How do I know if a 2.0 audio is Dolby ProLogic or not?

[zee944]

Let's say you have 2.0 WAV (of a movie) and you're unsure if it has surround information or not. How can you decide it for sure?

If you decode it as DPL II, will it be obvious? As far as I know, even if you try to decode a plain stereo file there would still be a lot of audio in the surround channels. So then if a company claims they put surround sound onto their VHS, and it's pure stereo, you can't prove it?

Apart from a very subjective checking ("there's a scene in the movie with a helicopter which fly over my head, so if the sound doesn't pan to the rear speakers, then... " etc.), is there a more foolproof method?

Thanks in advance for any valuable input.

[Cornucopia]

No, not really.

Scott