As the computer and communication technology evolve remarkably, the multimedia data can be handled by the computer. And in the aspect of the communication, new communication protocols for multimedia data transmission have been studied. In the multimedia communication, it is required to transmit altogether various kinds of traffic such as computer data, speech and video signals. As the one result of international activity, MPEG1 system format has been standardized for multimedia information transmission.
In this work, the system format of MPEG1 is used for the transmission of speech and image data. As the source of speech signal, telephone handset is used. To facilitate the voice communication, the interface board with telephone handset is developed onto PC, and it is called TIC. For video signal, only packet video transmission system has been implemented : the video processing system for encoding and decoding of video source signal is beyond the scope of this work.
Voice and video data are packetized respectively, and then they are packed again as one unit. These packs are transmitted through Ethernet network. The packs of MPEG1 bit streams are passed to the Ethernet driver through the packet driver, which is the interface specification between MAC layer of LAN and upper layer protocol.
To control the operation of the system, system status has been introduced. With some input event, the system status changes according to the state transition diagram. The main software consists of five parts : they are state transition handling, telephone interfacing, MPEG1 system format generation, transmitter, and receiver parts. An experiment is carried out satisfactorily except a little of noise and echo.
본 연구에서는 음성 데이타와 영상 데이타를 MPEGl 시스템에서 요구하는 형태로 바꾸어 이써넷 망을 통하여 전송하는 것을 목표로 삼았다. TIC를 구현하여 전화기와 PC를 연결하였고, TIC에서 8msec마다 64 바이트의 음성 데이타가 생성되거나 16msec마다 128 바이트의 음성 데이타가 생성되는 것을 선택할 수 있도록 하였다. 그리고 생성된 음성 데이타를 MPEGl 시스템의 형태로 바꾸어서 전송 및 수신하였고, 수신된 음성 데이타를 TIC를 통하여 상용의 전화기에서 재생되도록 하였다. 곧 개발될 예정인 비디오 코덱에서 나온 영상데이타도 음성과 함께 MPEGl 시스템의 형태로 변형되어 망을 통하여 전송 및 수신될 수 있도록 프로그래밍하였다.
