1 files changed, 121 insertions, 0 deletions
diff --git a/rust/crates/time/src/frame_rate.rs b/rust/crates/time/src/frame_rate.rs
new file mode 100644
index 00000000..7af10649
--- /dev/null
+++ b/rust/crates/time/src/frame_rate.rs
@@ -0,0 +1,121 @@
+use serde::{Deserialize, Serialize};
+
+use crate::media_time::TICKS_PER_SECOND;
+
+#[cfg_attr(feature = "wasm", derive(tsify_next::Tsify))]
+#[cfg_attr(feature = "wasm", tsify(from_wasm_abi, into_wasm_abi))]
+#[derive(Serialize, Deserialize, Clone, Copy, Debug, Eq, PartialEq)]
+pub struct FrameRate {
+    pub numerator: u32,
+    pub denominator: u32,
+}
+
+impl FrameRate {
+    pub const FPS_23_976: Self = Self {
+        numerator: 24_000,
+        denominator: 1_001,
+    };
+    pub const FPS_24: Self = Self {
+        numerator: 24,
+        denominator: 1,
+    };
+    pub const FPS_25: Self = Self {
+        numerator: 25,
+        denominator: 1,
+    };
+    pub const FPS_29_97: Self = Self {
+        numerator: 30_000,
+        denominator: 1_001,
+    };
+    pub const FPS_30: Self = Self {
+        numerator: 30,
+        denominator: 1,
+    };
+    pub const FPS_48: Self = Self {
+        numerator: 48,
+        denominator: 1,
+    };
+    pub const FPS_50: Self = Self {
+        numerator: 50,
+        denominator: 1,
+    };
+    pub const FPS_59_94: Self = Self {
+        numerator: 60_000,
+        denominator: 1_001,
+    };
+    pub const FPS_60: Self = Self {
+        numerator: 60,
+        denominator: 1,
+    };
+    pub const FPS_120: Self = Self {
+        numerator: 120,
+        denominator: 1,
+    };
+
+    pub const fn new(numerator: u32, denominator: u32) -> Self {
+        Self {
+            numerator,
+            denominator,
+        }
+    }
+
+    pub const fn is_valid(self) -> bool {
+        self.numerator > 0 && self.denominator > 0
+    }
+
+    pub fn as_f64(self) -> Option<f64> {
+        if !self.is_valid() {
+            return None;
+        }
+
+        Some(f64::from(self.numerator) / f64::from(self.denominator))
+    }
+
+    pub fn frame_number_upper_bound(self) -> Option<u32> {
+        if !self.is_valid() {
+            return None;
+        }
+
+        Some(self.numerator.div_ceil(self.denominator))
+    }
+
+    pub fn ticks_per_frame(self) -> Option<i64> {
+        if !self.is_valid() {
+            return None;
+        }
+
+        let tick_numerator = TICKS_PER_SECOND.checked_mul(i64::from(self.denominator))?;
+        let tick_denominator = i64::from(self.numerator);
+        if tick_numerator % tick_denominator != 0 {
+            return None;
+        }
+
+        Some(tick_numerator / tick_denominator)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::FrameRate;
+
+    #[test]
+    fn resolves_ticks_per_standard_frame_rate() {
+        assert_eq!(FrameRate::FPS_23_976.ticks_per_frame(), Some(5_005));
+        assert_eq!(FrameRate::FPS_24.ticks_per_frame(), Some(5_000));
+        assert_eq!(FrameRate::FPS_25.ticks_per_frame(), Some(4_800));
+        assert_eq!(FrameRate::FPS_29_97.ticks_per_frame(), Some(4_004));
+        assert_eq!(FrameRate::FPS_30.ticks_per_frame(), Some(4_000));
+        assert_eq!(FrameRate::FPS_48.ticks_per_frame(), Some(2_500));
+        assert_eq!(FrameRate::FPS_50.ticks_per_frame(), Some(2_400));
+        assert_eq!(FrameRate::FPS_59_94.ticks_per_frame(), Some(2_002));
+        assert_eq!(FrameRate::FPS_60.ticks_per_frame(), Some(2_000));
+        assert_eq!(FrameRate::FPS_120.ticks_per_frame(), Some(1_000));
+    }
+
+    #[test]
+    fn rejects_invalid_or_unsupported_rates() {
+        assert_eq!(FrameRate::new(0, 1).ticks_per_frame(), None);
+        assert_eq!(FrameRate::new(1, 0).ticks_per_frame(), None);
+        assert_eq!(FrameRate::new(7, 3).ticks_per_frame(), None);
+    }
+}