Implementation Notes

To add an audio or video format for use with NetMeeting, first obtain the appropriate interface by calling the COM CoCreateInstance function, providing the desired interface (IInstallAudioCodecs or IInstallVideoCodecs). Then call the add method (AddACMFormat or AddVCMFormat) on this interface to add a format, or call the remove method (RemoveACMFormat or RemoveVCMFormat) to remove a format. Use the IInstallVideoCodecs::EnumFormats (or IInstallAudioCodecs::EnumFormats) method to enumerate the list of formats known to NetMeeting, or IInstallVideoCodecs::ReorderFormats (or IInstallAudioCodecs::ReorderFormats) to make NetMeeting use these formats in a different priority order (see the comment in the IInstallAudioCodecs::ReorderFormats or the IInstallVideoCodecs::ReorderFormats description).

When a vendor uses the Installable Codecs API to add a codec format for use with NetMeeting, the information about this format is stored in the registry. Whenever NetMeeting is upgraded, the NetMeeting setup removes all registry entries associated with the previous version of NetMeeting, including information about additional audio or video codec formats. This registry clearing is required to avoid incompatibility problems between different versions of NetMeeting. As a result, a user will have to reinstall any custom audio or video codec format after upgrading NetMeeting.