fatal error C1083: Cannot open include file: 'libavcodec/avcodec.h': No such file or directory

[ruggedsource]

when I try to install the package:

python setup.py install
C:\Users\2600\subsync\gizmo\media\decoder.h(9): fatal error C1083: Cannot open include file: 'libavcodec/avcodec.h': No such file or directory
error: command 'C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.41.34120\bin\HostX86\x64\cl.exe' failed with exit code 2

I saw people suggesting I should reinstall ffmpeg for the includes but tells me everything is working:

pip install ffmpeg
Requirement already satisfied: ffmpeg in c:\users\2600\venv\lib\site-packages (1.4)

Do I have to install the package in a different directory? So that it can locate the includes. Or am I mis understanding the error?