packet video & audio tools on pc’s (a cookbook)
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Packet Video & Audio Tools on PC’s (A Cookbook). February 7-11, 2000 H.A. “Kipp” Kippenhan, Jr. [[email protected]]. Outline. Classification of systems Packet Tools - Background ITU Standards Applications Audio considerations Video considerations Additional suggestions Summary - PowerPoint PPT PresentationTRANSCRIPT
Feb 7-11, 2000 CHEP 2000 Slide 1 NetworkResourceCenter
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Packet Video & Audio Tools on PC’s (A Cookbook)
February 7-11, 2000
H.A. “Kipp” Kippenhan, Jr.
Feb 7-11, 2000 CHEP 2000 Slide 2 NetworkResourceCenter
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Outline
Classification of systems Packet Tools - Background ITU Standards Applications Audio considerations Video considerations Additional suggestions Summary Questions
Feb 7-11, 2000 CHEP 2000 Slide 3 NetworkResourceCenter
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Classification of Systems – Pre H.323
TCP/IP Netw ork
ISDN Netw ork
CampusLAN
H.320 PACKET(vic, rat)
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Classification of Systems – Post H.323
H.320
PACKET
ISDN Netw ork
TCP/IP Netw ork
CampusLAN
TCP/IP Netw ork
CampusLAN
H.323
CONNECTIONCIRCUIT
vic, rat
Feb 7-11, 2000 CHEP 2000 Slide 5 NetworkResourceCenter
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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
Feb 7-11, 2000 CHEP 2000 Slide 6 NetworkResourceCenter
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ITU Standards
H.320 umbrella standardVideo & 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)
Feb 7-11, 2000 CHEP 2000 Slide 7 NetworkResourceCenter
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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)
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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
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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)
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The Applications
Video toolsProvide 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)
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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)
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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)
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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 controlToo many level controls to tweak (especially with Windows)» On speaker» Sound card (software – in systray)» Application (slider bar in rat)
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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
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Audio Considerations
Windows 2000 now shipping » Don’t assume anything» Compatibility issues» Users must perform tests
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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
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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)
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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)
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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
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Questions
???