启动open-webui的时候报错Couldn't find ffmpeg or avconv
具体内容：
INFO [open_webui.env] Embedding model set: sentence-transformers/all-MiniLM-L6-v2
E:\py311\Lib\site-packages\pydub\utils.py:170: RuntimeWarning: Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work
warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)
WARNI [langchain_community.utils.user_agent] USER_AGENT environment variable not set, consider setting it to identify your requests.
尝试安装ffmpeg方法1
尝试使用python pip安装，使用命令：
pip install ffmpeg安装完成后，问题没有解决，启动open-webui还是报错。
尝试安装ffmpeg方法2
直接安装windows下的二进制执行版。
进入官网：FFmpeg
下载windows版本软件
Download FFmpeg
查看发布版本：
Releases · BtbN/FFmpeg-Builds · GitHub
下载ffmpeg-master-latest-win64-gpl.zip 这个文件
解压到目标目录，比如E:\ai\ffmpeg-master-latest-win64-gpl 目录
设置windows的环境变量，在PATH里加入ffmpeg的执行文件所在的目录：
E:\ai\ffmpeg-master-latest-win64-gpl\bin
使用set看看环境变量，发现已经加到最后了：
Path=E:\py311\Scripts;E:\Program Files\cuda12\bin;E:\Program Files\cuda12\libnvvp;C:\Program Files\VanDyke Software\Clients\;E:\Program Files\cuda\bin;E:\Program Files\cuda\libnvvp;C:\Program Files (x86)\Common Files\Intel\Shared Libraries\redist\intel64\compiler;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files\dotnet\;C:\Program Files\Microsoft SQL Server\150\Tools\Binn\;C:\Program Files\Microsoft SQL Server\Client SDK\ODBC\170\Tools\Binn\;C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;e:\Program Files\Git\cmd;C:\Program Files\NVIDIA Corporation\Nsight Compute 2024.1.1\;E:\Program Files\PuTTY\;C:\Program Files\Docker\Docker\resources\bin;E:\Program Files\anaconda;E:\Program Files\anaconda\Library\mingw-w64\bin;E:\Program Files\anaconda\Library\usr\bin;E:\Program Files\anaconda\Library\bin;E:\Program Files\anaconda\Scripts;C:\Users\Admin\AppData\Local\Microsoft\WindowsApps;C:\Users\Admin\.dotnet\tools;C:\Users\Admin\AppData\Local\Programs\Ollama;e:\Programs\Microsoft VS Code\bin;C:\Users\Admin\AppData\Local\Muse Hub\lib;e:\Program Files\Huawei\DevEco Studio\bin;;E:\ai\ffmpeg-master-latest-win64-gpl\bin;
