import requests

def get_cid_from_bv(bv_id):
    # 视频详情 API 地址
    video_url = f'https://api.bilibili.com/x/web-interface/view?bvid={bv_id}'
    
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36'
    }
    
    # 发送请求
    response = requests.get(video_url, headers=headers)
    response.raise_for_status()
    data = response.json()
    
    # 提取 cid
    if data.get('code') == 0:
        cid = data.get('data', {}).get('cid')
        return cid
    else:
        return None

# 使用示例
bv_id = 'BV1m7411e71N'  # 替换为你的视频 BV 号
cid = get_cid_from_bv(bv_id)
print(f'CID: {cid}')