CU-SeeMe Operation


Launching Out

Before you launch CU-SeeMe, make sure your screen is set to a resolution that includes 16 gray scale with the Monitors control panel. Settings that will work are: 16 grays, 256 grays, 256 colors, thousands of colors, millions of colors. On AV Macintoshes, you need to reduce resolution to be able to digitize and send video.

NOTE: Setting preferences: Make sure that you type your own name in the preferences setting, so that "YOUR NAME" does not appear when you broadcast

The settings you make are stored in a document in the Preferences Folder. You may change these settings with the Preferences... item on the Edit menu.

When the program opens, if a video window on the top left of the screen appears, the program believes you have a digitizer installed with the Quicktime extension and the necessary VDIG component--or that you have an AV-Mac.


By default, a button bar appears below each video window and a rates bar below the button bar shows statistics on framerate and bandwidth used. You can get rid of all button bars with a checkbox in the Preferences... dialog.


If you have a send-equipped Mac running the program, waiting for a request to send, the bar under the local window will show *WAITING* until someone connects to you or you connect to someone. The framerate indicator shows the speed of framegrabbing, which depends on the resolution you choose and the cpu power available, and possibly on the screendepth set with the Monitors control panel. It will be highest on a fast machine, running in the foreground, capturing the small size ("Standard" resolution) with the screen set to 16 grays. If you choose to mirror the image, have part of it off the screen or covered by another window, the rate will be slower. With buttons in the local window button bar, you can mirror the image (makes it easier to position), "pause" sending, or bring up sets of controls to adjust transmission, compression, brightness and contrast, audio parameters, and choose a digitizer if you have more than one.


For a two-party conference, choose Connect from the Connection menu. Type in an IP address of a digitizer equipped Mac running CU-SeeMe 0.80, 0.70 or 0.60 (Earlier versions are NOT compatible) or a current Windows version on a PC. For a multiparty conference, enter the IP address of a reflector. (See "How to Test CU-SeeMe following this section.) If all is well, and no one else is already connected to the Mac you designated, it will start sending an image to you. If you are calling a reflector, you may be the only one connected, in which case you will see no windows until someone else connects. If the reflector does not respond immediately, the rates bar will show *CONNECTING*. If there is no answer, you'll get a "no response" message. Note that when you disconnect, the program will ignore any packets received from the same address for 60 seconds. This should not present any problems with reflector connections, but if you are taking turns connecting and disconnecting point-point, there would be some possibility of confusion. However, the 60 second delay applys only one way-- that is, if you disconnect, you can reconnect to the same address right away, but that address can't connect to you for 60 seconds.


As an alternative to repeatedly typing in IP addresses, you may use Edit Nicknames from the Edit menu to set up Nicknames for IP addresses. Then use Connect To > from the Connection menu to make connections. DNS names are now supported in the connect dialog, but not yet in the Nickname file. A further release will have support for url format nicknames and saving bookmark files containing a url which will launch CU-SeeMe and connect to the site pointed to by the url. Apple events will also work for launching/connecting, so it should be possible to set up web brousers to establish CU-SeeMe sessions. But we havn't had time to wring this stuff out for this release.

RATES BAR When someone requests a connection (or you open a connection) and you start sending--you will also see, in addition to framerate, an indication of bandwidth in Kbits/sec. On the right end of the rates bar under the local window is shown a "cap" which limits bandwidth used for sending and hence framerate, depending on amount of motion. The minimum and maximum values for the cap can be adjusted by a control in the Transmission panel (use the rightmost button in the button bar and choose Transmission from the popup menu. If the receivers report packet loss in excess of 5%, the program assumes network congestion and automatically lowers the cap. It will be adjusted back up toward the max value if loss reports agregate to less than 5%. Note that this system does not work well if a conference mixes receivers on paths with greatly different bandwidths available. A future release will address this issue.


You can start and stop sending or receiving on the fly (on the Conference Menu), without disconnecting and reconnecting. You may wish to "drop in" on a conference in receive-only mode, to see who's there, and then start sending when you see you would not be over-burdening the conference. You can also use the "pause" button-- it's use will stop the capturing of new frames, effectively freezing the video. Video will continue to be sent on the aging timer at a very low rate. Use of the pause feature is preferable to leaving an active camera on an empty room. If you want a message to be displayed, type it before pausing.


The Participants menu gives the means for opening particpant windows if they have been closed. It shows names of conference participants and their status. The local window is listed first, followed by conference senders, followed by receive-only participants ("lurkers"). Presently, you can have up to 7 remote windows plus the local window for a total of 8. Up to 16 participants will be listed on the menu. When a participant disconnects from a conference, the rates bar will show *DISCONNECTED* or, if no packets are received for a while, it will show *TIMED OUT*. If it shows no motion and very low framerate and bandwidth, it has probably been "paused."


Each time a remote video window opens or is resized (or you connect to "self" for testing) , a middle-gray field appears followed by an impromptu demo of the frame differencing and aging algorithms. The main compression in CU-SeeMe is achieved by comparing successive captured video frames and sending only the parts that change. Only changed 8x8 pixel squares are sent, except that if a square remains unchanged for a number of frames, it is sent anyway to heal image artifacts resulting from lost packets. Initially, the "age" of each square within the Refresh Interval is set to a random number, so the window will fill in gradually or as the subject moves. You can adjust the Refresh Interval in the Transmission panel.


CU-SeeMe windows presently come in two sizes; 160x120 and 320x240. By default, the smaller size frames are grabbed and displayed. You can choose the larger window size in the Compression panel. (Caution: frame grabbers are generally much faster at producing the smaller windows.) Whichever size you transmit, you can display at either size. You can also display remote windows at either size. If you are getting the small size and displaying the large, three quarters of the pixels are generated by simple linear interpolation. (It's amazing it works as well as it does.) Using the zoom box (upper right in title bar) on the window will allow you to toggle quickly between large and small window sizes.


On the File menu is an item you can use to save current window positions. Until you use it, they open tiling left to right. You probably want to move them around while you remember the order they came up and then save. The Participants menu lists the order that windows open as you initially connect to a reflector. You can go back to defaults by chucking your preferences file. This facility will be improved to make it easier to get the results you want.


You can set a preference for the maximum number of windows you want to show at one time (default 8, set between 2 and 8), including your local window. This feature will help if you have limited screen real-estate.


By default with Version 0.80, windows will not open when you connect to the reflector or when new participants join a conference. Especially if you are connected with a low-bandwidth link, such as a modem, you should not choose to automatically open windows. With another new preferences item, you can choose to hear a click each time someone joins a conference.


The VDIG for the Spigot board maintains a fifo (first in first out) of frames, several frames deep, so each frame grabbed is three or four frames old. Each time the program grabs a frame, the VDIG gets another one and puts it at the far end of the fifo cue. When running at 30 fps, a 3-frame delay is not a big problem, but at 10 or fewer fps, the delay becomes significant in terms of lip-sync with telephone audio. The AV Mac's do much better at minimizing delay, but the Spigot generally runs faster. Also, the Spigot doesn't produce as good an image in the SlideWindow (and the Quickcam won't produce a 640x480 image at all).


The Message Crawl feature allows banner messages to appear and scroll on the screen. Simply type (with CU-SeeMe in the foreground), and the characters you type will be displayed at the bottom of your local video window and transmitted with your video. (Note that if you mirror your local image, you will have to read backwards as you type! But remote viewers will see it correctly.) This admittedly "cute" feature is actually useful for brief messages like "Call me. 515-222-3333." If you type the up-arrow, you can move the line to the top of the screen; down-arrow puts it back at the bottom. Left-arrow will animate the text, starting it scrolling to the left. A second left-arrow will speed it up. Right-arrow reverses the effect (slows or stops the crawl). Please remember that a scrolling message creates more movement eating up bandwidth. BE KIND TO THE INTERNET and other CU-SeeMe senders and receivers. Use scrolling sparingly; e.g., don't go away and leave a picture up with a message scrolling.


Buttons on the button bar on remote windows will bring up a stats panel or an info panel. The Stats panel shows amount of data sent and received and loss rates, both as measured locally for data received and what the other end is reporting. Info currently shows just the IP address and the version of CU-SeeMe in use remotely, stay tuned, here is where location, phone number, etc. will be displayed.


Audio code for CU-SeeMe is based on the Maven code, provided by Charlie Kline of UIUC. Audio is controlled from a small window and works just like Maven. You can choose Push-To-Talk mode (PTT) or set a squelch level with a small pointer to the left of the audio-level bar. You know audio is going out when the icon below the VU-meter is high-lighted and you get a good indication with the VU-meter. Try for about a 75% VU indication, but not more or you may get distortion. There are boxes in the audio window to turn receive and send on and off entirely. Or you can turn off audio from a particular particpant by pushing the speaker button under their video window (at their end, they will get the mic on your window X'd to indicate you won't hear when they speak). When you have incoming audio, the speaker button highlights under the speaker's window.

Also, you can choose to turn off receiving from standalone Maven (or VAT) clients who connect to the reflector (a temporary hack until we have a list-window for participants not displaying video).

If you push the mic button on someone's window, you establish a private talk channel to them. The mic buttons on all the other windows get X's to indicate that those participants won't hear you when you talk. Push again to go back to general conference audio sending.

This should work much better with low bandwidth links, such as 64K ISDN links, and possibly with 28.8K modem connections. However, compared to the DVI 32K encoding, assuming no packets lost in either case, the sound quality is noticibly poorer, although speech is entirely intelligible. You will not be able to use this encoding to converse with anyone using an earlier version of CU-SeeMe. You will not be able to interoperate with VAT. You should be able to use it with recent versions of Maven.

BUT. ***Now Hear This*** (and tell your friends): AUDIO WILL NOT WORK CONNECTING WITH A 14.4 MODEM!!!

I know it would be great if it did, but it just doesn't. You need at least 16K bits/sec plus overhead just for the audio (when speaking or listening) and a 14.4 modem only does 14.4K. (Don't expect much gain, if any, from the v.42 compression, since the audio is already quite tightly encoded.) If you have 28.8, and folks are sending with the 16K delta-mod, there is a chance. We will be working to improve this situation in the future, but you probably won't see low-bw audio for other than PowerMac's or pretty hot PC's.


The Conference menu includes an item to open the Audio Window (if you've closed it) and an item to open the SlideWindow. In future, there will be more conference-management related items on this menu. Of course, as time goes by, we may need to re-organize the menus to make sense of future developments which aren't even gleams in the eye today.


Also on remote window button bars is an eye-con (sorry, couldn't resist). If open, it means that the person in the window is looking at you-- or actually that they have a window open on their desktop showing your video stream. (But it may be covered by another window.) If they close the window, the eye at your end closes. When the eye is open, it looks a little sinistre, some folks think. Icons are still being edited.


If part of the video portion of a CU-SeeMe window is covered, the program uses QuickDraw to move video into the window. Otherwise, optimized routines draw directly to the screen. Particularly on a slower Mac, drawing with QuickDraw is very slow. So you will know when this is happening, a black border shows on such a window. There is a preference item to disable direct screen drawing, and omit black borders if direct screen drawing is disabled. For those doing demo's with powerbooks and projectors, wanting to run in Mirror mode, this choice should allow the desired operation.


The Connection dialog has a box for conference ID, default of zero. The reflector will reject all participants with the wrong number unless it has been configured with a conference ID of zero, meaning "don't care." If you have been told to use a particular ID, you can connect to a reflector.

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