The weird thing is it works just fine in Windows Terminal. Does CMD reserve commas for something? I really need to use CMD in this case, Since Auotohotkey seems to only speak to CMD.
You'd normally need the full path to dopusrt.exe, since it's not in the default path.
You may also need to give a full path for the output file. Relying on the "documents" folder being under the current dir may not work if AHK is running things with a different current dir.
That probably would've tried to output it to a documents folder under your Opus folder, which presumably doesn't exist (and would normally require admin rights).