Appendix A

Troubleshooting

Overview

This section will address some common problems and answers some questions that may be encountered when using the Communique! software. If after examining this section you are unable to solve your problem, please refer to section "MDL Technical Support" in the Welcome chapter on page 2 for information on obtaining technical support.

Common Questions about Networking

Many problems that you may encounter while using the Communique! software are network related. Communique! uses some important, low level networking functions that many other programs may not require to function. For this reason, many irregularities in network configuration do not manifest themselves until attempting to use Communique! or other network intensive applications. If you are experiencing problems operating the Communique! software, here are a few areas that you may want to investigate.

Why can’t I locate other conference members?

Try switching to the From Notebook and then back to the From Network list in the Start Conference panel to update the list of available conference members on your local network. The list is updated each time you bring up the From Network list.

If there is heavy traffic on your network it is possible that all available network users may not be detected. You can try reselecting the From Notebook list several times until your party appears.

Communique! will locate other possible conference members on your local network automatically. When traveling to remote and secondary networks, the message used to detect other Communique! users may not reach users on remote networks. If you are attempting to contact someone on a remote or secondary network beyond this range, that person may not appear in the Start Conference control panel and will have to be added with the Custom Address entry, as described in the "Conference Manager" chapter of the Communique User’s Guide. In any case, Communique! must be able to contact the host PC of those persons with whom you wish to conference.

Why can’t I contact a remote conference member?

Make sure that each PC can contact all other machines that will be involved in the conference. Most TCP/IP stacks provide a utility called ping that can be used to test connectivity. Verify that each machine can "ping" the other machines that you need to conference with. A successful "ping" indicates only that a minimal level of networking infrastructure is working; there could still be problems.

What Network Card Settings Should I Look At?

If you have multiple network cards on your PC, verify that the network you will be conferencing on is up and running. Make sure that the hostname assigned to each network card is unique and configured correctly. If you have multiple network cards installed, each one will require a unique IP address.

Make sure that your network cards are set up properly. Use the Network Setup utility to show you the current settings. Make sure each network card has its IP address, subnet mask and default gateway set properly.

What if I am using a router?

If the machines involved in the conference are connected through a router, the router must be able to pass TCP and UDP packets. Many routers have an option to block specified packet types. Make sure the above types are enabled in both directions.

If you are running through a router, make sure that the router can keep up with large amounts of data. You can test this by ftp’ing a large file (at least 1MB in size) both ways across any routers. If you see any time-outs, Communique! may have problems as well. This especially applies when you are routing from a high speed network (such as ATM or FDDI) to a slower network (such as Ethernet). Sometimes routers cannot do packet size conversions quickly enough.

Common Questions about Licensing

Why do I get "Not a Valid License" errors?

There is a problem with the license number you have entered. Examine the license number of your software which can be found on your Communique! disk. Make sure that you entered the complete license number exactly.

Why do I get "License Violation" errors?

This message indicates that another user has attempted to use Communique! software that has been assigned the same license as your PC. In this situation neither PC will be able to use the Communique! software. The license you received with your software is unique to your PC and cannot be installed on multiple systems. You will need to remove the Communique! software and license from one of the PCs to continue.

Common Questions About Video

What compression algorithm does Communique! use?

This depends on the type of compression selected in the TV Tool. The compression schemes that you can select from depends on the type of video capture board installed on your PC. The currently supported compression options are:

CellB—CellB compression was developed by Sun Microsystems to support compression and decompression of video with minimal hardware requirements. CellB is supported by all Communique! platforms. The MDL CellB codec for the PC has the ability of transcoding. This means that it can recompress video that has already been compressed with another format.

DVE2—DVE2 compression was developed by MDL to support compression and decompression in software. DVE2 provides a high level of image quality by taking advantage of today’s more powerful processors. DVE2 is currently available to PCs only. The MDL DVE2 codec for the PC also has the ability to do transcoding.

Indeo—Indeo is a video codec developed by Intel. Indeo provides high image quality and very efficient software decompression. However, Indeo does not lend itself well to compressing in software, so generally you will want to use this format only if your video capture card supports Indeo compression in hardware. Indeo is currently available to PCs only.

JPEG—JPEG, developed by the Joint Photographic Experts Group, generally produces the highest quality video image, but requires more processing power than other compression algorithms. Unlike Indeo, JPEG requires substantial processing power to decompress in software so you will generally want to use this format only if your video capture card supports JPEG compression and decompression or you are using a fast workstation.

H.261—H.261 is the telephony video compression standard developed by CCITT. H.261 works by first selecting the bandwidth available for video and the desired frame rate. The video is then compressed to fit into the given constraints. H.261 on a workstation is a software compression and decompression algorithm that requires substantial processing power.

The receiving conference member does not have to support hardware decompression of the sender’s compression type since the Communique! software can use software decompression techniques (except where noted) if no hardware is available.

Why does the video I receive seem slow?

If your video is uncharacteristically slow there are several things you should check.

What is the quality of the source video signal being sent to you? If the incoming video signal quality is poor and full of static, the compression algorithm cannot function properly. The sender should obtain a more stable video signal. If the quality of the input signal can not be improved, reducing the frame rate and video frame size may help improve performance.

What frame rate has been selected in the sender’s TV Tool panel? Each person in the conference has control over her or his own sending frame rate. The remote conference member may have purposely (or accidentally) selected a slower frame rate.

What other applications are in use while the Communique! TV Tool is running? If the frame rate is high, slower PCs may not be able to reproduce the desired frame rate. It is not recommended to run other applications while Communique! is running.

Is network traffic high or available bandwidth constrained? Bandwidth limitations or an increase in ambient network traffic will reduce the amount of information that can be sent out to the conference.

Does your PC have enough RAM and meet the other requirements for Communique!? See the "System Requirements" chapter of the Communique! User’s Guide for your PC’s requirements.

If you are receiving JPEG video and do not have a video card that supports hardware decompression of JPEG you will experience reduced performance. Ask the sender to select CellB as their sending compression.

Why can’t others see my video?

If your video capture card has multiple video inputs, have you selected the correct one from the TV Tool?

Have you disabled video transmissions from the TV Tool? You must click on the TV Tool’s broadcast button or select Send to begin sending video from your PC.

Have you selected the desired conference member(s) to receive video from the TV Tool’s Recipients? You should verify that the user not receiving your video is selected in the Recipients list.

Stop your video momentarily and enable the Preview option and verify that your video card and equipment is functioning properly.

Is there a problem with your video equipment or cabling? Verify that the video source is connected to your video card properly. Try using another video source or connect your video source to another output like a television display to verify that it is operating properly.

Have you correctly installed your video board and any necessary drivers? Most video capture boards come with demonstration or test programs that you can use to verify correct installation of the video board. Refer to the manufacturer’s documentation for information on installing the video board.

Which format of video compression are you using? If you are sending Indeo video, UNIX workstations and PCs without Video for Windows will not be able to see your video.

There may be a problem with the configuration of the network. Verify correct network configuration as outlined in the "Common Questions about Networking" section.

Why does the video I receive seem distorted or grainy?

Check that Windows has been configured with a video driver suitable for your video card. You will want to use a display format that supports at least 256 colors. A 16-color VGA driver isn’t optimal for use with video.

To conserve network bandwidth and increase the frame rate of video, Communique! employs various types of data compression techniques. The compression algorithms that the sender can use will depend on the type of video board that they are using. Indeo or JPEG generally will produce the best quality video, but takes more bandwidth and may require specialized hardware to decode. Ask the sender to choose a different compression method to view your options.

Be aware that not all video boards are alike. Some video cards such as MovieMan produce a different level of video quality than boards such as the VideoBlaster. The quality of image is directly related to the compression and display hardware contained on the card.

What compression settings have been selected on the sender’s TV Tool? Each person in the conference has control over her or his own video compression settings. The remote conference member may have purposely (or accidentally) selected a higher compression setting, which could have a dramatic effect on image quality.

What is the quality of the source video signal being sent to you? If the incoming video signal quality is poor and full of static the received image will be poor. The sender should obtain a more stable video signal.

Why do I see color flashing when I move among windows?

When running Windows in 8-bit display mode, the video image must share a color palette with all other applications. Since there are only 256 colors available, the video window sometimes must create its own private colormap, active only when the window is selected. You may experience color flashing in the TV Viewers and Video tools in this case. If your PC has the ability to run in a display mode that offers more than 256 colors you may be able to eliminate this behavior completely. However, unless your PC is extremely fast and is equipped with a local bus video board the reduction in performance may not be worth it.

Common Questions About Audio

Why does the audio I receive seem so loud?

Check your audio board’s Mixer settings for playback volume. This option controls the volume level of the audio you hear. Reduce the playback volume to a reasonable level.

If you are using an external speaker make sure the volume is adjusted to a reasonable level.

Each person in the conference has control over their own input volume. Ask the person to reduce his or her sending volume. Input volume is controlled from your audio board’s Mixer.

Some microphones feature an adjustable gain control. If the sender is using such a microphone and adjusting the sending volume has little effect, ask them to reduce their gain to a reasonable level.

What is the level of the sender’s input audio signal? If the level is too high it will overload the PC’s audio inputs producing a loud muffled sound or severe clipping. This situation can occur if they are using audio input from a line level device such as a VCR connected through the microphone-in port of the workstation. See the section "Audio Input Devices" section in the Installing Optional Hardware chapter of this guide for more information.

Why don’t other people in the conference hear me?

They should watch their Audio tool’s meter to see if they are not receiving audio or just cannot hear it. The Audio Tool’s meter shows a colored bar that shows the level of incoming video. This is very helpful in tracking down the problem.

You may have muted your audio from the Audio Tool. Bring up the Audio Tool and verify that the Send Audio option has not been disabled.

Your input volume may be too low. Adjust the input volume level with the Mixer included with your audio board.

The remote conference member’s playback volume may be too low to hear you. Have conference members verify that their playback volume has been set to a reasonable level in their audio board’s Mixer. Have them check the connection and volume setting of any external speakers they are using.

Have you selected the desired conference member(s) to receive audio from the Audio Tool’s Recipients? You should verify that the user not receiving your audio has been selected in the Recipients list.

They may be refusing your audio. Have them check their Audio/Video Receiver and verify that they have elected to receive audio from you when available.

Your microphone may not be hooked up correctly, or may be defective or in need of a new battery. Verify that the microphone is on and plugged into the microphone-in port of your audio board. If available, you can use enable Local Monitor from your audio board’s Mixer to verify that your microphone is functioning properly.

You may have selected the wrong input device. Check your audio board’s Mixer and verify that you are using the selected input device.

Your Silence Sensor may be set too high. Try reducing the level of the Silence Sensor from the Audio Tool.

Why don’t I hear other conference members?

You should watch your Audio tool’s meter to see if you are not receiving audio or just cannot hear it. The Audio Tool’s meter shows a colored bar that shows the level of incoming audio. This is very helpful in tracking down the problem.

Your playback volume may be set too low to hear other conference members. Verify that your playback volume is set to a reasonable level in your audio board’s Mixer.

The remote conference member may not be sending you audio. Have them check their Audio Tool’s Recipients list and verify that you are being offered audio.

You may have not enabled audio playback from the Audio Tool. Verify that audio playback has been turned on.

You may be refusing their audio. Check your Audio/Video Receiver option and verify that you are accepting audio from that person.

The remote conference member may have a problem sending audio. Refer to the section Why don’t other people in the conference hear me?.

Your speaker may be defective or your external speaker box hooked up incorrectly. Verify that the speaker or speaker box is functioning correctly.

If you are using an external speaker, is it on? Verify that it is connected properly. If it uses batteries, are they dead?

There may be a problem passing audio data through the network. Refer to the section entitled "Common Questions About Networking" to verify that your network is functioning properly.

Why do I hear an echo of myself or feedback?

This situation occurs when your voice is picked up from a remote user’s speaker by her or his microphone and retransmitted into the conference. This loopback can be minimized and prevented in several ways.

Ask the remote conference member to move his or her microphone away from the speaker. If they are using an external speaker, have them point it away from the microphone.

Reduce your Sending Volume or have the remote conference member reduce her or his playback volume to decrease the likelihood that the microphone will pick up the sound from the speaker.

Ask the remote conference member to raise his or her Silence Sensor. This will decrease the likelihood that the remote microphone will pick up sound from the conference member’s speaker.

Try increasing the Echo Cancellation value from the Audio Tool’s Advanced settings.

If you are unable to correct the echo situation, you may want to consider using external headphones instead of sending audio through a speaker.

Why does the audio sound choppy or clipped?

Make sure that the person using the microphone is directing her or his voice towards the microphone and from no more than a foot away. Most high quality microphones, including those available directly from MDL, are unidirectional. Unidirectional microphones only pick up sound whose source is directly in front of them. If you turn your head from side to side or walk around the room the microphone will not pick up your voice.

The person sending audio may have his or her Silence Sensor level set too high. Often, as conference participants speak, their voices drop down in volume on some syllables, especially at the ends of words. The Silence Sensor will recognize these dips in volume as "silence" and not send them to the other conference members. Ask the person whose audio is clipping to reduce the level of his or her Silence Sensor.

If there are several other people involved in the audio conference it is critical to properly set the Silence Sensor control to the proper level. Watch the Audio Tool’s audio meter. You should set the Silence Sensor just above the level of ambient noise.

Why do I hear lots of background noise or constant humming?

What type of microphone is being used? Lower quality microphones are often omnidirectional. Omnidirectional microphones pick up sound from all directions, and are likely to give unsatisfactory results. MDL strongly recommends purchasing a high quality, unidirectional microphone.

Some low quality or damaged microphones are not adequately grounded. This could cause a constant humming sound to be input into the conference. Try to locate the offending equipment and replace it.

If you are using external speakers a buzzing sound could be caused by electrical interference. If you cannot eliminate the source of the interferences try reducing the treble controls (if available) to reduce high frequency noise.

The Silence Sensor level of the person sending audio may be set too low. The Silence Sensor allows the microphone to send audio only above a given threshold, ideally when someone speaks. By raising the level of the Silence Sensor, you can filter out a good portion of the low level background noise.

How Can I Minimize My Bandwidth Consumption?

By reducing the amount of network traffic you generate, you can speed things up for other network users, and increase Communique!’s performance. There are several things that can be done to reduce the amount of network bandwidth that you use.

Video Frame Size—The larger the video frame size, the more video data that must be transmitted across the network. Lowering frame size reduces network traffic. Shrinking the video window size will also give you more space on the desktop.

Video Frame Rate—Bandwidth usage is directly proportional to the video frame rate. Reducing the frame rate can greatly reduce the amount of traffic being generated.

Video Compression—By increasing the amount of compression being used on your video signal, you can significantly reduce the amount of bandwidth you consume. Increasing the amount of compression will reduce the quality of the video image, but often a slight increase in compression will yield dramatic bandwidth reduction with only a modest decrease in image quality.

Silence Sensor—Keeping the Silence Sensor set as high as possible (so that you are not transmitting audio data when you are not speaking) lowers the amount of network traffic you generate. You must of course avoid setting it too high or you will affect audio quality.

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