My DVD movie has sound, but the extras and menus do not

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further information: DirectShow Playback Guide

This is often caused by using old versions of AC3filter for DVD audio decoding support. The easiest solution is to uninstall AC3filter and use FFDSHOW to handle DVD audio decoding instead, though you must be sure to configure FFDSHOW to handle Dolby Digital decoding (AC3) or you will have problems with no sound at all on DVD playback. Follow the instructions here for further assistance: Dolby AC3

The reason for this is that AC3Filter handles AC3 and DTS audio decoding. The DVD you are using HAS AC3 and/or DTS audio (probably AC3) for surround-sound support. However, like many DVDs, they didn't encode all of the audio to AC3 on the disc, but only encoded the "main movie" file to AC3. All of the menu and extras audio is probably all just 2-channel PCM audio (essentially WAV audio).

The problem is that old (but common) versions AC3filter can't decode PCM audio. It is getting loaded when you start the DVD because the DVD supports AC3, but only for some of the media. AC3filter doesn't know what to do with the PCM audio and just ignores it. Unless you are using AC3filter for some really fancy stuff, it is easier to just get rid of it and use FFDSHOW instead. FFDSHOW is just as capable in almost every way, and far less troublesome.

To remove AC3filter from your system:

  1. Go to Start --> Control Panel
  2. Open the Add/Remove Programs Control Panel
  3. Select AC3filter from the list and choose Remove.
  4. When the removal is complete, reboot the computer.
  5. If needed, install FFDSHOW to handle AC3, DTS, and MPEG-2 audio decoding support. Please refer to the DirectShow Playback Guide for assistance on where to obtain this important filter.

Other Potential Causes

If you're using the Nvidia audio filter from the PureVideo codecs and you adjust the lip-sync delay to more than some amount (possibly 30 ms) it will quit outputting audio for non-AC3 sources. This may only happen if you're using SPDIF output, as it has not been tested extensively.