|Microsoft DirectX 9.0|
There are three sources of DVD region information that work together to determine the region for DVD playback on a Windows PC.
Most DVD titles are marked for a specific region. Some titles can be played in only one region, some can be played in multiple regions, and others can be played all regions.
There are two types of DVD-ROM drives: RPC Phase 1 and RPC Phase 2 (hereafter referred to as RPC1 and RPC2) drives. RPC1 drives do not have built-in hardware support for region management. For these drives, Windows maintains the region change count information and the region can be changed only once. RPC2 drives maintain the region change count information in hardware and in general the region of such drives can be changed up to 5 times.
Some DVD decoders, hardware or software, are set for a specific region. In general, the user cannot change the decoder's region.