Function window_function

src/transformers/src/transformers/audio_utils.py:319–379

Returns an array containing the specified window. This window is intended to be used with `stft`. The following window types are supported: - `"boxcar"`: a rectangular window - `"hamming"`: the Hamming window - `"hann"`: the Hann window - `"povey"`: the Pov

(
    window_length: int,
    name: str = "hann",
    periodic: bool = True,
    frame_length: Optional[int] = None,
    center: bool = True,
)

def window_function(
    window_length: int,
    name: str = "hann",
    periodic: bool = True,
    frame_length: Optional[int] = None,
    center: bool = True,
) -> np.ndarray:
    """
    Returns an array containing the specified window. This window is intended to be used with `stft`.

    The following window types are supported:

        - `"boxcar"`: a rectangular window
        - `"hamming"`: the Hamming window
        - `"hann"`: the Hann window
        - `"povey"`: the Povey window

    Args:
        window_length (`int`):
            The length of the window in samples.
        name (`str`, *optional*, defaults to `"hann"`):
            The name of the window function.
        periodic (`bool`, *optional*, defaults to `True`):
            Whether the window is periodic or symmetric.
        frame_length (`int`, *optional*):
            The length of the analysis frames in samples. Provide a value for `frame_length` if the window is smaller
            than the frame length, so that it will be zero-padded.
        center (`bool`, *optional*, defaults to `True`):
            Whether to center the window inside the FFT buffer. Only used when `frame_length` is provided.

    Returns:
        `np.ndarray` of shape `(window_length,)` or `(frame_length,)` containing the window.
    """
    length = window_length + 1 if periodic else window_length

    if name == "boxcar":
        window = np.ones(length)
    elif name in ["hamming", "hamming_window"]:
        window = np.hamming(length)
    elif name in ["hann", "hann_window"]:
        window = np.hanning(length)
    elif name in ["povey"]:
        window = np.power(np.hanning(length), 0.85)
    else:
        raise ValueError(f"Unknown window function '{name}'")

    if periodic:
        window = window[:-1]

    if frame_length is None:
        return window

    if window_length > frame_length:
        raise ValueError(
            f"Length of the window ({window_length}) may not be larger than frame_length ({frame_length})"
        )

    padded_window = np.zeros(frame_length)