But in terms of sheer number of registrants, the interactive conference - where a 140-character start-up called Twitter first burst into the social media consciousness in 2007, and a location app titled Foursquare debuted in 2009 - pulls in the biggest numbers, drawing more than 30,000 techies from 57 countries.
With more than 16,000 badge-wearers and 113 screenings, SXSW Film is no slouch either.
"The festival has significant stature," said Andrew Greenblatt of the Philadelphia Film Society. He will be film-hunting on behalf of this fall's Philadelphia Film Festival. SXSW Film, which is heavy on American independent movies, opens Friday with Jon Favreau's foodie movie, Chef, costarring Sofía Vergara, Robert Downey Jr., and Scarlett Johansson.
Boldface names abound.
At SXSW Interactive, National Security Agency leaker Edward Snowden will speak from Russia via teleconference, as will WikiLeaks founder Julian Assange from London. Girls creator Lena Dunham, whose movie Tiny Furniture premiered at SXSW in 2010, will give one keynote and Amazing Spider-Man director Marc Webb another.
"We're a cultural nexus," said SXSW Film programmer Rebecca Feferman. "Between the film and interactive and music [portions], SXSW is the only place you're going to be able to tap into the overlap of those three industries."
SXSW is expanding into two new realms. The film portion has more television offerings, with shows such as Robert Rodriguez's From Dusk Till Dawn: The Series. Also on tap is Cosmos: A Space-Time Odyssey. Its presenter, big-brained social-media celebrity Neil deGrasse Tyson, is giving a talk.
The conference is also introducing SXsports, with guest speakers such United States men's national soccer team head coach Jürgen Klinsmann, and the ESPN tandem of Bill Simmons, founder/editor of the sports blog Grantland, and stat man Nate Silver of the 538 blog. They'll discuss a topic dear to the assembled self-promoting tweeters: "Media and the Personal Brand."
SXsports "hits the perfect parts of our wheelhouse," said Feferman, who developed it as a "convergent" growth area. "It's entertainment, but also culturally impactful, and involves significant developments in technology and innovation."
More than 1,000 panel discussions will take place over the five days of the film and interactive portions. Film sessions include interviews with Robert Duvall, Nicolas Cage, Tilda Swinton, Sean "Diddy" Combs, Ralph Steadman, and Diego Luna. Interactive panels bear titles such as "The Next Steve Jobs May Be From Africa" and "Being Social with Grandma: Social Media for 50+."
"The world is wide," Feferman said. "But, hopefully, we're doing something that is exciting people. Part of our draw is the environment we create is pretty combustible, and people can connect with others they wouldn't normally find."
"SXSW Interactive is a melting pot of technology, business, and media," said Jonah Berger, associate marketing professor at the Wharton School at the University of Pennsylvania. "It's a great place to learn about new ideas, new opportunities, and the exciting new things that are coming in the future." Berger, author of Contagious: Why Things Catch On, will lead a session called "What Drives Word of Mouth?"
Mark Schoneveld, who works at Poptent, the Center City company that connects independent video makers with brands such as eBay and Netflix seeking advertising content, said SXSW Interactive is full of "really cool people from all over the world who work for really interesting companies that you don't expect to meet and drink beer with in one place."
The gathering of all those insiders looking to either be or discover the next big thing creates a massive marketing opportunity.
"SXSW is a giant advertisement," Schoneveld said. "For itself, and all its participants, and the large companies who want to get their product seen through the eyes of everyone . . . ."
The cool and corporate coexist. When not working at Poptent, Schoneveld helms the influential indie music blog "Yvynyl," which he started in Philadelphia in 2007. For SXSW, he's curated a slate of bands at the Hype Hotel for the Hype Machine, the New York Web music discovery service. The cutting-edge acts on his March 13 bill include Future Islands, Dum Dum Girls, and Chet Faker. The event is sponsored by Taco Bell.
Greenblatt of the Philadelphia Film Society, which also programs the reopened Roxy Theater in Center City, hopes to catch 15 to 20 movies at SXSW, which he said ranks just behind Sundance among must-go American festivals.
"The music films are always fantastic and exciting," he said. This year, there are documentaries such as Mateo, about a white mariachi singer traveling in Cuba, and Supermensch, Mike Myers' directorial debut about Shep Gordon, manager of both Alice Cooper and Luther Vandross.
Features include Jimi: All Is By My Side, a Jimi Hendrix biopic. It stars André 3000 and is written and directed by 12 Years A Slave Oscar-winner John Ridley. Frank is a comedy with Michael Fassbender as the singer in an experimental rock band and Maggie Gyllenhaal as a theremin player. In the movie, the band plays SXSW.
"We're looking for films that could potentially play the festival, or play the Roxy or our film series," Greenblatt said. "The mission is to see films and network. And also enjoy Austin, which is one of the most fun cities in the country."