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AV conferencing

Audio conferencing[top]

Making audio conference is relatively cheap and easy. All you need is 1) an audio card (preferrably full duplex - meaning that it can both record and playback at the same time), 2) a not-so-fast PC running some flavor of 3) Linux or BSD (do not forget we are talking about the cheapest way) and 4) internet connection. Once you get these, you can start talking to your friends almost right away.

Next step is getting the necessary software. Some of you might think downloading the Yahoo! or MSN Messenger is good enough for them, and well, they might be right. However, I prefer using programs that comply with some well defined protocol. Using a program like that would most certainly let you talk to any user using any other program that supports the protocol in question. Using one of the messengers above will only let you speak to users with those messengers. You probably get where I am hinting by now. I am talking about the H.323 protocol. It is in fact what both Yahoo and MS use in their VoIP implemention, with the only difference that they did not care make it in such a way that it would be possible to talk to standard H.323 software.

What you can do in this case is go to OpenH323 and get your copy of their libraries. You can also get the source code and compile them yourself. I do not know how easy the compiling process on Windows is, but I am sure it is not cheap - you need the MS Visual Studio. On Linux it is as easy as easy could get, and BSD should not be much different.

After making sure you have your own copy of PWLib and OpenH323 you would have to choose one of the variety of software that uses those libraries. If you run Windows you could use OhPhone or OpenPhone downloadable from the same location as the libraries. You can of course use NetMeeting if you can make your way through the mystery of its interface, and if you do not mind being unable to make calls from behind a NAT router (or Internet Connection Sharing as Microsoft likes to translate it). For Linux/BSD you can choose between OhPhone, GnomeMeeting (a program with a pretty GUI) and CPhone, which also works on Windows by the way. It would be nice to look at the Contributors page on for info on H.323 compatible software.

Well you are all set. Fire up your favorite program and start blabbering.

Video conferencing[top]

Video conferencing means that you also need a so-called webcam if you run Windows, though for Linux you would have to make sure the webcam is supported by the video4linux project (google is your friend; just search for v4l along with your webcam model). However, if you own a fancy digital camera that has a IEEE1394 interface (also called FireWire or i.Link) you are in luck - you can use it instead.

Once you get that - make sure you load all the necessary drivers/modules, make sure you tell your favorite program to use your camera as a videodevice, make sure you enable the transmission of video in the program (sometimes disabled per default) and you should have no other problems. You are all set to join a conversation "in person".

Using a IEEE1394 camera for video conferencing[top]

This section is pretty outdated. The patches that it talks about have been integrated in the original projects

Yes it is now possible to use a Firewire camera for videoconferencing if you use the OpenH323 libraries and you run Linux/BSD. First you would have to identify what kind of camera you have. The two kinds are DC and AV/C cameras. If it is a video camera you can be sure it is an AV/C camera. If it is a DC camera you have to recompile your PWLib setting the environment variable TRY_1394DC to something. You would also have to compile OhPhone/GnomeMeeting in a similar manner and I do not know of any other programs supporting them (actually GnomeMeeting still does not but keep reading).

If yours is a digital video camera, then we get to the point why I started this whole page. I just added support for AV/C cameras to PWLib. You can get my patches here. Copy the video4avc1394.cxx file where video4dc1394.cxx is (should be in $PWLIBDIR/src/ptlib/unix ) and videoio1394avc.h should go in $PWLIBDIR/include/ptlib. Apply the pwlib.diff patch like this:patch -p 0 -d $PWLIBDIR < pwlib.diffthen set the environment variable TRY_1394AVC to something and compile away.

No matter what program you decide to use, you will certainly need to recompile it, too. Patches for OhPhone and GnomeMeeting can also be found. OhPhone should be compiled by setting TRY_1394AVC and for GnomeMeeting you have to do that, and also use make CXXFLAGS=-DTRY_1394AVC when compiling instead of just make. My patch to GnomeMeeting also includes a patch from Bob Mroczka that adds DC camera support. You only have to substitude TRY_1394AVC with TRY_1394DC and you are good to go.

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