it sounds like foobar is doing the HDCD decoding on the fly, but the method i am using is only suitable for "batch" processing doing the decoding as the file is ripped. It produces 20-bit output padded to 24-bit in order to capture the additional sound data. One advantage is the replay-gain calculations can be applied to the final output so should be more accurate than when decoded on the fly. The downside of course is the FLAC files will be bigger.
I'll see if i can also implement on-the-fly decoding using a plugin at a later date
butty, i can make the change to show the track is actually HDCD encoded when ripping. But once the file has been decoded to 24-bit there is nothing to indicate that i came from a HDCD (apart from the fact thats its a 24-bit file)