Microsoft® NetMeeting™ 2.1 ships with four ITU (International Telecommunications Union) standard codecs: G.711, G.723, H.261, and H.263. For streaming audio and video, there is a tight coupling between a codec and its RTP payload handler. RTP is the network transport protocol that NetMeeting uses for audio and video streams. An RTP payload handler organizes audio streams into packets for use by the RTP. RTP is not yet a part of the Microsoft Windows® operating system. Windows has a general-purpose means for installing and using codecs, namely ACM and VCM (VCM is also known as ICM). But Windows has no general-purpose means for installing RTP payload handlers.
NetMeeting supports the H.323 standard, which calls for the use of RTP and the four standard codecs mentioned above. To get optimal performance and a quality end-user experience, NetMeeting 2.1 has gone beyond the limitations of the interfaces defined in ACM and VCM by linking the NetMeeting implementations of the standard codecs with specific RTP payload handlers built to use these implementations with the RTP and call control components in NetMeeting.
Last Updated: November 1, 1997
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