I have a hard drive with MP4/AC3 files on it. Also some AAC files. I plugged it into the USB port of my DMP-BDT220 player. It recognizes the files and plays the MP4's with the AAC audio files. However, the files with AC3 audio play with video but no audio. Is this because it won't read or process AC3 files on the USB drive or is there some settings somewhere that I need to change. It's connected with HDMI to an Onkyo TX-NR905. The AC3 files were created by ripping DVD's using Handbrake with AC3 Passthrough selected. The files are ok because I can import them into my iTunes library and play them through my Apple TV with full Dolby surround sound.