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The OpenH323 FAQ
Version 1.5, 19 November 1999 |
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The latest version of this document can always be found at: http://openh323.org/faq.html Contents:Section 1 - Introduction Section 2 - The Source Code Section 3 - Codecs, applications, and hardware Section 4 - Standards and documentation Section 5 - How to contribute Section 6 - Mailing list Section 7 - Miscellaneous SECTION 1 - Introduction1.1 What is the OpenH323 project? OpenH323 is a project committed to the collaborative development of an Open Source H.323 protocol stack that is available for use by both private and commercial users. It was started in September 1998 by Equivalence Pty Ltd, a private company based in Australia 1.2 What is the H.323 protocol? H.323 is the name given to a set of communications protocol is used by programs such as Microsoft NetMeeting to transmit audio and video information over the Internet. It was developed by the ITU (http://www.itu.org) 1.3 Why is the OpenH323 project needed? OpenH323 is needed because commercial implementations of the H.323 protocol stack are expensive to license and distribute. They also contain proprietary IP that cannot be used or distributed without the permission of the owners, and they are not Open Source. If normal users and small companies are to create products and services that require the use of the H.323 protocol, then an unencumbered implementation needs to be available for these users. 1.4 Where can I find OpenH323? The OpenH323 web site and mirrors are located at: http://openh323.org 1.5 What license is OpenH323 is covered by? OpenH323 is covered by the Mozilla Public License. This is basically the same as the LGPL. The terms of the license allow you to use the source code for any purpose at no cost, as long as you make any changes to the source code freely available under the same licence as OpenH323. 1.6 Can I use OpenH323 in a commercial product? Yes, as long as you conform to the terms of the license. The source code to your product does not have to be Open Source (unless it contains fragments of code from OpenH323), but any changes you make to OpenH323 must be made available under the same license as OpenH323. 1.7 What license fees do I have to pay for using OpenH323? No fees are payable for using OpenH323, although donations are gladly accepted! 1.8 Where can I find more information on Open Source? More information on the Open Source concept can be found at http://www.opensource.org 1.9 Why isn't OpenH323 available under the GPL or LGPL? We feel that the MPL allows the maximum amount of flexibility for both users and developers. The GPL is too restrictive in what can and can't be done, and the LGPL is too ambiguous to be safely used. We chose the MPL license specifically because it allows developers to use proprietary, closed source code with OpenH323 without being compelled to release their own code under the same license. Both the GPL and LGPL do not allow this. Also, the LGPL is not suitable as it cannot be guaranteed that it will not be necessary to add non-GPL code modules to OpenH323 that are not in library form. We are not able to release OpenH323 under both the MPL and GPL, as this would require obtaining the permission of all of the contributors to OpenH323 in order to do so. SECTION 2 - The source code2.1 Why is the code written in C++ ? Because C++ really does make the job easier. Truly. 2.2 What is all of this PWLib stuff? PWLib is a multi-platform code library that can be used to write applications that will compile and run on Windows, Linux and a few other Unix variants. It was developed by Equivalence, and is also Open Source. 2.3 I've downloaded the sources and they don't compile. Why not? Trust us - the sources DO compile. You've most likely missed a step in setting up your system. Check the instructions at http://www.au.openh323.org/build.html again, or check below for some common problems. a) You will need GNU bison (version > 1.25), GNU flex (version > 2.5.4) and GNU make (version > 3.75) to compile OpenH323. If you don't have these commands installed, then it won't work, and you are risking getting flamed if you ask on the mailing list about this problem. The programs are available from your local friendly GNU archive or on your Linux install distribution CD-ROM. Windows users can get them get them from http://openh323.org/bin/flexbison.zip b) On Windows, if you get an error like:
then you have not installed bison and flex, or the directory they are in is not in the PATH environment variable. Fix this and try again c) If you get an error about asn_grammar.cxx or asn_grammar.h not being found, then bison or flex is probably not installed. d) If you get an error about asn_grammar.cxx not being able to be compiled, then you have a damaged bison.simple. See http://openh323.org/bison_bug.html for information on how to fix this problem. e) If your Windows system cannot run the command "asnparser", then you have probably either not built the ASN parser or the pwlib/lib directory g) If you are compiling on Linux, you may get errors like the following: obj_linux_x86_r/main.o: In function `MyH323EndPoint::Initialise(PArgList &)': This problem may occur if you ccompile a version of OpenH323 prior to 1.0alpha2. First try getting the latest sources, and recompiling. If the problem persists, then the Makefile is not recognising your system as a Linux system. The workaround is to set the OSTYPE environment variable to "linux". But let us know if you have this problem, and we'll fix it in the next version 2.4 How do I get the latest version of the OpenH323 source code? The latest fully tested and stable version of the source code will always be available for download from http://openh323.org/code.html. The most recently compiled, but not necessarily stable, version of the source code is automatically created by our autosnapshot system every night and uploaded to http://openh323.org/bin/snapshots. The absolute latest version of the source code is always available from the OpenH323 CVS. Code downloaded from the CVS is not guaranteed to compile or even work - caveat emptor applies. Instructions on accessing the CVS archive can be found at http://www.au.openh323.org/code.html#cvs 2.5 How do use PWLib in some directory other than $(HOME)/pwlib? Firstly, unpack the library in your selected directory. Then set the PWLIBDIR environment variable to the new location. SECTION 3 - Codecs, applications, and hardware3.1 Is there a H.323 client in OpenH323? Yes - the "test" directory contains a simple H.323 endpoint called "voxilla" (for historical reasons). This command line application can initiate, or accept, an H.323 connection. Voxilla is a fully-fledged voice application. We are working on a GUI version called openphone that is also in the OpenH323 CVS. 3.2 Does OpenH323 work with NetMeeting/VideoPhone/random H.323 software X? OpenH323 can interoperate with NetMeeting 2 and NetMeeting 3. If you have any further information on other applications that do (or do not!) work with OpenH323, then please post to the mailing list. 3.3 What hardware and software platforms are supported? OpenH323 is extensively tested on Linux and Win32. It has been compiled on Solaris, FreeBSD, and BeOS. No special hardware is required to use OpenH323. However, the "voxilla" test application requires a full-duplex sound card in order to make audio connections. The voxilla application also supports the QuickNet cards on the Linux platforms. You will need the QuickNet linux kernel module, and a card, to use this support 3.4 What audio codecs are supported? The G.711 and GSM are supported in software. Most other codecs are covered by some sort of patent or legal restriction, and hence cannot be included without paying license fees. The voxilla test application has support for the G.723.1 codec if a QuickNet card is installed. 3.5 What video codecs are supported? The H.261 codec is supported for decoding only. 3.6 Why isn't audio/video codec "x" supported by OpenH323? Probably for one of the following reasons: a) The patent is covered by some sort of legal restriction and can't be used without paying lots of money to someone b) No-one has implemented it yet! SECTION 4 - Standards and documentation4.1 What standards cover H.323? The following standards are all part of the H.323 group: Call signallng and control
Audio codecs
Video codecs
Related standards
4.2 Where can I get copies of these standards? The latest and definitive copies of the specifications can be purchased from http://www.itu.org 4.3 Can you put a copy of the specifications on the web OpenH323 site? In most cases, the final specifications that cover H.323 are copyright and cannot be freely distributed. However, draft copies seem to be freely distributable and, where possible, we will make copies of these available at: http://openh323.org/standards.html SECTION 5 - How to contribute5.1 Getting the code See the code download page at http://openh323.org/code.html 5.2 Compiling the code See the code build instructions at http://openh323.org/build.html 5.3 Submitting changes Just post your changes to the mailing list. We'll pick them up, and add them into the respository 5.4 What can I do to help? Pick something that looks interesting, and start coding! SECTION 6 - Mailing List6.1 How do I subscribe to the OpenH323 mailing list? The OpenH323 mailing list is managed by a majordomo server at the following . To subscribe to the list, send an email addressed to:
with the following text in the body of the message: subscribe openh323 email_address where email_address is your email address. Don't send the command with the string "email_address" - it really looks stupid! 6.2 How do I unsubscribe to the mailing list? To unsubscribe from the list, send an email to the address above with the following text in the body of the message: unsubscribe openh323 email_address 6.3 How do I post a question or reply to the mailing list? To post a message to mailing list, send your message to 6.4 Is there an archive of the mailing list? An archive of the mailing list can be found at http://vserver.equival.net/~majordom/lwgate.cgi/openh323. SECTION 7 - Miscellaneous7.1 What other OpenH323 projects are available? There are several other Open Source projects using the OpenH323 library. A listing can be found here. 7.2 Can I get commercial support for OpenH323? Equivalence is offering commercial support for OpenH323, including per-hour consulting and service contracts.
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