pygame没报错却黑屏，音乐都有

曲速飞跃

import pygame
import sys
import traceback
from pygame.locals import *
from random import *

# 球类继承自Spirte类
class Ball(pygame.sprite.Sprite):
    def __init__(self, grayball_image,  position, speed, bg_size):
        # 初始化动画精灵
        pygame.sprite.Sprite.__init__(self)

        self.grayball_image = pygame.image.load(grayball_image).convert_alpha()
        self.rect = self.grayball_image.get_rect()
        # 将小球放在指定位置
        self.rect.left, self.rect.top = position
        self.side = [choice([-1, 1]), choice([-1, 1])]
        self.speed = speed
        self.collide = False
        self.control = False
        self.width, self.height = bg_size[0], bg_size[1]
        self.radius = self.rect.width / 2

    def move(self):
        if self.control:
            self.rect = self.rect.move(self.speed)
        else:
            self.rect = self.rect.move((self.side[0] * self.speed[0], \
                                        self.side[1] * self.speed[1]))

        # 如果小球的左侧出了边界，那么将小球左侧的位置改为右侧的边界
        # 这样便实现了从左边进入，右边出来的效果
        if self.rect.right <= 0:
            self.rect.left = self.width

        elif self.rect.left >= self.width:
            self.rect.right = 0

        elif self.rect.bottom <= 0:
            self.rect.top = self.height

        elif self.rect.top >= self.height:
            self.rect.bottom = 0
        
def main():
    pygame.init()

    grayball_image = "UFO.jpg"
    bg_image = "background.jpg"

    running = True

    # 添加背景音乐
    pygame.mixer.music.load("music.ogg")
    pygame.mixer.music.play()

    # 添加音效
    loser_sound = pygame.mixer.Sound("fail.ogg")
    laugh_sound = pygame.mixer.Sound("laugh.ogg")
    winner_sound = pygame.mixer.Sound("win.ogg")

    # 根据背景图片指定游戏界面尺寸
    bg_size = width, height = 1200,800
    screen = pygame.display.set_mode(bg_size)
    pygame.display.set_caption("Play the ball - FishC Demo")

    background = pygame.image.load(bg_image).convert_alpha()

    # 用来存放小球对象的列表
    balls = []
    group = pygame.sprite.Group()

    # 创建 5 个小球
    for i in range(5):
        # 位置随机，速度随机
        position = randint(0, width-100), randint(0, height-100)
        speed = [randint(1, 10), randint(1, 10)]
        ball = Ball(grayball_image, position, speed, bg_size)
        # 检测新诞生的球是否会卡住其他球
        while pygame.sprite.spritecollide(ball, group, False, pygame.sprite.collide_circle):
            ball.rect.left, ball.rect.top = randint(0, width-100), randint(0, height-100)
        balls.append(ball)
        group.add(ball)


if __name__ == "__main__":
    try:
        main()
    except SystemExit:
        pass
    except:
        traceback.print_exc()
        pygame.quit()
        input()