![Packet Video & Audio Tools on PC’s (A Cookbook) February 7-11, 2000 H.A. “Kipp” Kippenhan, Jr. [kippenhan@fnal.gov]](https://image.slidesharecdn.com/powerpoint4526/85/PowerPoint-1-320.jpg)
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- 1. Packet Video & Audio Tools on PC’s (A Cookbook) February 7-11, 2000 H.A. “Kipp” Kippenhan, Jr. [kippenhan@fnal.gov]
- 2. Outline Classification of systems Packet Tools - Background ITU Standards Applications Audio considerations Video considerations Additional suggestions Summary Questions
- 3. Classification of Systems – Pre H.323
- 4. Classification of Systems – Post H.323
- 5. Packet Tools - Background Genus of the tools was research at Xerox PARC and Lawrence Berkeley Laboratory Tools generally needed to participate sdr (session directory) vic (video conferencing tool) rat (robust audio tool) vat (visual audio tool) wbd (white board) Targeted for IP multicast (interactive use is more demanding) What works well on Unix workstations may work differently (?not so well?) on PC’s
- 6. ITU Standards H.320 umbrella standard Video & audio over public switched telephone network (e.g. - ISDN) H.323 umbrella standard Video & audio over networks with no Quality of Service guarantee (i.e. – TCP/IP) Video encoding H.261 encoding (part of H.320) Discrete cosine transform encoding Maximum of 352x288 pixel resolution Subset of MPEG encoding (optimized for symmetric transmission/reception)
- 7. ITU Standards Video encoding H.263 encoding (part of H.323) Improved motion compensation (a factor of 5) Maximum of 352x288 pixel resolution Provision for 704x576 and 1408x1152 resolution (no products presently available) Audio encoding (H.320 & H.323) G.711 encoding – 3 KHz audio (uses 48, 56 or 64 Kbps of bandwidth) G.722 encoding – 7 KHz audio (uses 48, 56, or 64 Kbps of bandwidth) G.728 encoding – 3KHz audio (uses 16 Kbps of bandwidth)
- 8. ITU Standards Audio encoding (H.323 unique) G.723 – 3 KHz audio (uses 6.4 or 5.3 Kbps of bandwidth) G.729 – 3 KHz audio (uses 8 Kbps of bandwidth) What’s important Only G.711 must be supported (even in H.323 products) G.723 encoding is shipping in commercial products (e.g. – Cisco) H.323 encoding only supports 352x288 pixels (in products shipping today) Voice over IP products are classed as H.323 compliant
- 9. The Applications Audio Tools Provide for the transmission/reception of audio information via packet networks Vat (4.0b2) Provides echo cancellation PC version not full duplex audio No recent development work Rat (v 3.0.35) No echo cancellation Supports full-duplex audio Supported by UCL (MECCANO project)
- 10. The Applications Video tools Provide for the transmission/reception of video information via packet networks Nv Doesn’t support H.261 encoding Supports 640x480 resolution No recent development Vic (2.8ucl-1.0) Support H.261 and H.263 encoding 352x288 (FCIF) resolution (640x480 – nv encoding) Supported by UCL (MECCANO project)
- 11. The Applications Other tools There are a variety of other tools (e.g. – HEPNRC multi-session bridge, VRVS) available for various special needs. They won’t be discussed here Sdr (ver. 2.9) Supports the announcement of or joining of IP multicast sessions on the Mbone If announcing a session, the sdr process must not be stopped (announcement will disappear) Automatically launches other tools (vic, rat, wbd, …) Supported by UCL (MECCANO project)
- 12. The Applications Wbd (ver. 1.0ucl4) A conferencing tool – not a drawing tool Import previously prepared drawings (postscript format) Supports shared text (like ‘chat’) Supported by UCL (MECCANO project)
- 13. Audio Considerations Only important if you want to present (i.e. – source audio) Echo cancellation Not supported by rat For groups, use hardware that supports it (e.g. – Polycom SoundPoint (speaker / microphone) Audio level control Too many level controls to tweak (especially with Windows) On speaker Sound card (software – in systray) Application (slider bar in rat)
- 14. Audio Considerations Karaoke effect Disable feature when using rat or vat PC sound system usable as a Public Address (PA) system Full-duplex problem PC hardware Chipset on motherboard (not full-duplex until recently) Discrete sound card (may not be full-duplex) Driver May not support full-duplex operation Verification Must do a point-to-point connection using rat
- 15. Audio Considerations Windows 2000 now shipping Don’t assume anything Compatibility issues Users must perform tests
- 16. Video Considerations Only important if you want to present (i.e. – source video) Video capture card unnecessary if PC operating system supports USB devices - use a USB camera (e.g - 3Com #3718) Drivers are always a problem (get latest from vendor web site) HEPNRC has had success with the Hauppauge Win-TV (model 401) Windows 2000 now shipping Compatibility issues Users must perform tests
- 17. Additional Suggestions For a single user, get a headset (e.g. – LabTec C-324) Disable ‘suppress silence’ option in audio tool (not doing so produces unacceptable audio performance on PC’s) Adopt push-to-talk model (use mouse to enable microphone) Accept variability of audio level between systems Test your system before the day of an important meeting Currently no bridge between H.323 / H.323 end points and packet tools (e.g. – Polycom to VRVS)
- 18. Summary H.323 (connection based) devices are appearing at HEP research sites There’s still life in your H.320 (ISDN based) codec New codec purchases should support both standards – H.320 & H.323 (e.g. - Polycom Viewstation) MCU’s (e.g. – Accord MGC-100) will support hybrid meetings (mixture of H.320 & H.323 devices) IP firewalls and H.323 devices don’t interoperate well (it takes some tuning)
- 19. Summary Vic (H.263) and rat (G.728) support necessary standards – why don’t H.323 systems interoperate with VRVS? No way to do call-setup Many H.323 systems don’t support rtp protocol Suggestion – consult the following web page: http://www.hep.net/hepnrc/video/video.html
- 20. Questions ???