完美解决 Nextcloud不显示视频缩略图的问题

Nextcloud上传视频文件默认是不生成缩略图的，只能通过一个个点击查看很不方便。解决办法如下；

1，安装ffmpeg和ghostscript

wget http://download1.rpmfusion.org/free/el/rpmfusion-free-release-7.noarch.rpm        #Centos7系统执行 这条命令

wget http://download1.rpmfusion.org/free/el/rpmfusion-free-release-7.noarch.rpm        #Centos6 系统执行这条命令 

rpm -ivh rpmfusion-free-release*.rpm    
  
yum install ffmpeg ffmpeg-devel  

yum install ghostscript  

2，修改config.php

   'default_phone_region' => 'CN',
   'enabledPreviewProviders' => array (  
    0 => 'OC\\Preview\\PNG',  
    1 => 'OC\\Preview\\JPEG',  
    2 => 'OC\\Preview\\GIF',  
    3 => 'OC\\Preview\\HEIC',  
    4 => 'OC\\Preview\\BMP',  
    5 => 'OC\\Preview\\XBitmap',  
    6 => 'OC\\Preview\\MP3',  
    7 => 'OC\\Preview\\TXT',  
    8 => 'OC\\Preview\\MarkDown',  
    9 => 'OC\\Preview\\Movie',  
    10 => 'OC\\Preview\\MP4'  
    ),

3，打开PHP7配置面板，启用exec和system函数

4，刷新一下，视频缩略图出现了！