Python视频宽高比处理代码：横向正常纵向失效问题求助

我用Python编写的视频宽高比处理代码在横向视频上运行正常，但处理纵向视频时完全失效。先后尝试了两种基于FFmpeg的实现方案，问题仍未解决，具体代码如下：

def apply_aspect_ratio(video_path: str, aspect_ratio: str, output_path: str) -> None:

    target_width, target_height = map(int, aspect_ratio.split(':'))

    width, height = get_video_size(video_path)

    scale_width = width / target_width
    scale_height = height / target_height

    if scale_width > scale_height:
        # 横向填充
        pad = int(((width / target_width * target_height) - height) / 2)
        filter_string = f"pad={width}:{width//target_width*target_height}:(ow-iw)/2:{pad}"
        # filter_string = f"scale={width}:{new_height},pad={width}:{new_height}:{pad_top}:{pad_bottom}"
    else:
        # 纵向填充
        pad = int(((height / target_height * target_width) - width) / 2)
        filter_string = f"pad={height//target_height*target_width}:{height}:(ow-iw)/2:{pad}"

    cmd = [
        'ffmpeg', '-i', video_path, '-vf', filter_string, 
        '-c:v', 'libx264', '-preset', 'fast', output_path
    ]
    subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    print(f"Applied aspect ratio = {aspect_ratio} to {video_path}")

我尝试了这种方案但仍然无效

import subprocess

def apply_aspect_ratio(video_path: str, aspect_ratio: str, output_path: str) -> None:
    # 拆分目标宽高比
    target_width, target_height = map(int, aspect_ratio.split(':'))

    # 获取视频原始尺寸
    width, height = get_video_size(video_path)

    # 计算缩放比例
    scale_width = width / target_width
    scale_height = height / target_height

    # 计算填充参数
    if scale_width > scale_height:
        # 横向填充
        new_height = int(width / target_width * target_height)
        pad_top = (new_height - height) // 2
        pad_bottom = new_height - height - pad_top
        filter_string = f"scale={width}:{new_height},pad={width}:{new_height}:{pad_top}:{pad_bottom}"
    else:
        # 纵向填充
        new_width = int(height / target_height * target_width)
        pad_left = (new_width - width) // 2
        pad_right = new_width - width - pad_left
        filter_string = f"scale={new_width}:{height},pad={new_width}:{height}:{pad_left}:{pad_right}"

    # 构建FFmpeg命令
    cmd = [
        'ffmpeg', '-i', video_path, '-vf', filter_string, 
        '-c:v', 'libx264', '-preset', 'fast', output_path
    ]
    subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    print(f"Applied aspect ratio = {aspect_ratio} to {video_path}")

def get_video_size(video_path: str):
    cmd = [
        'ffprobe', '-v', 'error', '-select_streams', 'v:0',
        '-show_entries', 'stream=width,height', '-of', 'csv=s=x:p=0', video_path
    ]
    result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
    width, height = map(int, result.stdout.strip().split('x'))
    return width, height

内容的提问来源于stack exchange，提问作者Junbutaw Tawbutaw