Packet Video

1
Packet Video Audio Tools on PCs (A Cookbook)

• February 7-11, 2000
• H.A. Kipp Kippenhan, Jr.
• kippenhan_at_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 PCs

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)
• Whats 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
• Doesnt 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 wont 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
• Dont 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 PCs)
• 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
• Theres still life in your H.320 (ISDN based)
  codec
• New codec purchases should support both standards
  H.320 H.323 (e.g. - Polycom Viewstation)
• MCUs (e.g. Accord MGC-100) will support hybrid
  meetings (mixture of H.320 H.323 devices)
• IP firewalls and H.323 devices dont interoperate
  well (it takes some tuning)

19
Summary

• Vic (H.263) and rat (G.728) support necessary
  standards why dont H.323 systems interoperate
  with VRVS?
• No way to do call-setup
• Many H.323 systems dont support rtp protocol
• Suggestion consult the following web page
  http//www.hep.net/hepnrc/video/video.html

20
Questions

• ???