OpalVOIP is an open-source library for developers creating voice, video and fax applications over IP networks. It includes H.323, SIP and IAX2 protocol stacks, a low-latency RTP stack, audio codecs such as G.711 and Speex, and video codecs including H.261 and H.263. A loadable codec interface allows applications to add further implementations.
| Author: | Craig Southeren and Robert Jongbloed |
| License: | Open Source |
| Price: | FREE |
| Released: | May 12, 2016 |
| File size: | 6.20 MB |
| Downloads: | 325 |
| Keywords: | phone library, rtp multimedia library, fax library, voip, h323 library, OpalVoip, VoIP technology, x64 software, Windows 10, Craig Southeren, fax, ip fax library, voip development library, phone, opalvoip library, voip library, Opal Voip, Robert Jongbloed, sip protocol stack, OpalVOIP |
| Author URL: | http://www.opalvoip.org/ |
OpalVOIP is an open-source communications library for developers building software that sends voice, video and fax over IP networks. Rather than acting as a ready-made calling application, it supplies protocol and media components that can be integrated into phone systems, conferencing tools, softphones and other networked communications software. It grew out of the OpenH323 project and supports several established approaches to internet telephony.
The library provides H.323, SIP and IAX2 protocol stacks for setting up and managing calls. Applications can use these protocols to communicate with compatible endpoints and services, while OPAL handles the underlying signaling and media exchange. Its RTP stack is designed for low-latency real-time multimedia, helping developers carry live audio and video with less delay than general-purpose data transfer would allow. Fax transmission over IP is also part of its scope.
For audio, OPAL includes codecs such as G.711, GSM 06.10, Speex and iLBC. Video codec support includes H.261 and H.263. A runtime-loadable codec interface lets an application add other implementations, including proprietary codecs or options such as G.729, H.264 and MPEG-4, where appropriate licenses and components are available. This modular approach helps developers tailor media support to the devices and services their software must work with.
OPAL is intended for integration into larger software projects, so its practical value lies in the communications features it provides rather than a standalone user interface. Developers can use it as a foundation for IP telephony, audio or video calling, conferencing, and fax applications. The PTLIB platform isolation library supports deployment across different system architectures, from embedded devices to multiprocessor servers, and helps keep platform-specific details separate from communications logic.
The project is open source and uses the Mozilla Public License. OPAL has been developed for Windows as well as Linux, macOS, BSD, Solaris and Windows Mobile; the Windows download is aimed at developers working with compatible Windows systems. It is a technical library, so using it generally requires programming experience and an application that incorporates its components. Codec availability and licensing can vary, particularly for proprietary formats.