TORONTO -- From boos and catcalls to thunderous applause and standing ovations, premiere screenings like the ones at this week's Toronto International Film Festival can elicit a wide range of audience reaction.

And for the talent behind those films, attending the first-ever public screening can be akin to going into battle.

"You have to know what you are doing and, of course, the risks sometimes are there," says Oscar-nominated filmmaker Werner Herzog, who will be at the Toronto fest with "Salt and Fire."

"It's the same thing like staging an opera in Milano at La Scala. (Maria) Callas was booed and never sang again and (Luciano) Pavarotti was booed and never sang again at La Scala.

"You have to face the gladiators' arena."

The Cannes Film Festival, in particular, is "a blood sport," says Oscar-nominated filmmaker Baz Luhrmann, director of the new Netflix series "The Get Down."

"When I played 'Strictly Ballroom' in the middle of the night at Cannes, I heard two chairs go up. When the chairs go up, by the way ... they spring up and go 'bang,' so you feel like you're being shot at. I thought we were a disaster, but by the end there was a standing ovation and one's life changed.

"However, when I did 'Moulin Rouge,' honestly, there was booing and clapping and there was almost fighting. I think in Toronto, though, it's really simple."

Running Sept. 8 to 18, the Toronto fest is open to the public and often features Q-and-A's with film talent at the end of screenings, adding an air of excitement.

As a result, its audiences tend to be more generous than they are at some other festivals.

"The audience is so with you and they're rooting for you and they want to watch good work, so there's just a really positive energy from the audience," says Drake Doremus, who screened "Equals" at last year's Toronto film fest.

Cannes, by contrast, is largely closed to the public and has mostly industry members in its audiences. That has resulted in some fiercely passionate reactions at screenings, including rapturous standing ovations and loud jeers. (Films booed at the most recent fest in May included Olivier Assayas's "Personal Shopper" starring Kristen Stewart, which will also screen at TIFF.)

"When (booing) happens there, my understanding is that it's generally journalists that are doing it," says actor Viggo Mortensen, noting he was "relieved" when his film "Captain Fantastic" got a standing ovation at this past Cannes.

"There is something about Cannes that ... there's a tradition of the best and worst behaviour, not just from audiences but also from the people who show movies," he adds. "In Cannes, there's something more concentrated about the ugly and the beautiful that happens."

Social media has amplified such extreme reactions, as the writer-director duo behind "Swiss Army Man" found out when it premiered at the Sundance Film Festival in January.

Daniel Kwan and Daniel Scheinert say they thought they'd received a "warm and fun" reception for the quirky dramedy. But the next day, they woke up to headlines claiming there were many walkouts.

"One guy got kind of pissed off at the movie and he was the first one to tweet about it, because he left early and then that was the story," says Kwan.

"I think the Internet blew that thing out of proportion in a really scary, funny way," he adds. "It's the big fish story that gets six feet long or whatever."

Mortensen says that's why he only takes festival screenings "with a grain of salt."

"There are the fad, of-the-moment kind of reactions that can be kick-started by one or two journalists and then it becomes the accepted wisdom, or lack thereof, about a particular movie coming out of Toronto or coming out of Cannes or any festival."

Still, many filmmakers embrace such feedback.

"As a filmmaker, focusing on what you did as seen through the eyes of strangers, as a tool, is remarkable," says director Ivan Reitman, noting he cut over half an hour out of "Meatballs" and reshot a bunch of new scenes after it "didn't play very well" during screenings for several studios in Los Angeles.

"Part of the journey of my life, as a storyteller and as a filmmaker, is to learn how to keep my eyes open and fresh, and one of the greatest tools for it is to watch it with other people," he adds. "It's a way of becoming a virgin again, as far as your art is concerned."

"Pete's Dragon" star Bryce Dallas Howard says her father, director Ron Howard, feels the same way.

"When I was a kid, the night that one of my dad's movies would come out, we would get in the family Suburban, all of us, and we would drive from movie theatre to movie theatre to see what the reactions were like," she recalls.

"I think that the trouble of this storytelling business is that sometimes filmmakers or actors or producers or studios shield themselves from honest reactions and that's really damaging. It's not how it's meant to be.

"Going back to live theatre, having a real-time reaction is essential for feedback."