EE 5359 Multimedia Processing Project Proposal Implementing H.261 Video Codec In H.323 VoIP Stack By Nha Nguyen Student ID: 1000533175 INSTRUCTOR: Prof. Dr. K. R. Rao GTA: Rahul Panchal Spring 2007Implementing of H.261 Video Codec In H.323 Protocol VoIP Stack By Nha Nguyen Abstract: In this project, we will study the H.261 video codec and implement it in the H.323 Protocol Stack. The demo program will be written using open source. We will show how the H.261 works in the H.323 Protocol Stack Voice IP and present the results of video compressing. 1. Introduction H.323, the visual telephone system and equipment for local area network [1], has been developed by the ITU. H.323 is applicable to any packet-switch network which is expected to provide mechanisms such as TCP and UDP. H.323 provides various levels of multimedia communications. These levels include voice, video and data communications over a local area network. Most exciting application of H323 is video telephony over internet. Video applications over an IP network emerged during the last two decades such as video-phone and video-conference. These require a lot of storage capacity. The solution for these applications is data compression before storing or transmitting the data, and decompression when needed. H.261 [2], which is a video coding standard recommended by the International Telecommunication union (ITU), provides a real time video transmission over the integrated services digital network (ISDN). H.261 is a hybrid DPCM/DCT video codec and the coding kernel contains the motion estimation, the motion compensation and the discrete cosine transform modules. In this project, we will study the H.261 video codec and implement it in the H.323 Protocol Stack Voice IP. In section 2, the H.323 protocol is reviewed briefly. We present the H.261 video codec in section 3. We describe the demo program, show how the H.261 works in the H.323 Protocol Stack Voice IP and present the results of video compressing in section 4. The project is concluded in section 5. 2. H.323 Protocol Stack Voice IP H.323, “the visual telephone system and equipment for local area network” [1], which has been developed by the ITU. H.323, provides various levels of multimedia communications. Most exciting application of H323 is video telephony over internet.Figure 1 shows the stack architecture of H.323 [3]. H.26X represents a series of video-encoding standards. In this section, the H.323 protocol will be reviewed. Audio/video application Terminal control and management G.7XX H.26X RTP RTCP H.225.0 Terminal to gatekeeper signaling (RAS) H.225.0 Call setup signaling H.245 Media channel control UDP TCP (IP) Data Link Physical layer Figure1. H.323 protocol stack architecture applied to an IP network. The H.26X represents a series of video-encoding standards. a. H.225: H.225 is a two-part protocol. One part is used for establishment and tear-down of connection between H.323 endpoint. This is known as call signaling or Q931 signaling. The other part of H.225 is known as Registration, Admission and Status (RAS) signaling. This signaling is used between endpoints and gatekeepers and enables a gatekeeper to manage the endpoints within its zone [3]. b. H.245: H.245 is a control protocol used between two or more endpoints. The main purpose of H.245 is to manage the media streams between H.323 session participants [3]. c. RTP (Real-Time Transport Protocol), RTCP ( RTP Control Protocol): They provide the network-transport services that are required for the support of real-time application (such as voice and video) [3]. 3. H.261 video codec H.261 [2] was motivated by the definition and planned deployment of ISDN. It describes the video coding and decoding methods for the moving picture component of audio visual services. H.261 is a hybrid DPCM/DCT video codec. It tries to predict the current picture from the previous one (inter-frame coding) to reduce the picture information to be transmitted (motion compensation). In this section, we will study the structure of H.261: Quantization, Entropy Coding, Motion-Compensated Prediction, Coding Modes, Coding Algorithm for H.261.4. Implementing the H.261 in the H.323 Protocol Stack Voice IP We will implement the H.261 in the H.323 Protocol Stack Voice IP. The demo program [4] will be described and show how the H.261 works in the H.323. Results of video compressing will be presented. 5. Conclusion In this project, we will learn how the H.261 works in H323 Protocol. The demo program will be presented. The new research of H.26X will be continued in the future. Reference: [1] G.A Thoma, “H.323: the multimedia communications standard for local area networks,” IEEE Communications Magazine, Volume 34, Page(s):52 - 56, Dec. 1996. [2] T. Von Roden, “H.261 and MPEG1-a comparison,” Conference Proceedings of the 1996 IEEE Fifteenth Annual International Phoenix Conference on Computers and Communications, 1996, March 1996. [3] D.Collins, “Carrier Grade Voice over IP”, McGraw-Hill, 2001. [4] [Online]. Available:
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