AC3Filter config utility
You may configure AC3Filter with AC3Filter config tool (Start -> All programs -> AC3Filter -> AC3Filter config). When you configure the filter in this way, changes you made do not affect the current playback. You have to restart the media player for the changes to take effect. Also, all 'live' controls (level meters, spectrum display, etc) will not show any activity.
 Tray icon
It is possible configure the currently playing audio with tray icon. If you don't see the tray icon, it may be disabled or the player you use do not utilize AC3Filter. You can enable the tray icon at AC3Filter:System page.
Click on the tray icon with the left mouse button to call AC3Filter config dialog. It will show you the current audio activity and changes you made take effect immediately (several seconds delay is possible).
 Command line
At last, you may control AC3Filter from the command line with help of ac3config utility. You can use the following command lines:
ac3config /preset MyPreset /q
Load 'MyPreset' preset and exit (do not show the dialog). Note, that this command does not affect current playback, it just changes the default preset. Only applications started later are affected.
ac3config /remote "Enable SPDIF" /q
You can specify such command line at your infrared control application to control the current playback. Note that default preset is not affected in this case. Applications started later will use an old default preset.