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MPEG-4 video transmission for ambulatory application Mamoru Hashimoto NEC Corporation Satellite Ambulance Hospital Multi Channel Patient Video Multiplexing Live Videos Control Data Transport Data Camera Cameras Electro Cardiogram Seamless Multi Modal Multi Screens Control
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MPEG-4 video transmissionfor ambulatory application Mamoru Hashimoto NEC Corporation
Satellite Ambulance Hospital Multi Channel Patient Video Multiplexing Live Videos Control Data Transport Data Camera Cameras Electro Cardiogram Seamless Multi Modal Multi Screens Control Medical Equipments Emergency medical video transmission Transmission of video from the moving ambulance to the hospital Workshop on Standardization in E-health
Assumption for system configuration Ambulance May be plural Video camera Transmitter Computer NTSC (can be PAL) 100BASE-TX Wireless communications Hospital May be plural Receiver Computer projector 100BASE-TX Workshop on Standardization in E-health
Processing in ambulance side Digitizing of video signal with video capture cards Capturing Transforming of digitized video signal into compressed bitstream Encoding Dividing the bitstream into packets with bitstream format preserved Packetizing Adding RTP header to packets and transmitting with UDP/IP Transmitting Workshop on Standardization in E-health
Processing in hospital side Receiving packets sent in UDP/IP Receiving Removing RTP header from packetsand reconstructing bitstream for one frame Depacketizing Decoding bitstream and producing image data for one frame Decoding Displaying image data for one frame Displaying Workshop on Standardization in E-health
Encoding / decoding process • Using self-made software codec conforming to MPEG-4 Visual simple profile • The software codec can process the video stream of QVGA resolution and 15 fps (including communication processing) Workshop on Standardization in E-health
Transmitting / receiving process with RTP protocol • Adding RTP header and transmitting / receiving the packets in UDP/IP • Detecting disorder, packet loss and fluctuation of arrival with sequence number and timestamp • Dividing MPEG-4 bitstream into packets in accordance with RFC3016 • Not using RTSP Workshop on Standardization in E-health
An algorithm for concealing packet loss Using the spatial similarity in the picture (outside of the standards) Odd line picture Even line picture Before transformation After transformation Workshop on Standardization in E-health
About measures for loss of RTP packets • Concealment process is CPU intensive • With forward error correction codes (even with the simplest parity codes), packet loss can be recovered • For RTP packets, RFC2733 can be used; but it is restricted to continuous 24 packets • Underlying protocols is responsible? Workshop on Standardization in E-health
Future works • To conduct the video transmission experiment with experimental vehicles • To construct effective and efficient error correcting codes • To determine the necessary resolution and bitrate for medical image • To find more appropriate underlying protocols (UDP/IP is not necessary) Workshop on Standardization in E-health