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網路視訊會議系統的設計與經驗 莊 志 洋 民友科技股份有限公司.

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Presentation on theme: "網路視訊會議系統的設計與經驗 莊 志 洋 民友科技股份有限公司."— Presentation transcript:

1 網路視訊會議系統的設計與經驗 莊 志 洋 民友科技股份有限公司

2 Agenda H.323 and related protocols Ready for right products
Design Considerations Experiences and Suggestions

3 What is H.323? A multimedia communication protocol suite
Includes voice, video, and data conferencing For use over packet-switched networks * H.323 is “ITU-T Recommendation H.323: Packet-based multimedia communications systems”

4 Elements of an H.323 System Terminals Multipoint Control Units (MCUs)
Gateways Gatekeeper Border Elements

5 H.323 Network Elements PSN CSN H.323 Terminal H.323 MCU
H.323 Gatekeeper H.323 Gateway H.323 Terminal H.323 Terminal PSN CSN GSTN GQOS LAN N-ISDN B-ISDN V.70 Terminal H.324 Terminal Speech Terminal H.322 Terminal H.320 Terminal H.321 Terminal

6 Terminals                                                               

7 MCUs For managing multipoint conferences Contains
Multipoint Controller (MC) - manages the call signaling Multipoint Processors (MPs) - handle media mixing, switching, or other media processing

8 Gateways Interface H.323 to other networks, Composed of MGC handles
including the PSTN, H.320 systems, other H.323 networks (proxy), etc. Composed of a “Media Gateway Controller” (MGC) a “Media Gateway” (MG) MGC handles call signaling , non-media-related functions MG handles the media

9 Gatekeeper Admission control Address resolution
e.g.,Phone number to IP address

10 Border Elements Exchange addressing information and participate in call authorization between administrative domains Often co-located with a Gatekeeper,

11 Packet-switched Network
An H.323 Stack H.323 Application RAS H.245 RTP / RTCP H.225.0 Call Signaling Packet-switched Network

12 H.323 basic protocols Gatekeeper Annex G Gatekeeper Q.931/H.245 RAS
Signalling (Q.931) Endpoint Endpoint H.245 RTP/RTCP Gatekeeper Routed Signaling Direct Routed Signaling Source: Lior Moscovici

13 H.323 related standards RTP/RTCP : Streaming T.120 - Data conferencing
Audio Codecs: G.711, G.722, G.723.1, G.728, G.729, GSM Video Codecs: H.261, H.263, H.264

14 Past to Present Or was it? H.323 v.1 was published in 1996
was designed for LANs Or was it? Version 1 (1996) was designed with the Local Area Network in mind. H.323 has its roots in the video conferencing area, borrowing much of the multimedia conferencing aspects from other H.32x-series Recommendations, such as H H.323 was intended to allow people on a LAN to conduct an audio, video, and data conference (with the help of T.120). Or was it? Local Area Network

15 Past to Present But, it was used in WANs, large private VoIP networks, and the Internet It worked very well Early comers to the H.323 market, such as VocalTec, recognized H.323’s potential for Internet Telephony.

16 Past to Present H.323 proved that
RTP is able to carry real-time audio and video over IP networks that span the globe Indeed, H.323 was much more than a LAN protocol RTP, as probably everyone in the IP Telephony space knows, is the same media transport protocol used by both H.323 and SIP devices. The early designers of H.323 recognized the potential of embracing, not only the packet network, but also the IETF protocols have helped make the Internet what is is today. For this and other reasons, H.323 is well-suited for multimedia conferencing over IP networks, including the Internet.

17 Past To Present Recognizing the fact that H.323 was much more than a LAN protocol, the name was changed in H.323 Version 2 (1998) Enhancements were made, including: Security Performance Supplementary Services Scalability The name of H.323 was changed to “Packet-based multimedia communications systems”.

18 Strength in Numbers Partial Listing Accord Networks Aethra
AG Communications Agilent Anatel Aspect Atlantic Avaya Axent Brooktrout Technology CUseeMe Callserve Catapult CheckPoint China Netcom China Telecom China Unicom Cirilium Cisco Systems Clarent Comverse Data Connection Delta Information Systems Dialogic Dialpad E-Tech Canada Ltd. Elemedia Equivalence e-tel eZenia! FVC Genuity HearMe Huawei Hughes Software Systems iBasis IBM Inalp Networks Inari Inc. Innovaphone Intel ISPhone ITXC Ji-Tong Communications Komodo Technology Lotus Lucent Macchina Madge Networks Microsoft Motorola MultiTech Systems Natural MicroSystems NetSpeak WebPhone Netergy Networks Network Associates NexTone Nuera Communications Nx Networks OKI Packetizer Pagoo PictureTel Polycom RADCom RADVision Ridgeway Systems Siemens Smith Micro Sorenson Vision Swyx Symbol Technologies Telxon TINY Teles Trillium Unylogix VCON VegaStream VIVE Technologies VTEL VocalTec WowRing Zydacron Partial Listing

19 The Market Today Today, the biggest market for H.323 applications is Voice over IP. Why? Lack of right video terminals to address: Low bit-rate Internet connections make video and data intensive applications less appealing It’s a young industry– and with all such industries, it takes time to mature good products Companies can provide VoIP services today at a low cost and provide new competition to the incumbent carriers

20 Video Communication Era
Future, expect to see video and data communication to become more pervasive Broadband connectivity is making it possible Video and data are logically the next services customers expect to find in conference rooms, at home and on their computer screens

21 Why current H.323 products is not good?
Unstable Video Quality Good over dedicated lines or in demo room Deteriorates significantly over Internet Difficult to install Not easy to use Too expensive Business model

22 Design Considerations

23 Networking environment
Backbone band-width oversupply Last-mile bandwidth getting better > 384K bps at < NT$2,000/m xDSL, ADSL, VDSL Cable WLAN / WiMax 3G

24 IP Network Issues Lack of IP addresses Use of NAT Firewall
Dynamic IP Virtual IP Use of NAT Adds difficulties to address resolution Firewall Blocks media packets Make plug & play less possible

25 Codec Issues Standard algorithms Implementations: Hardware vs Software
Computation speed Bit rate vs picture quality Hardware vs Software DSP No longer a dominating issue

26 Performance bottlenecks
Not at computation unit (DSP or CPU) Systems: Buffers Internal bus Memory speed Graphics display

27 Right prices for right users
Corporate users Large conference room ~NT$1.0M Small conference room NT$50k – NT$100k Desk top with PC ~NT$3K Soho users < NT$50k Home users < NT$10k Personal users < NT$6k

28 Common Requirements 接近電視的影音品質 維護容易又穩定 容易安裝,網路設定比PC簡單 不必學就會用 不必守在機器旁
慣用的撥接方式 (phone, PC, PDA, etc) 不必守在機器旁 各式來電通知機制 (ring, , mobile, etc)

29 Common requirements 固定IP、浮動IP、虛擬IP的用戶都可接通 網路擁塞 – Lack of QoS in Net
智慧型影音流量調控 Use better end-point QoS 對話安全 影音加密

30 貼近企業文化的設計 讓傳真變彩色 PC上的資料可隨時取得 反映手寫習慣的電子白板 輕鬆地作現場演示 遠距簡報洽商業務 異地同仁如處同地辦公
連接網路的芳鄰 反映手寫習慣的電子白板 輕鬆地作現場演示 遠端PC程式執行能力 遠距簡報洽商業務 異地同仁如處同地辦公 遠距同步操作PC

31 貼近企業文化的設計 多點同步會議功能 各個角度都看得到 保留珍貴的會議時況 內建MCU 遙控攝影機: 轉向,聚焦 多攝影機設計
多頻道數位錄影 – 影音圖文同步錄影

32 Suggested HW architecture
P4 for corporate and soho users SOC = DSP + RSIC for home and personal/mobile users Camera VGA resolution at 30 fps High-end webcam is good enough Display VGA monitor vs TV Speaker and Microphone Headphone is uncomfortable Conference phone is a good choice Full duplex and echo cancellation

33 Suggested SW Architecture
Embedded Linux Spport P4 & RISC platforms Complete TCP/IP stack Embedded Windows and GUI Small but rich Interoperable vs compatible Standard H.323 Optimized implementation

34 Data Conference Work with PC / MS Windows RDP Network Neighbor – Samba
Graphical terminal Network Neighbor – Samba Network file system Multi-point screen sync T.120 H.323 whiteboard standard

35 More than Data Conference
Distance Collaboration Run programs Co-design Life demonstrations Scratch paper – notepad etc

36 Results 嵌入式設計、多點視訊會議、影音加密、代碼撥號、來電通知、遠端影音調控、PC網路芳鄰、遠距簡報、電子白板與即時圖文通訊、線上文字交談、彩色傳真、Fax over IP Gateway、影音留言、會議錄影 More than a H.323 system At an affordable price



39 Product Varieties Stand-alone Embedded in LCD monitor/HDTV
Embedded in xDSL Built-in PDA/PPC/PMP/DSC Must have in mobile phone

40 Remarks Internet is ready for video communication
H.323 is a valid protocol, SIP simplifies call setup Multimedia communication with Voice, video, text, graphics, 3D, Design issues are on the system integration, HW and SW Embedded in various products

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