array.py 文件源码

def bytes_to_yuv(data, resolution):
    """
    Converts a bytes object containing YUV data to a `numpy`_ array.
    """
    width, height = resolution
    fwidth, fheight = raw_resolution(resolution)
    y_len = fwidth * fheight
    uv_len = (fwidth // 2) * (fheight // 2)
    if len(data) != (y_len + 2 * uv_len):
        raise PiCameraValueError(
            'Incorrect buffer length for resolution %dx%d' % (width, height))
    # Separate out the Y, U, and V values from the array
    a = np.frombuffer(data, dtype=np.uint8)
    Y = a[:y_len]
    U = a[y_len:-uv_len]
    V = a[-uv_len:]
    # Reshape the values into two dimensions, and double the size of the
    # U and V values (which only have quarter resolution in YUV4:2:0)
    Y = Y.reshape((fheight, fwidth))
    U = U.reshape((fheight // 2, fwidth // 2)).repeat(2, axis=0).repeat(2, axis=1)
    V = V.reshape((fheight // 2, fwidth // 2)).repeat(2, axis=0).repeat(2, axis=1)
    # Stack the channels together and crop to the actual resolution
    return np.dstack((Y, U, V))[:height, :width]