H323网路电话音讯监控.ppt

H.323網路電話音訊監控與錄製系統之研製The Design and Implementation of Audio Monitoring and Recording System for H.323-based Internet Phone Speaker : 黃威穎 Advisor : 柯開維 教授 Data : 2008 07/25 Outline Introduction Background Audio Recover System Framework Compare with Wireshark Conclusion Demo Introduction VoIP has already been the killer application. Requirement of the audio recording system. VoIP protocol H.323 SIP (Session Initiation Protocol) Transport protocol RTP RTCP Background H.323 H.323 Related Software H.323 Related Protocol WinPcap How to Build WAVE File H.323 Framework The Flowchart of H.323 Call Q.931/H.225 Q.931/H.225 call signaling is used to establish a H.323 call. Q.931 Header Structure RTP Header Structure P : Padding Ex : Extension CSRC : contributing source identifiers count M : Mark WinPcap An architecture for packet capture and network analysis for the Win32 platforms. How to Build WAVE File WAVE file format is a subset of RIFF (Resource Interchange File Format) specification. WAVE file format ByteRate = SampleRate * NumChannels * BitsPerSample / 8 BlockAlign = NumChannels * BitsPerSample / 8 Audio Recover Silence Suppression Synchronization Problem Silence Suppression Handle 355920 - 355680 = 240 ((357120 – 355920) / 240) - 1 = 4 Synchronization Problem Handle System Framework System Environment of Network System Structure The Flow of Packet Handle The Interface between RecDrv_h323.dll and RecApp.exe System Environment of Network System Structure The Flow of Packet Handle Compare with Wireshark Compare with Wireshark (cont.) * * * * * * H.323 H.323 is a multimedia conferencing protocol, which includes audio, video, and data conferencing over packet-switched networks. Element of H.323 system Terminals Gatekeeper Multipoint Control Units (MCU) Gateway * * * H.323 Related Software OpenH323 An open source library for the development of applications using the H.323 protocol. GNU Gatekeeper (GUNGK) An open source project that implements an H.323 gatekeeper. Im