I have OPUS music files in my library.
Symfonium downloads them as oga when I use “Offline cache and download” and turn on Export.
I want to download the files as they are without changes.
Upload description: smish
OPUS file > download (export) to storage > file ends with .oga not with opus as it is originally.
Subsonic
@smish is the hash different or just the filename?
The file is downloaded without changes, the mime type from the server is ogg and Android default extension for that is oga.
This have 0 impact on the file and what can play it, and as said you should use the internal offline features of Symfonium if your need is to play offline.
Why does this happen with Symfonium? I tried running Jellyfish and it downloads music files as they exist in the server.
I would love to continue using Symfonium.
The files are not modified what is your actual use case and need ?
There’s nearly never the need to use the download to downloads folder …
My use case:
Music library is streamed via local Wi-Fi. Albums from various artists are downloaded in bulk and then stored in my library. I discover music inside my local collection (Symfonium is ideal for this).
Favorite songs end up downloaded into my smartphone (or any other device in the network) so they don’t require internet or Wi-Fi to listen to.
So yes just use the proper offline mode of Symfonium to achieve that on a much simpler way.
The reason I download is I move downloaded songs from the library into my music folder which is used by Poweramp.
I don’t understand why the extension changes from opus to oga before downloading.
The question is why use Poweramp over keeping all in Symfonium?
And I just explained your files are ogg container, the format for that on Android is oga, this does not change anything it’s still opus inside and it’s still exactly the same file as the source.
Poweramp plays my offline music files that I can copy, move and backup anywhere. Symfonium is for discovering artists and albums I downloaded in bulk.
Jellyfin downloads files without change in extension. But I prefer Navidrome and Symfonium for music discovery and UI.
At least consider looking into this issue.
Symfonium can do exactly the same as Poweramp + a lot of more things 
Since you still can’t explain why the extension is problematic there’s nothing to look for when using Subsonic.
The two apps - Poweramp and Symfonium - contain two completely different setups. I use each for different purposes.
Anyway. Thank you for your time.
I don’t think this is getting anywhere.
here is more info about ogg/ oga Ogg - Wikipedia
