Splitting the difference between SXSW's film and music streams, Oscar-winning director Danny Boyle and longtime collaborator Rick Smith of Underworld held an "in conversation" panel, a good deal of which centered around their first and most famous work, "Trainspotting," which rode the ecstatic wave of dance anthem "Born Slippy," making both '90s cultural touchstones.

"We were doing pretty well as an underground dance band in the U.K.," recalls Smith, "and we would get a call once a week, 'Can we use your music in X film or TV program?' Every time it would be like, 'What's it for?' They'd say, 'A violent, drug-dealing, death, mayhem scene in a nightclub.' For us, that was horrible. We hated it. The [rave] culture that we were a part of felt safe, felt so positive, this was not what we were interested in.

"So we got a call from Danny. What's it about?' It's heroin addiction? God, here we go again.' Then Danny said, 'Come along and I'll show you 15 minutes.' [We saw] the humour, the intelligence and the compassion of it and at the end of the clip, it became the complete opposite: 'You can use anything of ours that you want in your film.'"

Boyle noted that his coming of age music was late-'70s punk, but that by the time he started making movies at age 35, "rave, what you guys call electronic dance music, culture started and I was just about old enough to go along there without embarrassing myself."

So both Boyle's "Shallow Grave" and "Trainspotting" have electronic dance music in them. The first one is dominated by a group called Leftfield, while the second is dominated by Underworld. And although the book is about heroin addiction, the actual film is really about dance culture — and a different drug, which was ecstasy — so there's a different spirit in it.

"We did that unapologetically," Boyle adds, "because it was a challenge to make a drug movie that you can watch, because most of them were just unwatchable, they were so depressing. If you're going to do heroin accurately, someone takes it, then maybe they throw up and go sit in a corner for, like, 10 hours. It's not very cinematic. So it's rarely a film about a different drug mentality. The rhythm of the film can be expressed with a different [musical] tent pole rather than the drone of heroin."

"That's why the music of 'Trainspotting,' you can track from early punk right through to electronic dance music, best expressed by Underworld at that time and then Brit-pop which was taking off at that time as the next musical movement in Britain."

As much as Boyle was feeling inspired by Underworld's music, the dance group was felt the same kinship to his art form.

"Film mattered a lot to me in my music career. People who know Underworld's music know there's a really filmic quality," Smith says, crediting "the realization I could paint filmic pictures, as well as moving people's bodies."

Oh, and while "Trainspotting" and its soundtrack are now considered timeless classics, Boyle points out that this wasn't always the case when they came out.

"We did get attacked that the films were too MTV, but I considered that a compliment at the time. I didn't see it as a criticism. They said we just strung a bunch of pop videos together, but no, that's the language. People are living their life like that now. I do. I see my life in pop music."