Update – As commentor Nate mentioned, it appears as though the Dolby Digital markings are back on the Apple TV for the appropriate titles. Great news other then the fact that we have to go back through a weeks worth of titles to backtrack what titles really did contain DD 5.1 surround sound. Thanks Apple!

If you’re an audiophile, and have noticed recently that Apple has been offering up less and less titles with Dolby Digital 5.1 surround sound, then you are not alone. First and foremost Dolby Surround is not available with all SD rentals, and Dolby Digital 5.1 surround sound is not available with all HD rentals. Since we track these movies everyday we have a pretty good idea of what titles contain DD 5.1 and what doesn’t and it seems as though Apple has wiped all signs of any titles containing DD 5.1 sound either on the Apple TV listings or iTunes Store. For instance, as in the screen shot above, we know for a fact that Iron Man did contain DD 5.1 when it was released as an HD rental.

Now what does this mean, who knows. If I was a betting man, and knowing Apple’s track record with these kinds of things, I would say it was a glitch in Apple’s system. All though, what if Apple was upgrading the sound quality, or audio tracks in general, of these titles. Time will tell.