The bug first bit Mirsalis at the 1974 Cinecon Film Festival in New Haven, Conn., where Mirsalis attended a screening of Fritz Lang’s 1929 silent film “Woman in the Moon,” accompanied on piano by Stuart Oderman. Mirsalis says he left the theater entranced by the spontaneous interaction of Oderman’s music and Lang’s images on-screen, and he was determined to learn how to do it. Within a couple of weeks of arriving at North Carolina State as a graduate student, Mirsalis joined the student film committee, and by the end of his first semester, he was programming and playing to silent films.

Mirsalis would close the circle a quarter-century later by composing his own score for the international DVD release of the “Woman in the Moon,” and most recently, he completed music for a new release of Chester M. Franklin’s 1926 Rin Tin Tin film, “Where the North Begins.”

On June 15, Mirsalis will set up shop at the AFI Silver Theatre’s well-maintained Yamaha B3 spinet piano for the Library of Congress’s “Festival of Film and Sound,” a four-day marathon of classic and rarely seen films — several of which have been newly restored — plus screenings, Q&A sessions and lectures.

Over the course of the festival, he’ll provide music for four silent films: Gregory La Cava’s 1926 W.C. Fields vehicle, “So’s Your Old Man” (June 15); John M. Stahl’s 1926 romantic drama “Memory Lane” (June 16); Frank Capra’s 1928 action thriller “Submarine” (June 17); and to close, Frank Borzage’s 1925 tear-jerker, “The Lady,” starring Norma Talmadge (June 18).

And although silent film music was often guided by what were known as “cue sheets” — lists that provided a few bars of well-known tunes timed to certain scenes — Mirsalis’s approach is a blend of popular melodies and classical themes, adaptation and improvisation, interpretation and impulse. Even films that Mirsalis has seen a thousand times can take new shape depending on how he plays along. When the lights go down at the AFI Silver, Mirsalis says he’ll be “as much in the dark as everyone else.”

I spoke to Mirsalis recently from his home outside San Francisco about the fine art of “live cinema.” (This interview has been edited and condensed for clarity.)

Q: What was it about silent films in particular that appealed to you?

A: The best analogy I can use is that some people say they prefer reading the book to seeing the movie, because when you read a book, you can read into it — the way people look, the way they speak. You can interpret it in a different way. Silent films are sort of the same. If you see a title on the screen, there are probably 30 different ways you can read the title. With the music it becomes a different experience, a different art form. The marriage of music and film can be very powerful.

Q: You mentioned in your program notes for the festival that of the 20,000 feature-length silent films, only about 100 have existing orchestral scores. That’s a conspicuously low number. What accounts for this?

A: There’s a simple answer to that: money. If you think about the cost of writing a 90-minute to two-hour piece and assembling an orchestra to perform it. The Russians could do it. Under a dictatorial state, they could just go to Shostakovich and say, “Write a film score,” and he’d do it, which is why the Russians have some great silent scores. But the economics just weren’t there [in the United States]. There are a lot more of what I call “compiled scores,” where you don’t create an entirely original score, but you put various parts together.

Groups like the Mount Alto Motion Picture Orchestra, led by Rodney Sauer, can put together a score for a 90-minute movie in a single afternoon, working from common pieces they take from a vast library of orchestral music. I’ve seen him perform and it’s fun, because if the film is projected a little slower or faster, he has to use hand signals to switch pieces, speed them up or slow them down. I could never do what he does.

Q: Are there particular composers that you draw from as frameworks to build scores?

A: I like the solo piano work of Rachmaninoff, Debussy and Prokofiev a lot. I use some of that. For a lush romance like “Barbed Wire,” I use Rachmaninoff’s “Rhapsody on a Theme by Paganini” for the main love theme. People might say it’s not contemporary — you know, a 1934 piece of music used for a 1926 movie, which doesn’t bother me that much. I’m not a stickler for accuracy. But I steal from other film composers. For swashbucklers, I don’t use Erich Wolfgang Korngold directly, but I do use Korngold-esque music. You can copy a style without copying the notes enough to get yourself into a copyright infringement lawsuit.

Q: The program for the festival sounds like a real workout.

A: Yes, I’m playing four features, a bunch of short films that I don’t even have the complete list of yet, and I think there’s a newsreel I’m supposed to play to. I don’t know what they are — I’ll just make it up as I go along. I’m older now, I’m going through chemotherapy for metastatic prostate cancer, so I don’t have the stamina I once did. But it wouldn’t be uncommon for me to go to a festival and play 18 hours over three days. But you can do it. I’ll manage — I’ll muddle along.

Q: In many ways, the music sounds like a private dialogue between you and the films. Is that an accurate way to characterize how you approach your work?

A: Yes, I think it is. If I play a film three or four times, you’ll hear a different score every time. Sometimes it’s just the mood that hits me. One of Buster Keaton’s earlier films, “Our Hospitality,” I had played several times, and I’d always played it as a comedy and it never really worked for me. A friend of mine invited me to play to “Our Hospitality,” and I thought just to be different, I’d play it as a drama. When I did, I realized that I’d been doing it completely wrong. The movie has funny bits, but it felt deadly serious — it was breathtaking with a powerful score.

But I don’t want people listening to me. In fact, what is usually the biggest compliment I can get is when people come up to me afterward — usually kind of apologetic — and say, “You know, I saw you there at the beginning and then I kind of forgot you were playing!” If you’re sinking in and getting sucked into the film because of the music, then I’ve done my job.

Library of Congress Festival of Film and Sound June 15-18 at the AFI Silver Theatre in Silver Spring. loc.gov/events/film-and-sound-festival.