British actress Rebecca Hall on Saturday described how she drew on her own biracial identity to direct her first film "Passing", as it premiered at this year's online Sundance Film Festival.

Adapted from Nella Larsen's seminal novel, the movie explores "racial passing," as two childhood friends of mixed racial heritage have a chance encounter in 1920s New York while both pretending to be white.

"Vicky Cristina Barcelona" star Hall is the daughter of celebrated British director Sir Peter Hall and Detroit-born opera singer Maria Ewing, whose own father was Black.

"It was something in my family that was always known and not known -- that my grandfather passed for white, and probably his parents were both African-American and passed for white also," said Hall.

After several "evasive" conversations within the family about race, "I started to think about... how I present as this white-passing person, who has all of the privileges and am afforded that because of how I look," she added.

The movie is shot in black-and-white, which Hall said was a "conceptual choice to make a film about colorism... that drains the color out of it."

It swaps the usual widescreen format for a tight 4:3 ratio, reflecting the repression both characters contended with from society and from within, as they try to find their place in the world.

While Irene (Tessa Thompson) is embarrassed by her attempt to "pass," Clare (Ruth Negga) has disguised herself for years, with a wealthy and oblivious white husband but a yearning for her old community.

"I was so crushed by the psychological cost of feeling you have to make a decision to sever yourself from your community, and essentially from one's self, in order to survive," said Negga. "It's a paradox."

The Hollywood Reporter praised Hall's "thoughtful, provocative and emotionally resonant" debut, while others criticized its slow pace, with the Guardian dubbing the film "elegant but inert."

- 'Grotesque ways' -

Also tackling the motif of racial bias from a deeply personal perspective Saturday was the premiere of "Wild Indian."

The film explores the violence and trauma that has stalked generations of Native Americans, through the tale of two young Ojibwe boys who murder a classmate and must confront the truth decades later.

Directed by Lyle Mitchell Corbine Jr., who is Native American, the film depicts violence and alcoholism among its lead characters, but places those behaviors within the context of the childhood abuse and racism they also face.

"For a long time Hollywood has portrayed us in grotesque ways," said Michael Greyeyes, one of the film's many indigenous stars. "I felt safe to reclaim that kind of portrayal... in our terms."

Also starring are Kate Bosworth and Jesse Eisenberg, who said playing a "metaphor... of the upwardly mobile white guy" as glimpsed by Greyeyes' character was a "vital kind of education that Americans should have."

Top US indie film festival Sundance, co-founded by Robert Redford, typically takes place each winter in the Utah mountains, where multi-million-dollar deals are struck for many of the year's most coveted arthouse titles.

Due to the pandemic, all of this year's 72 feature films are making their premieres via online streaming, with the festival ending Wednesday.

On Saturday, Apple announced it had won an intense bidding war for global rights to this year's festival opener "CODA." 

The movie, about a high-school teen who is torn between pursuing a music career and staying home to support her deaf parents and brother, drew a rapturous response from critics at Thursday's premiere.

It reportedly sold for a Sundance-record $25 million.