# Media flows when using the Video Transcoder

An optional video transcoder controls real-time media adaptation between two IP devices. The Video Transcoder (available as a separate product from NMS) enables video applications to control transcoding channels in the video transcoder platform.

The following illustration shows the media flow in a video mail system for a scenario in which H.263 baseline video is the negotiated format in the 3G-324M connection:

All MPEG-4 video content played to the terminal must go through the Video Transcoder so that it can be processed by the terminal. The Video Messaging Server Interface can transfer H.263 mail messages directly to the 3G-324M Interface.

The application is responsible for correctly configuring RTP endpoint on the server so that the server sends RTP packets from the Video Messaging Server Interface by one of the following messages:

- Through the video transcoder platform, which then relays the packets to the 3G-324M Interface

- Directly to the 3G-324M Interface (internally on the CG board if a single board is used).

For recording operations, H.263 video is transferred via RTP from the 3G-324M Interface to the Video Messaging Server Interface where it is stored in 3GP format.

For more information, refer to the Video Transcoder Developer's Reference Manual.