Chapter 12

TV Tool

Overview

Communique! provides users with motion video, enabling users to conference face-to-face across a LAN or WAN. The TV Tool is used to send video to other users, and to receive video from other conference members. The TV Tool also supports multicast routing to conserve network resources in multipoint conferences. The TV Tool Lite, a limited version of the TV Tool that can receive video but cannot send it, is bundled with the Communique! Lite and Audiograph packages.

In this chapter, you learn about

Other topics covered are

Starting a Video Conference

Before You Begin

Before joining a conference, you should check your setup.

1. Your video capture card should be installed properly in your machine.

2. Appropriate software drivers for the video card(s) should be installed, and you should verify that they work properly.

3. A video source (camera, VCR, etc.) should be properly connected to your video capture card.

TV Tool Lite does not require a video capture card or drivers.

Sending Video

By default, you will automatically start sending video to conference members as soon as you join a conference. However, this setting can be changed in the Preferences window. Before you join a conference you should check to make sure that the TV Tool is set up properly.

To begin videoconferencing:

1. Launch the TV Tool from the Conference Manager.

The TV Tool window will appear. From the main TV Tool dialog, you can set such characteristics as compression, size, and frame rate for your broadcast video. These controls are disabled for TV Tool Lite.

2. Check that Video Board and Compression selections are correct.

3. Make sure that you have your frame rate and frame size set properly.

When you set your frame rate and frame size, you should take into consideration the amount of network resources and system resources that they will consume.

When you join a conference, you will start sending video to all other conference members automatically. If you do not wish to use the video Auto Start feature, you can deselect it from the TV Tool Preferences dialog, which can be launched from the Options menu.

Unless otherwise specified, Communique! sends your video to all conference members. You can set the TV Tool to only send to specific members. By default, you will also accept video from any other conference participants who are sending video.

Later sections in this chapter, which describe in detail both sending and receiving video, discuss selecting who you wish to send video and receive video from.

Receiving Video

When you begin receiving video from another member of the conference, a panel will appear on the screen displaying the transmission. At the bottom of the panel, the amount of bandwidth the remote conference member is using and the number of frames per second that you are receiving are displayed.

Video options

From the Video menu, there are several options you can select involving the viewer panel setup.

Load—Loads your default settings from disk

Save—Saves the current settings as the default

Factory—Restores the Viewer settings to the values set by the manufacturer

Note that the Load, Save and Factory options affect only the current viewer panel.

Freeze

The Freeze option allows you to pause the video transmission. Selecting Freeze again will unfreeze the video. Note that Freezing the video does not actually suspend transmission, it just freezes that frame on your Viewer panel.

Copy

The Copy option moves an image of the current frame to the OpenDVE clipboard, where it can be viewed using the Graphics Tool, or it can be used by other applications. When you copy a frame to the OpenDVE Clipboard, it will replace whatever image is currently stored there.

Settings

The following options under the Settings menu allow you to customize your Viewer.

Color Usage—This setting is only used if you have enabled the Suppress Flashing setting. It controls the number of colors used by the Viewer from the default color map. Changing this setting to high will improve image quality, but will leave fewer colors available for other applications to use. If your other applications have difficulty obtaining colors that they need, reduce this setting to low.

Suppress Flashing—This option prevents color flashing when you move the mouse out of the Viewer panel. The Viewer panel always uses a private color map when it is active in order to produce the best possible image. If this setting is enabled, the Viewer will fit itself into the default color map any time you move the mouse out of the Viewer panel. If this setting is disabled, the Viewer panel will not appear with the correct colors when the mouse is moved from the panel.

Zoom—The Zoom setting allows you to double the size of the Viewer panel. The Zoom function magnifies the image being received, and does not affect the video being sent by the conference member. Since Zoom uses a magnification technique, Zoomed windows will appear slightly less clear than normal ones.

Keep on Top—Enabling the Keep on Top setting will ensure that other panels do not cover the Viewer panel, no matter which panel is currently active.

Some or all of these options will be available to you, depending on the type of video board you have. Other options include visual controls such as hue, brightness, and saturation. If available, these can also be adjusted to improve picture quality.

SGI machines have a Settings panel provided with the VINO video board. Information on the available settings can be found in the system documentation provided by SGI.

Understanding Basic TV Controls

Video Board

This drop-down selection box allows you to select which video capture card you will use if more than one is defined for your system.

Compression

With this drop-down selection box you select codec, video compression-decompression algorithm, that the video you send will use. Supported video codecs include:

Different algorithms have distinct advantages and disadvantages. For example, JPEG compression provides excellent picture quality but is very process intensive, often involving specialized hardware, and JPEG encoding is not supported on all platforms. The CellB algorithm encodes and decodes video quickly and efficiently on all platforms. However, CellB consumes greater network resources than JPEG for any given picture quality.

As all cards do not support all compression algorithms, the specific video capture card you use determines which codecs are available to you. Only algorithms that you can use will appear in the list.

Sending Size

The TV Tool supports three different frame sizes:

The frame size that you select determines the size of the video you broadcast to the conference. The smaller the frame size you choose, the less network resources your video will consume.

For Hewlett-Packard’s DVC Quarter and Sixteenth sizes are defined as resolutions of 352x240 pixels (Common Intermediate Format or CIF) and 176x120 pixels (Quarter Common Intermediate Format or QCIF), respectively.

Full size video is not supported by Hewlett-Packard’s DVC or Sun Microsystem’s Sun Video card.

Frame Rate

This slider regulates the number of video frames the TV Tool attempts to transmit every second.

Drag the slider to the left to lower the number of frames per second sent and to the right to increase frame rate. Alternatively, you can click to either side of the slider control to increase or decrease the frame rate by 10. You can also type a value directly into the Frame Rate field. The minimum frame rate is 1 and the maximum is 30.

Start

When you click on the Start button, the TV Tool begins capturing video and sending it to the conference. After a few moments, all conference participants will see your video with the exception of those members who are unable to decompress your video stream—for lack of the correct decompression algorithm—and those you have chose not to send video to.

Starting the TV Tool’s capture and send process will also bring up a Local Monitor if that feature is present and enabled for your particular video card.

The commands for the local monitor should be the same as those for the remote Viewer panel.

The Start button is only enabled when you are participating in a conference. Further, you may not start while the Video Tool is using the same capture board.

Stop

When you click on the Stop button, you stop capturing video and sending it to other conference members. All remote viewers displaying your video will close, and the Local Monitor, if present, also exits.

This button is only enabled when you are currently sending video.

Pause

A click on the Pause button temporarily freezes the video you are sending to the conference on the current frame. When Pause is selected, the button will be labeled Resume, and you can click on it again to continue sending video to other members.

Advanced TV Controls

Further controls allow hardware specific video adjustment and monitoring, selection of members whose video you will receive and who you will send to, choice of network transport, and limitations on bandwidth consumption. These features are available from the Options menu. Each menu item is associated with a dialog window from which you may perform certain actions. More information about each is provided later in this chapter.

Video—make adjustments specific to your selected Video Board

Members—choose which users you will offer video to and you will accept video from

Network—select a network transport mechanism for your video and limit the network resources consumed by video; additionally, monitor video characteristics of speed and bit rate

Preferences—change the default behavior of the TV Tool

Local Monitor—bring up a viewer displaying the signal you are broadcasting to the conference

The Local Monitor is not available for all video capture cards.

Conference Video

Changing Startup Behavior with Preferences

The Preferences dialog allows you to change the behavior of the video tool regarding transmission and reception of video. The Preferences dialog allows you to set your defaults to accept video from everybody or nobody. Also you can toggle whether Auto Start is on or off. Note that the settings of the Offer Video To and Accept Video From indicate default behavior; their settings are overridden by the Members dialog.

Offer Video To

Your Offer Video To setting determines whether you send video to other members when they join the conference and you are sending video. Selecting Everybody indicates that while you are sending video, when a new conference member is added you will start sending them video. Selecting Nobody means that you will have to select the specific conference members that you wish to send video to using the Members dialog, found on the Options menu.

Accept Video From

Your Accept Video From setting tells the TV Tool whether or not to accept video when it is offered to you. When Everyone is selected, you will receive, by default, any video stream that is offered by another conference member to you. If Nobody is selected and you want to receive video from another conference member, you will have to select them specifically on the Members dialog.

Auto Start

The Auto Start setting indicates whether you will automatically begin sending video to everyone who will accept it when you join a conference. When this setting is on, if you are included in a new conference or you are added to an existing conference, you will begin sending video to everyone else in the conference (unless you have Offer Video to Nobody set). If this setting is Off, you will have to manually start video when you join a conference, if you wish to send it.

Members

Using the Members dialog, you can specify which conference members you will accept video from and offer video to.

The Members dialog box contains two lists of conference participants: those members eligible to receive your video and those members offering you video. The highlighted members in the lists are those users who, in the case of the Offer Video To list, will receive video from you, and in the case of the Accept Video From list, you will accept video from.

To select the users to whom you want to send video:

1. Launch the Members dialog from the Options menu on the TV Tool’s control panel.

2. Highlight only those members to whom you want to send video.

Two shortcuts for selecting members are the Everybody and Nobody buttons. They respectively select or deselect all conference participants in the list.

3. Click the Apply button to implement the change.

You could also click the OK button to confirm your choices, but this also dismisses the Members dialog box. With the Members dialog still open, you can also select those whose video you wish to accept by highlighting their names in the "Accept Video From" list.

To select users from whom you want to accept video:

1. Highlight the names of the users that you wish to accept video from.

The Everybody and Nobody buttons also work on the Accept Video From list, selecting and deselecting the entire list of conference members.

2. Click OK.

Once the OK button is clicked, any changes will take effect and the dialog box will be dismissed.

Networking

Preferred Transport

The TV Tool supports multicast UDP and unicast UDP network transport. This field indicates which network transport protocol is used by the TV Tool. Your network transport protocol is set internally by a Communique! initialization file. For details on changing it, consult the Communique! Administrator’s Guide.

Unicast is the traditional IP transport protocol. Under Unicast, one stream of data is sent over the network to every user who is receiving your video. For example, under Unicast, a person sending one packet of video data to five other conference members will send out five separate packets, one to each individual user.

Multicast, on the other hand, sends only one stream of data, which is automatically received by every user it is intended for. In multipoint conferences, multicast greatly reduces the amount of network resources used by video, and decreases the workload of the sending machine. If multicast is selected as your Preferred Transport, Communique! will still automatically detect which users are using unicast and automatically send them an individual stream.

Multicast Range

Multicast Range is an attribute of Multicast routing that defines how far a multicast packet travels through across the network. Each time a multicast packet travels through a network gateway, its TTL value is decremented. Although there are no set standards for Multicast Range, there are a few conventions that have been established:

1 Restrict the packets to the local subnet

32 Restrict the packets to the site

64 Restrict the packets to the region

128 Restrict the packet to the continent

256 Do not restrict the packet’s travel at all

You should have the Multicast Range set to the lowest amount required. Multicast Range is set internally by a Communique! initialization file. For information on changing it consult the Communique! Administrator’s Guide.

If you are using Multicast UDP as your video transport mechanism and a conference member’s host station operates further away (across more gateways) than the Multicast Range setting allows, that conference member will not receive your video. You can increase your TTL setting so that they will receive it, however.

Bandwidth

The Bandwidth setting can be used to set a hard ceiling on the amount of network resources that the TV Tool can use. Communique! throttles the video you send in order to prevent it form using more than the prescribed amount of Kbps (Kilobits per second).

If throughput is not a concern, you can select Unlimited, which allows the TV Tool to use as much bandwidth as necessary to achieve the other settings that you have selected. Additionally, you can select Unlimited and manually regulate the amount of bandwidth used by adjusting your Frame Size, Frame Rate and Quality settings.

In OpenLook, when you enter a maximum Bandwidth setting the Quality and Speed sliders will no longer have any effect on your video.

Favor

With an imposed Bandwidth restriction, the TV Tool must often choose between image quality or frame rate in the video it sends. With the Favor drop-down selection box, you can weight the tool’s choice to your preference or need. When you are favoring Speed, The TV Tool will attempt to reduce bandwidth consumption by reducing your Quality setting. Likewise, favoring Quality will result in reduced frames per second in order to work under the bandwidth cap.

Data Sent

Data Being Sent informs you of how much network bandwidth the video you are sending consumes, measured in Kilobits per second.

Frame Speed

Frame Speed displays the number of frames per second that you are currently transmitting.

Configuring Video Board Specific Controls

Communique! supports a large number of video capture cards, all with different features and settings. However, most of the board specific settings can be categorized as follows:

The Video Board specific controls are available from a dialog box opened by choosing Video from the Options menu. This screen shot is a picture of the Video Options for Parallax users:

Connections

Most video capture cards have a number of input connections. This number can vary from device to device. If a video capture card supports more than a single input port, the TV Tool provides a drop-down selection box in the Video dialog which allows you to specify which port your video is connected to.

Signal Formats

Some video capture cards support a number of different signal formats that they can accept from a video source. Some supported signal formats are:

Your video capture card may not support all of these signal formats.

Quality Scale

If your video capturing device supports JPEG or CellB encoding, the TV Tool also provides a Quality slider in the Video dialog for adjusting the image compression. The slider ranges from 0, which provides the highest compression but the lowest quality, to 100, which provides the highest image quality but is virtually uncompressed.

Picture Adjustments

Boards supporting CellB or JPEG compression algorithms also have picture adjustment controls available when using those codecs. Brightness, Contrast, Saturation, and Hue correspond to standard television controls of the same name, and they affect the same image characteristics such as brightness and color.

These controls are sliders, with minimum values of 0 and maximum values of 255.

Hewlett Packard DVC Specific Controls

Gamma Correction
Gamma Correction compensates for differences in the way video equipment interprets color data. If the color of your video does not appear to be correct, toggle the Gamma Correction switch.

Auto White Balance
If you are using a digital camera, Auto White Balance can be used to correct color imbalances. If the colors are not correct, you should follow these steps:

1. Stop capturing video

2. Select the Auto White Balance button

3. Hold a piece of white paper in front of the camera

4. Start capturing video

5. Deselect the Auto White Balance button

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