This chapter is designed to help you troubleshoot any problems you may run into while running INTV! and also answers some common questions the user may have.

The chapter discusses:

• Common questions regarding video
• Common questions regarding audio
• The INTV! Station
• The INTV! Media Chooser
• Questions about Licensing

Many problems that you may encounter while using the INTV! software are network-related. INTV! uses some important, low-level networking functions that other programs may not use. For this reason, many irregularities in network configuration do not manifest themselves until you attempt to use INTV! or other network-intensive applications. The following questions and answers should solve most networking issues that you encounter while using INTV!.

Are there any active Stations on your network? Stations may be activated and deactivated by the administrator from time to time. Verify that they have been activated.

Multicast routing must be installed on your workstation. A multicast route must also be added in order for multicast to work properly. As root, you should execute the following command if you have not added a multicast route already:

route add 224.0.0.0 <workstation name> 0

Is your Station Index up-to-date? Try activating the Locate TV Stations button from the Station Index to update your station listing.

Is the Station located on another physical network? If the Station is located on a different network, the Chooser may not be able to detect the Station. You will need to add the Station to the index manually. See Chapter 8, "The INTV! Media Chooser", for information.

Are you attempting to operate through security blocks or network firewalls? Some sites have installed special network equipment that restricts the flow of data from one area to another. INTV! may not be able to communicate correctly through these types of security equipment.

On Microsoft Windows machines, make sure that each PC can contact the machines that are set up as stations. Most TCP/IP stacks provide a utility called ping that can be used to test connectivity. Verify that the machine with the viewer can ping the station. A successful ping indicates only that a minimal level of networking infrastructure is working; there could still be problems.

If you are using a Microsoft Windows machine and you have multiple network cards installed in your PC, verify that you have selected the proper one and that you are connected to the network that the INTV! Stations are broadcasting on. 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. You must also make sure that each network card has its IP address, subnet mask, and default gateway set properly.

If the station you wish to tune is connected to you 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 1 MB in size) both ways across any routers. If you see any time-outs, INTV! 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.

Station administrators can select from a list of several video compression algorithms. The following compression algorithms are supported by the INTV! Viewer for Windows:

CellB—CellB compression was developed by Sun Microsystems to support compression and decompression of video with minimal hardware requirements. CellB is supported by all INTV! Stations.

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 a video compression standard developed by the International Telecommunications Union. H.261 is designed to provide maximum quality while at the same time minimizing bandwidth usage. Like JPEG, compression and decompression of H.261 streams requires considerable processing power and works best if your video hardware supports this standard or you have a high performance workstation.

The viewer does not have to support hardware decompression of the station’s compression type since the INTV! software can use software decompression techniques (except where noted) if no hardware is available.

Due to network performance issues and video compression limitations, your video may appear slightly choppy. If your video is uncharacteristically slow, however, there are several things you should check.

What is the quality of the source video signal being used at the TV Station? If the incoming video signal quality is poor and full of static, the compression algorithm can not function properly. You should try to obtain a more stable video signal. If the quality of your input signal cannot be improved, reducing the frame rate and video frame size may improve performance.

What frame rate has been set for the TV Station? Each TV Station can control the speed at which they are sending video information. You will want to verify that the TV Station’s frame rate is at the appropriate level.

What other applications are in use while video is running? If the frame rate is high, slower workstations may not be able to reproduce the desired frame rate. This is especially true if other processes are using up workstation resources. Reduce the number of other applications running on that workstation.

Is network traffic high? If network traffic is high, images may take longer to reach your workstation.

Do you have enough RAM and SWAP space? See Chapter 1, "System Requirements", for more information.

Which port on your video board is the TV Station using for input? Verify that the TV Station is using the video port you have plugged the video source into.

Has video transmission been disabled on the TV Station? Each TV Station administrator can toggle video and audio transmissions separately. Some stations may be designated as "Radio Stations" that purposely broadcast only audio.

Is there a problem with your video equipment or cabling? Verify that the video source is connected to the TV Station 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.

What is the viewer’s brightness level set on? If the viewer’s brightness level is too low. you may only see a blank video screen.

What is the TV Station’s video TTL value? Video TTL controls how far video is propagated throughout your network. Verify that the TV Station’s video TTL value has been set high enough to reach your workstation. See Appendix A, "Technical Issues", for more information on TTL.

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, INTV! 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. 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.

What compression settings have been selected on the INTV! Station? Stations have control over their video settings. The station administrator 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.

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

What is the Station’s audio record gain? If the audio gain is set too high, you will get audio distortion, clipping, and extremely high volume levels.

Each INTV! Station has control over its own sending volume. Ask the administrator to reduce his or her station’s sending volume.

Check to make sure that you have the volume set to an appropriate level on the Media Chooser or on the Viewer on Windows machines.

What is the level of the input audio signal? If the level is too high, it will overload the Station’s audio inputs causing distortion. See the section on Connecting Audio Equipment in Chapter 2, "Installing Optional Hardware", for information regarding audio equipment.

First, check to make sure that you don’t have your audio muted by mistake.

Has audio transmission been disabled on the Station? Each Station administrator can toggle video and audio transmissions separately. Some stations may be broadcasting only video.

Is there a problem with your audio equipment or cabling? Verify that the audio source is connected to the Station properly. Try using another audio source or connect your audio source to another output device such as a speaker to verify that it is operating properly. See the section on Connecting Audio Equipment in Chapter 2, "Installing Optional Hardware", for information regarding audio equipment.

Is the Audio Active button selected for the current viewer? Each viewer features an Audio Active button that will disable and enable audio for that viewer. Verify that audio is active on your viewer. Note that it may take a few seconds to "reactivate" audio once it has been deselected.

Which audio output device has been selected in the Audio Control panel? If headphones have been selected as your audio output device, you will not hear audio from your workstation’s speaker.

What is the Chooser’s volume level? Check the Audio Control panel and try adjusting the TV Volume setting.

What is the Station’s audio TTL value? Audio TTL controls how far audio is propagated throughout your network. Verify that the Station’s audio TTL value has been set high enough to reach your workstation. See Appendix A, "Technical Issues", for more information on TTL.

What is the Station’s audio silence threshold? If the audio silence threshold has been set too high, the Station audio will be clipped or muted entirely.

If you are using an external speaker box, is it muted? If there is an orange light lit, then you have muted your speaker box. Press the box’s mute button to toggle the speaker back on.

If the Station is using a speaker box, incoming audio should be connected to the microphone-in port, not the line-in port.

The INTV! Station may have its Silence Sensor level set too high. Often, as people 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 you are using external speakers, a buzzing sound could be caused by electrical interference. If you can not eliminate the source of the interference, 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 audio to send data 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.

Yes. You can run both the station and viewer software simultaneously.

No, currently the architecture is designed around one INTV! Station per workstation.

Something or someone else is using a required input device. If you are seeing device busy errors, it means that another application has control over either the audio channel or the video device. Verify that you have selected the correct video device for the INTV! Station. Try rebooting the workstation if possible.

You can create "Radio Stations" by disabling video transmissions from a station and connecting only an audio signal. You don’t even have to have a video board installed. A station sending only audio does not require much processing power or bandwidth.

IP multicast is a networking technology that reduces duplication of network data. Most networking schemes would send a copy of a station’s audio and video signal to each receiver using the INTV! Viewer. If you have 11 people viewing an INTV! broadcast, then normal TCP/IP would have to send out 11 video signals and 11 audio signals. Multicast enables INTV! to send out only one stream of video data and one stream of audio data regardless of the number of viewers. With multicast there is no duplication of data and wasted bandwidth. See Appendix A, "Technical Issues", for more information on IP multicast.

Although INTV! uses data compression and multicast technology to minimize the amount of data sent across the network, TV Stations can still use a fair amount of bandwidth. There are several factors you can adjust to control the amount of data transmitted by the TV Station.

• Video Frame Size—The larger the video frame size, the more video data must be transmitted across the network. Users may obtain acceptable images from a smaller video frame size by using the zoom feature of the INTV! Viewer.
• Video Frame Rate—Bandwidth usage is directly proportional to the video frame rate. Reducing a TV Station’s video frame rate can greatly reduce network bandwidth consumption.
• Timeout—Keep the timeout set to a minimum to avoid broadcasting data when nobody is watching.
• Video and Audio TTL—Keep the TTL value at a minimum to avoid broadcasting to networks that will not be using the INTV! software.
• Audio Silence Sensor—Keep the silence sensor at a minimum to avoid broadcasting "silence".

You can restore an INTV! Station to the factory default configuration by removing the station’s configuration file, /etc/insoft/INTVStation.ini. After deleting the configuration file, you will need to reassign a station number and station description. All other settings are restored to their factory defaults.

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