Visual Media Coding and Transmission

10.4 Performances of Video Transmission in Inter-networked Systems

An MPEG-4 encoder and decoder pair are implemented in real time at the mobile terminals. The connection setup is based on IP/UDP/RTP transport protocols [23]. Video frames are segmented if the video frame size exceeds the specified maximum transfer unit (MTU) size, before being encapsulated into IP packets for transmission. At the receiving end, if IP/UDP/RTP headers are found to be corrupted, data encapsulated within those packets is dropped at the network layer.

The aim of the QoS mapping emulation system is to obtain the optimal bearer configurations for the EGPRS network and the UMTS network. Experiments are carried out to investigate the influences of different bearer configurations on an EDGE-to-UMTS system. First, video transmission is emulated in both EDGE and UMTS systems separately. Second, encoded video is transmitted over the joint EDGE-to-UMTS system. The transmission is emulated over the EDGE system. Then the output data from the EDGE emulator is forwarded to QoS mapping emulator, where the appropriate radio resources are allocated for transmission over the UMTS system. After transmission over the UMTS system, received data is forwarded to the receiving terminal emulator for decoding and display.

10.4.1 Experimental Setup

At first, video transmission emulations are made in both the EGPRS emulator and the UMTS emulator. The MPEG-4 decoder will record the received video data and write to a YUV file. ...