python中加背景音乐如何操作

import pygame# 导入pygame资源包
file=r'E:\Python_Exercise3.mp3'# 音乐的路径
pygame.mixer.init()# 初始化
track = pygame.mixer.music.load(file)# 加载音乐文件
pygame.mixer.music.play()# 开始播放音乐流

import subprocess

inmp4='E:/PycharmProjects/untitled2/hecheng/191030_232_xs.mp4'
inmp3='E:/PycharmProjects/untitled2/hecheng/bg.mp3'
inmp32='E:/PycharmProjects/untitled2/hecheng/bg2.mp3'
outmp3='E:/PycharmProjects/untitled2/hecheng/bg_out.mp3'
outmp4='E:/PycharmProjects/untitled2/hecheng/191030_232_xs_bg.mp4'


cmd='ffmpeg -y -i '+ inmp4 +' -i '+ inmp3 +' -filter_complex \
"[0:a]volume=10dB[a0]; \
[1:a]volume=-10dB[a1]; \
[a0][a1]amix=inputs=2[a]" \
-map 0:v -map "[a]" -c:v copy -c:a aac -shortest '+ outmp4

p = subprocess.call(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

# 查看音轨信息
print('*'*80)
cmd='ffmpeg -i '+ outmp3 +' -filter_complex volumedetect -c:v copy -f null /dev/null'
P = subprocess.call(cmd)