In today's global economy, videoconferencing continues to grow in popularity. However, conference participants in several locations formerly needed the same type of equipment to communicate.
To solve this problem, VideoServer, Inc., has created the standards-based Multimedia Conferencing Server (MCS) to utilize recently developed videoconferencing standards that accept communications from various equipment. To design and develop these systems, VideoServer uses the processing capabilities of TMS320 DSPs and the object-oriented programming capabilities of C++, from Tartan, Inc.
VideoServer units now on the market handle video and audio. They were developed in accordance with H.320, which covers such functions as procedures for establishing communication, video frame structure, synchronous control, audio encoding, and confidentiality.
Standard T.120, or multipoint data sharing, will incorporate data conferencing to the video and audio portions. This will allow users to not only see and hear the other participants, they can also share access to software programs, such as a spreadsheet.
VideoServer is already crafting this new functionality as the standard emerges. Much of the MCS software is written in C, but T.120 provides several reasons for moving to C++ says Chuck Grandgent, VideoServer's Manager of Multimedia Research. "T.120 encourages object-oriented programming, and C++ lets us hide the different protocols used by different conferences or users. It also provides class libraries to easily implement resource tokens, mandated by the standards."
The DSP boards used by VideoServer are based on TMS320C31 processors, usually nine to a board. Together, they unpack, format, and repack the audio, video, and data, and send it out as a unit. The 'C31 is used because it possesses the required computational horsepower to perform this compression, as well as run the conference. "The trick is to compress the information so that it will fit on inexpensive transmission media," says Grandgent, "unlike the large and expensive satellite bandwidth that brings you Dan Rather from Moscow."
Portability is another reason for moving to C++, as the 'C31 boards are part of a PC-based system. The code must run on both the DSPs, which handle the communication, and the PCs, which handle other system tasks. Code is often developed in the self-hosted PC environment and moved to the 'C31.
