the app i used to stream/download from my SMB share is FileExplorer. and I'm certain the DTS movies i tried worked fine on it, while getting the error in Infuse. I'm not sure if it does some type of transcoding or anything before playing? I'll give it another try tonight just to make sure.
EDIT: Yep just tried two files that wouldn't play audio in Infuse, worked fine in FileExplorer.
There's lots of opensource software out there to decode DTS, but to do so legally, you need a license. Barely anybody bothers to get a license (DTS Inc. is notoriously difficult to get a license from), so most apps that support DTS are illegal. FileExplorer doesn't mention DTS support anywhere on their website or AppStore description, nor do they display any DTS logos, so it's likely illegal. I suspect DTS Inc. hasn't called them out on it because they don't advertise the fact they support it.
EDIT: I should clarify that this may not even be intentional on FileExplorer’s part. They may handle all audio by just dumping it into a third-party decoder library, which happens to support DTS. They may not even realize they support DTS or that they need a license to distribute their app if it does so.