The AV inputs are: yellow: composite video, red & white: stereo audio, and the S-video is video only (use either the yellow or the S-video, not both).

You don't have Dolby Digital (AC-3) because you don't have a digital audio connection, aka S/PDIF (Sony/Philips Digital Interconnect Format).

There should be an RCA jack (typically orange or black) and/or an optical connector (roughly rectangular opening, may have a stubby cover plugged into it).

Most DVD players have one (or two) set(s) of yellow, red, and white jacks, a set of red, green, and blue jacks (component video), and one RCA and/or optical digital audio output.

You must use the digital connection for Dolby Digital and DTS. The best you can get from stereo audio outputs is Dolby ProLogic

Larry
www.fineelectricco.com.