Jay and Mark Duplass are unusually upbeat for a pair of indie directors working today. The sibling helmers, who specialize in such DIY comedies as “Cyrus” and “Jeff Who Lives at Home,” are constantly fielding requests from film festivals to speak on doom-and-gloom panels about the dire state of the industry.

“Jay and I don’t share the prevailing opinion right now that indie film is fucked,” says 36-year-old Mark. “We sometimes feel like these guys in a post-apocalyptic world where there are hungry people complaining and bleeding outside, and Jay and I have set ourselves up in a nice little cave …”

“With an endless supply of chicken nuggets and pizza rolls,” adds Jay, who is exactly 39 months older.

These days, the metaphorical cave in question is Jay Duplass’ office, a modest shed behind his house in Eagle Rock, Calif., where he can write, rock or just plain relax. The two brothers sit on a couch beneath an enormous Italian poster for John Cassavetes’ “A Woman Under the Influence,” the foreign title of which simply reads “Una moglie” — or, “A Wife,” a translation that makes Jay chuckle.

Cassavetes is just the sort of patron saint to inspire this duo, who had the good fortune of making their debut feature, 2005’s “The Puffy Chair,” at precisely the moment Panasonic DVX100 came out — the first camera to record decent 24-frame video, in their opinion. That breakthrough meant they could inexpensively produce their brand of intimate, improvisation-friendly comedies and get them seen via Netflix and other on-demand services. (They were early adopters of the format and have reached exponentially more fans that way than in theaters.)

The siblings followed “The Puffy Chair” with micro-budgeted “Baghead” and “The Do-Deca-Pentathlon,” as well as the slightly pricier “Cyrus” for Fox Searchlight and “Jeff” for Paramount. While that resume hasn’t exactly made them household names, the brothers aren’t nearly so obscure now that they play “the midwives” on “The Mindy Project.” Mark in particular does a fair amount of acting, appearing in “Your Sister’s Sister,” “Safety Not Guaranteed” and “Zero Dark Thirty” last year. He recently wrapped a role as Melissa McCarthy’s love interest in “Tammy.”

Mark will also star in the Duplass brothers’ first stab at a TV series, “Togetherness,” which HBO greenlit earlier this month. The switch to television caught the siblings completely off guard. As a rule, Mark says, “We don’t break 90 (minutes),” but the “Togetherness” concept — in which a central couple, a sister and their best friend attempt to live under the same roof — was unique in that it simply didn’t end.

Somewhat sheepishly, they admit they hadn’t been paying much attention to what was happening on television. However, now that they both have young kids of their own and aren’t traveling the festival circuit so much, the brothers have started to appreciate how subtle some of the open-ending storytelling is on TV. And besides, their style — very personal with lots of closeups — lends itself to the smallscreen anyway.

“Mostly what you’re trying to do is provide a challenging narrative — that’s why you’re in independent film, because the mainstream doesn’t want to make it and you can’t get the money,” Mark says. “Oftentimes, for us, that involves challenging protagonists, people who have questionable moral behavior who are maybe more difficult to like in the first 10 minutes.”

But on TV — and HBO in particular — the brothers realized they have time to lure audiences into caring about their characters over the course of multiple episodes or seasons. Instead of having to know where every detail they throw up in the air will land, the brothers are learning how to leave things open-ended.

“It’s great to have that kind of kindergarten-esque growth at this stage in our careers, where we’re learning a whole bunch of new stuff,” Mark says. “They taught us how to juggle 150 balls instead of just three.”

The duo have already mapped out the first two years of the open-ended series, which co-stars Amanda Peet, Melanie Lynskey and Steve Zissis.

“What we talk about with our movies is how to do the subtlest twists that will register, because that’s how we experience life,” Jay says. “Like, when you get some rejection, it’s not yelling and screaming necessarily. It’s usually this tiny thing that if you’re privileged with my world, you know what it means.”

The Duplasses’ sensitivity to such naturalistic details is one of the things that sets their work apart from most megaplex fodder — what Mark calls “our introspective obsession with human behavior and how funny and sad and odd it can be.” It’s also one of the aspects that drew name actors like Jonah Hill, John C. Reilly and Jason Segel to collaborate on their features.

According to Jay, the siblings’ goal is simply to make a body of interesting, unusual work over the course of their careers, though they hope Mark’s name would one day be enough to serve as their own studio. The brothers are also unusually willing to scale their work per the available resources, which is why their attitude is so different from other indie filmmakers, who sorely miss the heyday of multimillion-dollar Miramax movies.

“First, we have something we want to make, and then we figure out how we can make it,” Jay says. “ ‘Baghead’ could have been a giant movie” — with fewer jokes and more slashing — “and we could have made ‘Cyrus’ for $10,000 at our house.”

In hindsight, the brothers realized that “Jeff Who Lives at Home” had been their stab at a detective story, however unconventional, and their other films each play off existing genres as well. Looking forward, they’re pursuing everything from “a trilogy of really expensive movies” to “a whole slew” of $5,000 projects, says Mark, prompting Jay to suggest “a war movie where the worst thing that happens is someone gets their feelings hurt really bad, and the war is way off in the background.”

For Mark, one of the top surprises of working on “Zero Dark Thirty” (he shares scenes with James Gandolfini) was realizing that Kathryn Bigelow’s process was “almost exactly the same” as theirs: “It was a fully lit room, there were three roaming cameras, a premium was put on performance, improvisation was not only allowed but encouraged. We were not there to march the orders of the script and exact them; we were there to discover what the best version of that moment could be.”

Lately, the brothers have surrendered to not knowing who is going to like their movies and why, relieved that audiences can find “Togetherness” on their own terms, whether screening on cable or down the road via HBO Go. They’re also encouraged that Twitter chatter is increasing on “Jeff Who Lives at Home,” which opened more than 17 months ago.

“We are making movies because we had critical emotional experiences in movie theaters growing up,” Jay says. “It moved us; it made us so goddamn happy as human beings. We are trying to return the favor and to be part of that feedback loop” — and they’re completely open to the idea that for the next round of audiences, theaters may not have anything to do with it.