Figure 17. Protocol stack for a digital media player
Digital Media Controllers
Users who have DMC devices can browse content from any Windows PC and play that content in any other Windows PC or device that is connected to the home network and that implements the DMR role. Windows 7 implements a DMC, which is necessary to the Play To feature that was described earlier. After a DMR is selected for playback, the media controller is started to remotely control the playback experience. A user can have multiple media controllers open at any time and controlling playback to an equal number of DMRs in the network. Figure 18 shows this media controller, from which the following playback controls are available: Play, Pause, Stop, Mute, Volume, Next Item, Previous Item, Seek Forward, and Seek Backward.
Figure 18. Windows 7 DMC controlling playback when the Play To feature is used in Windows Media Player and Windows Explorer
For example, a user can have network media devices that implement the DMR role in every room of the home. The family room DMR is an HDTV that supports playback of video, music, and pictures, and the bedroom DMR is a digital picture frame. The DMR for the kitchen and den is a network radio that supports only audio. From a Windows 7 PC, a user can concurrently send pictures to the bedroom digital picture frame, video to the family room HDTV, jazz music to the kitchen, and rock music to the den.
Figure 19 shows the protocol layers in a digital media controller. DMC devices support Wi-Fi or Ethernet for connectivity. DMC devices implement TCP/IP, UDP/IP, and HTTP. They implement the UPnP control point functionality that includes a media server control point and a media renderer control point.
Figure 19. Protocol stack for a DMC
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