Telephony Integration and Conferencing
Telephony Integration and Conferencing |
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Users of H.323 or multicast conferences might encounter problems connecting with other users or receiving audio or video.
If audio problems occur in H.323 or multicast video conferences, the microphones or sound cards on the client computers might be incorrectly configured or malfunctioning.
To diagnose sound hardware on client computers, start the Sound Recorder application by clicking Start, pointing to Programs, Accessories, Entertainment, and then clicking Sound Recorder, or by typing sndrec32 at the command prompt. Make a recording of your own voice using Sound Recorder, and then play it back. If there is no sound, check if the microphone is properly plugged in.
If the Sound Recorder test works properly but you continue to have audio problems, verify that the sound settings are correct on all client computers.
To verify sound settings through Volume Control
Note
A single incorrectly configured computer can cause audio problems or echoes for all other conference participants.
If you continue to encounter audio problems after adjusting the sound settings, check if the affected computers have full-duplex sound cards. Full-duplex sound cards are capable of capturing and playing audio simultaneously, while half-duplex sound cards can only do one at a time. Most modern sound cards are full-duplex, but many older sound cards are only half-duplex.
To check if the sound card on your computer supports full-duplex audio, start Sound Recorder and record a speech sample for approximately thirty seconds. After this is complete, open a second instance of Sound Recorder. Play the sample you recorded using the first instance of Sound Recorder, and while this is playing, attempt to record a sample using the second instance of Sound Recorder. If the second instance of Sound Recorder is unable to properly record a sample while the first instance is recording, the sound card does not support full-duplex audio, and thus will not work with TAPI.
If sound is distorted or otherwise continues to malfunction after you attempt the above procedures, there is most likely a problem with the microphone, sound card hardware, or sound card driver. Check with the manufacturer of your sound cards to ensure that you are using the most recent Windows 2000 drivers. Also, replace the microphones and sound cards on affected computers and attempt these tests again.
Audio echo is a common problem with audio conferencing systems. It originates in the local audio loop-back that happens when a user's microphone picks up sounds from their speakers and transmits it back to the other participants. Normal conversation can become impossible for other participants in the conference when very sensitive microphones are used, speaker level is high, or the microphone and speakers are placed in close proximity to each other.
One of the easiest ways to completely eliminate audio echo is to use audio headsets. These work by eliminating the possibility of a user's microphone picking up sound that is being received from other conference participants.
A more expensive solution is to use special microphones with built-in echo-canceling capabilities. These microphones detect and cancel out echo. The main advantage to these is that users do not have to wear headsets. Echo-canceling microphones are also a necessity for conference rooms because using headphones is not a practical solution.
If the video image of an H.323 conference participant cannot be seen by the other party, or if the image of a multicast conference participant cannot be see by all of the other endpoints, the computer's video capture device might not be working properly. When using Phone Dialer, participants should be able to see their own video image whenever they participate in videoconferences. If this is not the case, run the camera troubleshooter included in Windows 2000 Professional Help.
Audio and video problems in multicast conferences can also be caused by multicast issues. The following sections describe how to diagnose and resolve these problems using the MCAST tool included in the Resource Kit.
Problems in multicast conferences can be caused by incorrect network configuration.
To verify router configuration for multicast
Detailed router configuration data is usually available from the router vendor. Certain publications also contain information describing the configuration of routers and how the underlying protocols work.
If you are uncertain whether your network is configured to send and receive multicast packets, use the MCAST diagnostic tool. MCAST can send and receive multicast packets, helping you to determine which parts of your network are enabled for transmission of IP multicast packets. You can use this tool in send mode to set up multicast sources at different locations on your network, and in receive mode to determine the locations at which multicast traffic from these sources is being received.
To run MCAST as a multicast sender, use the following command-line on your Windows 2000–based computer:
MCAST /SEND /INTF:172.31.253.55 /GRPS:230.1.1.1 /INTVL:1000 /NUMPKTS:3600
MCAST will start sending multicast packets from the IP address 172.31.255.255 to the multicast group IP address 230.1.1.1 at the rate of 1 packet per every 1000 milliseconds. A total of 3600 packets will be sent over a one-hour period.
To run MCAST as a multicast receiver, use a command-line as follows:
MCAST /RECV /INTF: 172.31.255.255/GRPS:230.1.1.1
MCAST will start listening for multicast packets on its IP address 172.31.255.255 for the multicast group IP address 230.1.1.1. Received packets are displayed on the screen:
Started.... Waiting to receive packets...
Received [1]: [GOOD] SRC- 172.31.253.55 GRP- 230.1.1.1 TTL- 5 Len- 256
Received [2]: [GOOD] SRC- 172.31.253.55 GRP- 230.1.1.1 TTL- 5 Len- 256
Received [3]: [GOOD] SRC- 172.31.253.55 GRP- 230.1.1.1 TTL- 5 Len- 256
Received [4]: [GOOD] SRC- 172.31.253.55 GRP- 230.1.1.1 TTL- 5 Len- 256
Received [5]: [GOOD] SRC- 172.31.253.55 GRP- 230.1.1.1 TTL- 5 Len- 256
If you are unable to publish multicast conference invitations, set up Site Server ILS Service. The Site Server ILS Service is an essential component of TAPI IP Multicast Conferencing. This server represents the meeting place where conference creators and participants go through their client software application to find the information they need to participate in a conference.
When a conference originator creates a new conference, the Windows Phone Dialer software automatically creates a conference object on the selected ILS server. Participants who are granted access to this conference by the conference originator can see the conference from their Phone Dialer's view pane, and join it by double-clicking the conference name.
For documentation about installing ILS, refer to Windows 2000 Server Help.
The Windows 2000 Phone Dialer application must know the location of the Site Server ILS Service to provide conference creation and joining facilities.
The Phone Dialer application can locate this information in Active Directory if the following conditions are fulfilled:
Using Active Directory in this way means that users do not need to know the location of the ILS server on their network or manually enter that information into their Phone Dialer application. This makes using IP Multicast Conferencing with Windows 2000 easier for client.
For more information about installing domain controllers and the Active Directory, see Windows 2000 Server Help.
All of the Windows 2000 components required to support TAPI Multicast Conferencing on a client computer are installed, by default, in Windows 2000 Professional and Windows 2000 Server. However, in order for a computer or a user to use TAPI Multicast Conferencing, they need to be added to a Windows 2000 domain. If machine or user accounts for Windows 2000 domain are not created, users cannot access Active Directory and will need to add their ILS servers to the Phone Dialer application manually.