BigSpeed Voice Chat SDK Version 1 descriptions BigSpeed Voice Chat SDK is a set of two ActiveX controls that lets you set up a private voice chat network for secure messaging. The transfered data are scrambled using on-the-fly 128-bit AES encryption. The security is provided in two different modes: symmetric encryption with shared secret key & asymmetric encryption with 1024-bit public/private keys. The server is responsible for keeping information on & authentication of online peers. All peers connected to a particular server build a single private community. Fine grained access control is realized by a group of user-oriented permissions. They grant access control privileges to system resources & services in a flexible & secure manner. The voice stream is highly compressed to deliver the best possible sound over a limited-bandwidth connection. In addition the average bitrate is reduced thanks to the silence compression. In the encoder a voice activity detector with an adjustable trigger level is used to distinguish between regions with normal speech activity & those with silence or background noise. Significant echo suppression is achieved using a robust double talk detector. Capability to mute recording & mute playback is implemented. The incoming & outgoing audio data are available in raw PCM format for visualization in the application. Two special events notify about signal overloading & transmission delays . Two different kind of text information can be exchanged between peers: alert & chat messages. File transfer capability is implemented for direct file exchange between peers. BigSpeed Voice Chat SDK utilizes an elegant event-driven paradigm for easy integration into Windows applications. A special attention is paid to provide responsive user interface while avoiding multithreading problems. Sample applications are included in Visual Basic 2005 & Delphi 7.