static int ass_detect_change(ASS_Renderer *priv)
{
    ASS_Image *img, *img2;
    int diff;

    if (priv->state.has_clips)
        return 2;

    img = priv->prev_images_root;
    img2 = priv->images_root;
    diff = 0;
    while (img && diff < 2) {
        ASS_Image *next, *next2;
        next = img->next;
        if (img2) {
            int d = ass_image_compare(img, img2);
            if (d > diff)
                diff = d;
            next2 = img2->next;
        } else {
            // previous list is shorter
            diff = 2;
            break;
        }
        img = next;
        img2 = next2;
    }

    // is the previous list longer?
    if (img2)
        diff = 2;

    return diff;
}
Unknown