“I want a non-shitty, three-dimensional eulogy,” says Cassie, just after playing out a fantasy funeral in her head in Patricia Rozema’s latest film “Mouthpiece.” It’s a eulogy that no one wants her to give for her mother, with whom she had a bruising argument just before her untimely passing, yet not only is she “the writer in the family,” as her aunt Jane (Paula Boudreau) and father Chris (Ari Cohen) are always quick to tell her before insisting that her brother Danny (Jake Epstein) should take the podium a few days hence, but she appears to be the only one that knows how dynamic her mother was, sharing the experience of being a woman with her as well as blood.

Actually, make that two since co-writers and actresses Norah Sadava and Amy Nostbakken made a shrewd decision when they first created “Mouthpiece” for the stage, conceiving of Cassie as someone split in two by their mother’s premature death, each playing a part of her psyche and fluidly moving between anger and elation, uncertainty and confidence, and above all, grief. What began as a two-woman show in which the main setting was a bathtub becomes a full-fledged fireworks display in the hands of Rosemary, the gifted craftswoman behind such films as “I’ve Heard the Mermaids Singing,” “Mansfield Park” and “Into the Forest,” who uses the prospect of getting into a young woman’s mind as a springboard for all sorts of visual mischief, apt to trap Cassie within a frame through canny camera angles and diffraction in one scene and liberate her with lens flares and vibrant colors in the next.

“I always regret not going farther and I felt this is where we should lose our minds together,” Rozema told the packed house at the Winter Garden Theater in Toronto at the film’s world premiere, and as much as Rozema brings her remarkable eye to “Mouthpiece,” it is her personal experience that proves crucial to the film, fleshing out the role of Cassie’s mother Elaine (Maev Beaty) with Sadava and Nostbakken as a co-writer on the film to reflect the frustrations of balancing parenthood and her professional aspirations. As it turns out, what transpires in “Mouthpiece” isn’t a eulogy at all, but a celebration of the unmediated female voice in all its glory. Following a standing ovation the night before, Rozema spoke about her thrilling new film, which fittingly came about from a tip for her daughter as a good show to see, and taking ownership of her career with a burgeoning production company.

So when you walk into the playhouse at your daughter’s suggestion and you see this, are you actually looking for a project like this, or was this just all serendipity?

No. [laughs] My daughter just proposed it, and I went with a friend, an older straight white guy I’ve been friends with for years. He’s a psychiatrist, and really critical of everything, but he was taken by it, and the play is really confrontational and from a young, fierce, millennial point-of-view about a feminist awakening. So I thought, “I can add the mother’s side [in a film.]. I can add the other generation’s side, and I can add the fact of having lost a mother [myself when I was young] and having a daughter, which they didn’t have.” And [Amy and Norah] loved that amplification of the whole thing. It was a dream. We’re just having a riot now. I found co-creators from a generation earlier.

What’s the dynamic like when you’re throwing around ideas with those two?

The deal was that they would give me a list of groceries to pick up and they would cook, because I’m a shit cook. [laughs] And [we were at] an 800-square-foot cabin right on a lake. There’s something magical about that spot that I love. I love birds, [and what happens there is there are] the murmurations where there’s shapes of starlings in the sky [which] is one of the most beautiful things in the world to me. So we’d watch birds, and talk about our mothers. I would tell stories about things I’ve said to my daughters and about my mother dying, and anything that all three of us responded to, we would just add to a list of scenes about the experience of being a mother, of being a daughter, and then I’d type it up. We would go three or four days, wake up crack of dawn, do it until midnight. We’re all workers. I’d say, “Sing that song again. How did that go again?” Then they’d just be singing a piece.

A lot of the things that were directly from the play, but we cut back quite a bit because they were too theatrical, so we [would] find a cinematic correlative of what they did in the play. Everybody said, “It’s not a film. It’s a play. Patricia, you’re really in trouble.” And I thought, “Why not?” I’ve directed a Beckett play. I’ve worked with Harold Pinter. I love expanding the metaphor to something bigger than photographic replication of reality.

I realize the job is seeing the bigger picture, but with something this disperse, was it more of a challenge than usual?

You’d be surprised how the script is what you did see. There was a bit of restructuring. We brought up the mum’s rejection when she tried to reenter the workforce a little bit sooner, because people needed to connect to her more earlier, and then I added that carousel because it was suddenly the most perfect metaphor for everything. But the rest was edited as planned and my goal is to make it look accidentally beautiful, like, “Oh, my God. It was just tossed off.” I did a film called “Yo Yo Ma: Inspired By Bach,” and that was that style [there] too, but I’ve always loved it. It’s very, very structured, mathematically so, but it looks like it’s jumping from thing to thing. You almost have to be more careful then, because it can feel like a pizza with too many toppings. in the editing, they did come in and I welcomed their input. That was part of our dialogue. I’d say, “Guys, I think we’re getting into pizza here.” And everybody would go, “Oh, shit! It’s pizza.”

Aesthetically, it’s breathtaking and there’s a visual scene sea throughout of division and isolation in the framing even though you present these two actors as one character. What was it like figuring that out?

Bifurcation, we call it, and it was wherever I could create multiples. Wherever I could, like when the mother dies, and Cassie gets the call, it’s through glass and I made sure that Zazu [Myers], the production designer, put that beveled glass in between the rooms, so that I could always shoot through something. You’ll hear a lot of cinematographers say the same thing, but shooting through something creates depth and to extend that idea, often art is in what you don’t see. On a big old network TV show is like, you see everything. Everything’s lit, and it’s a big close up on the mouth, but in something that’s a little bit more ambiguous and richer [where] you’re withholding, you’re directing the eye to other places. So we created bifurcation wherever we could, because [the film is] about that division within ourselves.

[It’s called] dual consciousness. They did these tests where they sever the corpus callosum, and [concluded we can be] two people. They found where one person can believe in God, and the other person doesn’t, and that concept is really thrilling to me because I feel like I’m two people. I feel like I’m multiple genders. I feel like I’m a mother, and just wish I could be a mother all day, every day, and I’m feeling guilty right now about my 22-year-old, I wish I had gave her more time right now, but then I’m sitting here with you talking about something that I love – I can’t believe I get to do this job. I can’t believe it! Fuck, I must have done something right! But it’s like I always knew, “Oh, my God. Woman, filmmaker. Lesbian, filmmaker. It’s going to be a while before they accept me.” And I think I was [looked upon] as a bit of a novelty act. There was all the real filmmakers, the white straight dudes, and then there was, “Oh, yeah. Here’s a little bit of a marginal space.”

Given that, did you feel like this came around at the right time for you?

I just felt that this time was coming – that the cat was out of the bag that women are as capable of telling stories as men, and it was probably better for me to stay in Canada because Hollywood conceives movies as a business more than an art, and because business is about recreating successful models, it’s always, by nature, going to be a few steps behind the times. Whereas in a smaller place like Canada, where film is considered an art form, and it’s about adventure and trying new things, playing in the margins rather than trying to dominate the mainstream, I felt like we had a better chance to really play in the way that I wanted to.

And I told [Amy and Norah] “I’m not trying to take this away from you, or make this something you don’t feel good about.” Because I knew they would be the performers. I knew asserting my ego, or stating my superior experience in film was going to be useless, and wouldn’t get the best out of them because they were a voice that I found really exciting – fierce and funny. Those two things together is a thrilling combination to me. [Still] they deferred to me on lots of things [regarding] how to tell the story, and I know it’s a dirty word right now, but I’m an auteur by nature, I think. I need to know that nothing will be on that screen that I don’t love. Even in my subconscious, I am somehow thrilled by it, even if I don’t intellectually understand it.

I knew I had that security [here] because I was a producer. Crucial Things is my new company. And I had final cut. It was never in question with any of my funders, or my co-producers, or them, that this film was directed by me, and a film by. Except that I don’t, did you notice the credits at the end?

Who thought to do that? It’s such a cool gesture.

I wanted to – I did that for my very first film and I’m a bit of a communist/socialist by nature. Then I’m an autocrat too. [laughs] But it’s “a film by,” and I kept that up there because it is a film by all those people. It felt like it captured a spirit of this production. Maybe I’m just a late bloomer or something, but I just felt like I’ve made all these new friends.

Once I know that I’m not going to be strong-armed into something tacky, or irrelevant, or thin, it makes me more open to all of the voices, especially [Amy and Norah’s] voices, because they started it. They had this brilliant idea of two people playing one. That’s the juice. That’s the kernel of this whole thing. So I have full respect. And we just hit it off right away. We made each other laugh – our text threads make me laugh every day. We’re actually planning another one together, because we love each other so much.

You mention a new production company. Did this experience set you on a new path?

I’ve always wanted to [have one]. I was a co-producer on my first three films, then I got away from it as it got bigger. I just got a bit tired of waiting for producers to put my project at the top of their to do list, so this is a new phase for me. I think I’m going to try to work faster. I want to get a Woody Allen-style schedule – not a Woody Allen-style everything else – because I feel like I tried all these different tones. Maybe you’ve heard this before, but there’s the master and the student mentality – the master is working on one thing, and they often peak in their forties, because [when] they master it, then they’re done. The student is always needs to be learning something. They peak later, but then they have all of these tools in their kit, and then they can assemble them and they have kind of a confidence, and I love creating a new sensation that I haven’t before.

It’s also been exciting to be at the premieres of both “Into the Forest” and “Mouthpiece” in recent years because afterwards, you’ll bring up the cast and crew and there’s so many female department heads. I must imagine it’s exciting to be able to build on that as a producer.

Absolutely. I always used to say I like 50/50, because the world is 50% male/female, just a weirdly spectacular fact how that is so consistent. So I have an almost a spiritual belief that’s the proper balance of things. But on this one, it just felt like I was creating the life of a 30-year-old woman, and I’m not a 30-year-old woman, so I wanted people closer to that age range to be doing [Cassie’s] apartment, to be doing her clothes, to be doing her makeup. That just felt like it was going to create a better sense of authenticity. In the past, if a man and a woman were equal, most of the world would go for the man, but on this one, if a man and woman are equal, I go for the woman, just for authenticity.

What was the premiere like for you?

Spectacular. It was a high point in my life. I had my two daughters on either side of me and we were holding hands for most of it. So to feel that kind of family connection, and [I felt] their pride spilling into me, and me just loving them there and the audience was picking up on all the humor that I wasn’t sure people would get. Really, we thought that we were off in our own world, so we thought that people might not like the jokes. And then to feel the emotion, that wave, I really was tearful there at the end. We decided afterwards, I said, “Okay. This is the peak. It’s never going to get better than this. Don’t expect more. Don’t hope for that kind of response ever again.” We may, but it was just thrilling in this moment. It’s like a tiny perfect moment that we can save.

“Mouthpiece” will play at TIFF once more on September 15th at Jackman Hall at 6 pm.