschwalb said there is a folk culture that is part of almost every job and institution.

"These are things that people don't learn from books or formal studies," she said. "They're traditions and behavior patterns that people learn unselfconsciously and pass on orally. They're informal, but they're very important to the people involved with them."

The budget for this year's festival is just $200,000, compared to the $7.5 million spent last summer, when the festival not only lasted all summer but also included performers from 38 foreign countries.

This year the only foreign participants are a group of musicians from India. The featured state will be Virginia, just a few subway stops away from the mall, and one its featured performers will be John Jackson, a Fairfax County gravedigger who sings blues.

The Virginia exhibit also includes craftsmen making banjos and dulcimers, a gospel choir, a blacksmith, and Jackson's wife, Cora, who will demonstrate making preserves on a 1915 gas stove.

In the African Diaspora section, a regular feature of the Folklife Festivals that will be based outside the Museum of History and Technology, the theme this year will be "street culture." Among its practioners will be street singers from New York and Washington, harmonica players, an accordionist, and a Brazilian band and a Trinidad steel band, both based in Washington.

Besides its usual tents and outdoor stages, the Folklife Festival will make use this year for the first time of the Smithsonian's regular museum exhibits.

For example, trainmen will demonstrate switching maneuvers on a large model railroad set up in the Museum of History and Technology next to an old steam locomotive. Cooks will demonstrate how to make Italian pasta, Jewish matzoh, and Greek phyllo dough in the museum's "Nation of nations" exhibit.

A classroom from an old school in downtown Cleveland, now reconstructed at the History and Technology museum, will be used for discussions by the school's old teachers and students - from 1910 until the 1950s - about school lore and history. The Smithsonian's Roschwalb said topics will include hazing techniques, playground chants and games, what students did to substitutes, and almost everything else that went on in the school but was not taught by teachers.

The festival exhibits will be open from 11 a.m. to 5 p.m., with evening concerts and demonstrations from 8 p.m. to 10 P.m.

Roschwalb said the Smithsonian almost dropped the festival after last year's summer-long effort, but "there was so much public demand," she said, "we had to keep it up."

She said the time was switched from midsummer to take advantage of cooler weather and accommodate groups from schools. The Columbus Day weekend was included, she said, to have Monday (Oct. 10) when families can come too.