Deoldify Vapoursynth filter

[Dan64]

good!

Unfortunately it seems that there is something wrong with Average Frames.

Here an example using 7 frames, with average: center, left, right

https://imgsli.com/MjQ4ODEx

The situation get worse if the number of frames is increased.

https://imgsli.com/MjQ4ODEy

I'm trying to write my own average filter, but it is seem that is not possible to access past frames using Vapoursynth

Here my code

def clip_color_stabilizer(clip: vs.VideoNode = None, nframes: int = 5, smooth_type: int = 0) -> vs.VideoNode:
    max_frames = max(1, min(nframes, 31))
        def smooth_frame(n, f):
        f_out = f.copy()
        if n < max_frames:
            return f_out
        img_f = list()
        img_f.append(frame_to_image(f))
        for i in range(1, max_frames):        
            img_f.append(frame_to_image(clip.get_frame(n-i)))
        img_m = color_temporal_stabilizer(img_f, max_frames)
        return image_to_frame(img_m, f_out)    
    clip = clip.std.ModifyFrame(clips=[clip], selector=smooth_frame)
    return clip

#-----------------------------------------------------------------------
def color_temporal_stabilizer(img_f: list, nframes: int = 5) -> Image:
   
    img_new = np.copy(np.asarray(img_f[0]))
   
    yuv_new = cv2.cvtColor(img_new, cv2.COLOR_RGB2YUV)
   
    weight: float = 1.0/nframes

    yuv_m = np.multiply(yuv_new, weight).clip(0, 255).astype(int)
   
    for i in range (1, nframes):
        yuv_i = cv2.cvtColor(np.asarray(img_f[i]), cv2.COLOR_RGB2YUV)
        yuv_m += np.multiply(yuv_i, weight).clip(0, 255).astype(int) 
   
    yuv_new[:, :, 1] = yuv_m[:, :, 1]
    yuv_new[:, :, 2] = yuv_m[:, :, 2]
           
    return Image.fromarray(cv2.cvtColor(yuv_new, cv2.COLOR_YUV2RGB))

The problem is in the call: frame_to_image(clip.get_frame(n-i)) 
When nframes>1 Vapoursynth freeze.

Do you have any idea on how to access past frames from Vapoursynth ?

Thanks,
Dan