Denon 4308 and 1080p Apple TV3 problem - sound but no video.

I need help diagnosing a problem getting 1080p video from an Apple TV3 through my Denon to my Panasonic VT50 plasma. My 720p Apple TV2 works just fine, but my 1080p Apple TV3 only passes through sound not video on the same connection. I've tested the Apple TV3 on a different 720p television and it works, at 720p at least. I also am able to get 1080p video from my Directv receiver and it plays fine through my Denon on my TV.

Here are what I think the possible issues are:

1. HDMI cable from Apple TV to Denon for some reason works at 720p but not 1080p.

2. I have an encoding/decoding setting on my Denon receiver that's different for my Apple TV than my Directv receiver (I've looked and can't find any - basically have all encode/decode set to auto.)

3. My Apple TV outputs 720p okay but has a problem outputting 1080p.


Any suggestions as to what's the more likely culprit among these or if there's something else I should be considering?

Thanks very much for the responses. That helped me figure out how to test and I stumbled across a solution.

I unplugged the HDMI out from my receiver and plugged it into my ATV3, which gave me a direct input into the TV. It worked fine and I verified the output was 1080p/60hz. The weird part is then I plugged it back into the original cable running through my Denon, and it still worked and showed 1080p/60hz!

My guess is that there's some initial handshake it needs to make with the TV that it is not getting through the Denon, and that once that's established it works fine.

So the solution in my case was to plug it directly into the TV and let it boot up prior to plugging it into the receiver.