As above I have located the ffmpeg file in RoonOnNAS/bin not in a random directory. Are you suggesting it should be a different location? The text file(Info about this folder.txt) in this folder reads:
‘You can provide your own version of ffmpeg in this folder.
ffmpeg is a software component of your diskstation. However it might not include all required audio codecs. Therefore Roon might not be able to play some media files.
If you provide your own version of ffmpeg in this folder, you’ll need to restart Roon Server afterwards in the Synology package center.’
So I think the file is in the right place but refreshing RoonServer I still cannot stream AAC for example.