No need to take the file anywhere ..... just down a small tool called Media Info. Instal and then right click on the file opt media info from the windows context menu and you will have all the information about Audio and Video codes used .....
For your issue, if you ask me most of the TVs that play media files off USB only support DD5.1 (AC3). So make sure your file is in the correct audio format, or you TV can support audio other than DD.
Although with a Denon AVR 1311 at your disposal, I'd say getting a small media player that bit streams (All current media players do Bit Stream) is the best bet as then you can let your AVR do all the decoding stuff which make you safe with almost all the A/V formats.
Sam,
I faced the similar problem while checking the demo for Panny U30D plasma tv. I had samples of 1080p videos and I could get see only video and could not hear any audio. The audio was aac encoded.
Is there a way to change the audio to AC3 without loss? I also checked many media players and everything mentioned 1.3HDMI support. Is 1.3 sufficient for 720/1080p video?