Videophones for the Internet

Microsoft Netmeeting
Netmeeting from Microsoft is an audio-visual teleconferencing and collaborative working tool that uses a mixture of TCP and UDP to manage connections and send audio/video data between multiple participants in a videoconferencing session.

We tested Netmeeting V2.0 between two PCs over a shared 10 Mbit/s Ethernet LAN, on the same subnet, with 2 Pentium 200MMX Pcs running Windows 95, each with a Connectix ColorCam 2.0, a microphone, sound-blaster and speakers.

The Video frame rate varied from about 3 frames per second for large image size best quality to about 8 for small image and fastest video so it looked jerky, but the video quality was more than adequate. The cameras used were Connectix ColorCam 2.0 and the frame rate seen in Netmeeting was slower than the rate that the camera supported, so it seems the limit was imposed by Netmeeting, and not the camera or CPU.
There are options to allow control of the video by setting the resolution of the sent image in steps of small, medium and large and to choose to trade off frame rate for image quality. These options also have an effect effect on bitrate, with the setting for receive best image quality having the greatest effect on bandwidth utilization. Choosing large image size tends not to change bitrate, but does effect effect frame rate.
The following snapshots show the best and worst image quality that can be achieved on the fastest (LAN) and slowest (14.4K) network settings, at the expense of bitrate and frame rate. Note that the small images have been shown at their x1 size and also enlarged x3 for comparison.




Tests were carried out the software configured to use a LAN as the delivery network, and also configured for a 14.4 Kbit/s modem (although still connected by Ethernet), to test best and worst delivery. There is an option at first start-up to specify the speed of the network, and it is also re-configurable under the tools/options menu without re-installation. Choices are :

I used a LAN analyser to see what the bitrate was for a range of settings and found that at the large image, best quality settings that the bitrate for a very animated (i.e. lots of motion and sound) two-way conference was averaging about 3% utilization which is 150 Kbits/s each way. With the worst quality settings, utilization was about .25% or 12 Kbits/second each way, indicating that a 14.4K modem could be used, althought the video quality is quite bad. A 33.3K modem would be better. The graphs below shows the percentage utilization of the 10 Mbit/s LAN bandwidth for a period of high activity followed by a period of low activity with the options set as specified. (NOTE: The scales for each trial are different) The conclusion is that lower bitrates and faster frame rates can be achieved by using smallest image size and lowest image quality.




The audio was acceptable once we got the microphones set up correctly, with a bit of lost sound now and then. There was an appreciable delay which depended on the processing power of the PC doing the sending, i.e. the audio from a Pentium 90 took about twice as long to arrive as the audio from a Pentium 200MMX. Lip synch was a bit hard to detect at the frame rates achieved, but there didn't seem to be too much disparity between the video and the audio.


We found the application sharing quite usable, both of us working on editing a Notepad document. One thing did irritate me, and that was the little sign "Click Mouse" that kept floating in front of the changes the other person was making, making it difficult to see what they were doing. I hope there's some way to stop that.

Another 'feature' that we found which was quite startling, and more than a little worrying, was the shared clipboard. (search for help on 'clipboard' in Netmeeting) Not only was it shared in Netmeeting collaborative documents, with the annoying result that if one of the other people in the meeting happened to copy something to what they thought was their clipboard then they overwrote whatever you thought was in yours, but we discovered by accident that it was shared even if you were working on a document not shared by Netmeeting, in fact nothing to do with Netmeeting. This means that if you have a Netmeeting running in the background and are busy cutting and pasting your email, for example, then the contents of your clipboard are accessible to others in the meeting, and they can copy it into their own documents, or even overwrite it if they happen to do a 'highlight CTRL-C' before you manage to do your 'CTRL-V'. A bit of a security hole, even if you know about it, because the 'cut and paste' paradigm is so natural now that a user doesn't even think about it.

Netmeeting uses the ITU H.323 standard for Visual telephone systems and equipment for local area networks which provides a non-guaranteed quality of service, and which should also allow it to interwork with other companies' equipment. It is supposed to work across ISDN, PSTN (using a modem) and other networks that can carry IP, such as Emulated LAN on ATM.

The Microsoft Netmeeting website has a downloadable document NMprodgd.zip - the netmeeting product guide. It contains a long list of videoconferencing companies that have registered with Microsoft as being Compatible Conferencing Products. Intel, PictureTel, VDOnet, White Pine are amongst the videoconferencing product manufacturers that have registered in this way.

Summary.

  • International standards based. ITU H.323 Click here to buy the standard, when ITU publishes it.
  • Impressive video quality, not so impressive frame rate, using the ITU H.263 video compression standard.
  • Impressive Audio quality using ITU G.711 and G.723.
  • Shares Microsoft applications and does file transfer.
  • Has a built-in whiteboard application.
  • Shared clipboard is troublesome.
  • Chat as a fallback if audio and video become unusable.
  • Adjustable video resolution at the sending end and zoom controls at the receiver.
  • Very adjustable network, image quality and frame-rate controls, though not independent.
  • Detachable, resizable, relocatable video windows, including self-view.
  • Free fully functional software downloadable from Microsoft
    NetSpeak Webphone
    Webphone from NetSpeak is an audio-visual teleconferencing system for use with the IP networks.

    We tested Webphone V3.0 between two PCs over a shared 10 Mbit/s Ethernet LAN, on the same subnet, with 2 Pentium 200MMX Pcs running Windows 95, each with a Connectix ColorCam 2.0, a microphone, sound-blaster and speakers.

    Network speeds can be set, without re-installation of the software, at 14.4, 28, 64, 128 Kbit/s and 1.5Mbit/s.

    Using a slider control, the user can adjust the received image from fastest motion/poor image to slow motion/best image quality. This affects bitrate as well as frames/second as and image quality, with higher network usage for the better image quality, despite lower frame rates at that setting.
    (Note that the frame rate for the 1.5Mbit/s connection actually went down rather than up for the 'receive fastest' selection. I suspect this is because the frame rate was not limited by the bandwidth, but by CPU)
    Frame rates varied from 1 fps up to 11, as measured by the Webphone software itself, for various settings of the network parameters and differences in motion, from still to frenetic, with the lowest frame rate corresponding to the 14 Kbit/s network speed selection, best image quality and fast moving subject. The highest frame rate was achieved using the 1.5Mbit/s network and the 'fastest motion' setting with a still subject. Paradoxically, it is possible to get this high frame rate only if nothing is moving, so it isn't of much use. The frame rate for this configuration drops down from 11 to 8 when the subject starts talking. Even at the highest network speed and with the fastest motion setting, lip movement with speech is poor and does not aid in understanding speech very much.
    The following snapshots show the video performance at 14.4Kbit/s and 1.5Mbit/s, with the fastest motion/best image selection as indicated. The snapshots show video frame rate and bitrate measurements for one direction of a high activity two-way conference.

    Note that the zoomed out image was set automatically by the software for the 14.4 fastest selection. I don't know how to stop it doing that, and I can't find any zoom control.

    The version of the software that we used for the tests was an 'unactivated' copy and it was limited to 3 minutes talk time, however I found that on an isolated subnet, i.e. a piece of co-axial cable connected between the two conferencing computers and no connections to the outside world, that the time-out did not occur.

    Latency of the video and audio (time delay taken to deliver to far end of conference) was quite noticable at about 500ms, although the sound was well synchronised with the video. This was on an isolated subnet with no router delays.

    Below are some measured traffic graphs showing two-way traffic for the two extremes of usage. The connection at 1/5Mbits/s and best image uses about 1.25% of a 10Mbit Ethernet LAN, which amounts to about 60 Kbits/s each way, when it is very active and about 0.2% or 20Kbits/s when nothing is moving and no sound is being transmitted.
    The 14.4 Kbit, (fastest motion)/(worst image) connection uses about .3% or 15 Kbit/s each way when there's lots of motion and about .1% or 5 Kbit/s when idle. This would indicate that a 14.4 Kbit/s modem could actually be used but a 33.3k modem should handle it much better.


    Webphone uses UDP and a proprietry protocal NSCP to carry the audio-visual information. It is supposed to work across LANS, WANS, ISDN, PSTN (using a modem) and other networks that can carry IP, such as Emulated LAN on ATM.

    Summary.

  • Uses UDP and a proprietry protocal NSCP to deliver audio and video.
  • Impressive video quality, using the ITUH.263 video compression standard.
  • Impressive Audio quality using ITU G.711 and G.723.
  • Relocatable video windows, not resizable. Includes self-view.
  • Has chat as a fallback.
  • Doesn't allow shared applications.
  • Automatic transmitted video zoom but no manual control. No receiver zoom.
  • Very adjustable network, image quality and frame-rate controls, though not independent
  • Free '3 minute Time-out' trial software downloadable from Netspeak
  • Activated licensed software inexpensive. (about $50 US)
    Visual Eyes from CyberSoft Corporation does NOT support the internet - this is a direct dial modem to modem based video phone product! The modem can be analogue or ISDN. This is a H.263 codec based system for windows95 ONLY.

    The following is a list of (currently available (29/1/98) Internet Videophone and Audiophone type products, some of which have been evaluated:

    Intel Internet Phone for Windows 95 is no longer available (the beta product was available for free). It has been replaced by
    Intel's ConnectedPC: Videophone. This product and Microsoft's NetMeeting can communicate.

    CallWiz Plus and CamWiz Windows 95 & 3.x Labtam Communications - Microsoft NetMeeting compatible.

    Cooltalk Windows 95 & 3.x, Windows NT, Sunos, Solaris, HP-UX, Digital Unix, IRIX.

    Cu-SeeMe Windows 95 & 3.x, Windows NT, Macintosh. White Pine's commercial versions of what was a free macintosh videoconference product. The latest versions are more standards based, including support for the H.323 videoconferencing standards when used with the new MeetingPoint conference server from White Pine. MeetingPoint lets any standards-based client (including CU-SeeMe Version 3.1) communicate with each other. This means that users of Microsoft's NetMeeting, Intel's Internet Video Phone, CU-SeeMe V3.1, and others can all join together in group videoconferences. CU-SeeMe ver. 3.1 for win95 was an easy to install product (demo download version was used) and provided quite reasonable performance between Monash University in Victoria, Australia and Staffordshire University, England.

    Digiphone by Third Planet Publishing for Windows 95 has been superceded (but seems to be available still) by a complete 'system' with hardware and software combined. See Digiphone USA Desktop Videoconferencing - VideoTalk(TM) for a description of the updated software/hardware system. Win95 and Mac systems are being developed. The earlier e-Phone Macintosh product has been developed into the Digiphone for Macintosh product.

    Free Phone is an audio phone for the Internet developed by members of the High-Speed Networking group at INRIA. It is built around the RTP internet protocol and other standards. It is available for Solaris 2.5, SunOS 4.1.3, Linux 2.0, FreeBSD 2.2 and Windows95. To quote their website:

    "FreePhone includes a number of interesting features
    • Management: Support for multiple concurrent unicast and multicast conversations, FreePhone "white pages" on the Web, simple call protocol.
    • High quality audio capture: Up to CD/DAT stereo quality capture, wide panoply of coding schemes.
    • High quality restitution: 3D/spatial rendition of audio sources (this feature is used in conjunction with the MiMaze distributed (multicast) game to enhance the sense of immersion in the game and to add live 3D voice interaction between players -- however the feature is not available on the public release of FreePhone yet).
    • Adaptation to network conditions: Includes a rate control mechanism (adaptation to available bandwidth), a FEC-based error recovery scheme (adaptation to and recovery from loss process in the network), and an adaptive playout adjustment scheme (adaptation to delay variations). "
    FreeTel FreeTel Communications, Inc. - Free audio internet telephone (full duplex) for Windows 95 & 3.x

    IBM's Java Phone Some of the features of this internet audio phone as found on their website:

    • "The first Java H.323 compliant IP-based phone. Meets industry standards, including RTP streaming,
    • H.323 signaling, G.711 and G.723 codecs.
    • Interoperates with Microsoft NetMeeting™ and H.323 PSTN GateWay.
    • Supports full duplex voice transmission." Windows 95 only, OS/2 on the way (as at 29/1/98). IBM also have IBM Internet Connection Phone for windows95,NT and OS/2
    Internet Phone by Vocaltec for Windows 95 & 3.x, Macintosh. Full featured internet telephony, the company also has other IP based products such as pc to phone software and gateways, as well as atrium which is advertised as a Real-Time multiparty audio over internet (to computer or normal phone) product.

    Net2Phone PC to Phone Internet Telephony for Windows 95 & 3.x. This is a system that uses the internet to talk to IDT Corporation's central hardware (telephone exchanges/switches) and then uses thier telephony network for local call placement. Also in the USA, they now have a net2phone-direct product which replaces the pc hardware. All of this requires the user to subscribe to their service. This is an OUTGOING call only service.

    Speak Freely John Walker's audio phone. Complete with source code for Windows 95 & 3.x, Windows NT, UNIX. has some useful links to protocol information.

    VoxPhone by Voxware for Windows3.x, 95 & NT. Look in the products section for details. Part of their description for the product is: " VoxPhone 3.0, the new H.323-compliant version of Voxware's standards-based Internet telephone software.

    "VoxPhone provides real-time, high-quality voice connections between one or more users over IP networks such as the Internet. You can place calls, conduct conferences of up to five users, or send voice messages to any VoxPhone user in the world for the price of a local Internet connection. H.323 Standards Compliance (Interoperability with Netscape Conference, Microsoft NetMeeting and Intel Internet Phone) "

    VDOPhone by VDO, Video Conferencing for Windows 95. Part of their product description:

    "With the VDOPhone Internet version, calls are placed over the Internet or an Intranet, so you can talk to people for an unlimited time without having to pay telephone toll charges. The VDOPhone Professional version has all of the same features as VDOPhone Internet, but it can also direct dial standard telephone numbers."