Function framerate_to_fraction

scenedetect/common.py:126–145

Convert a framerate value to an exact rational Fraction. Detects NTSC-derived framerates of the form ``N * 1000/1001`` (e.g. 23.976 -> 24000/1001, 29.97 -> 30000/1001, 47.952 -> 48000/1001) for any positive integer ``N`` and returns their exact rational representation. Whole-number fram

(fps: "FrameRate")

def framerate_to_fraction(fps: "FrameRate") -> Fraction:
    """Convert a framerate value to an exact rational Fraction.

    Detects NTSC-derived framerates of the form ``N * 1000/1001`` (e.g. 23.976 -> 24000/1001,
    29.97 -> 30000/1001, 47.952 -> 48000/1001) for any positive integer ``N`` and returns
    their exact rational representation. Whole-number framerates are returned as
    ``Fraction(N, 1)``. Other values fall back to ``limit_denominator(10000)`` for a clean
    rational approximation. ``Fraction`` inputs are returned directly without conversion.
    """
    if fps <= MAX_FPS_DELTA:
        raise ValueError("Framerate must be positive and greater than zero.")
    if isinstance(fps, Fraction):
        return fps
    if fps == int(fps):
        return Fraction(int(fps), 1)
    # Invert fps = N * 1000/1001 to recover N, then verify within tolerance.
    base = round(fps * 1001 / 1000)
    if base > 0 and abs(base * 1000 / 1001 - fps) < _NTSC_DETECTION_TOLERANCE:
        return Fraction(base * 1000, 1001)
    return Fraction(fps).limit_denominator(10000)


class Interpolation(Enum):