3. Events

This chapter provides information on events that may be returned by the Continuous Speech Processing (CSP) software.

An event indicates that a specific activity has occurred on a channel. The voice driver reports channel activity to the application program in the form of events, which allows the program to identify and respond to a specific occurrence on a channel. Events provide feedback on the progress and completion of functions and indicate the occurrence of other channel activities. Events are sometimes referred to in general as termination events, because most of them indicate the end of an operation.

The following events, listed in alphabetical order, may be returned by the CSP software. Use sr_waitevt( ), sr_enbhdlr( ) or other SRL functions to collect an event code, depending on the programming model in use. For more information, see the Standard Runtime Library Programmer's Guide (in theVoice Software Reference).

TDX_BARGEIN

• Termination event. Indicates that play was terminated by the VAD due to barge-in. Barge-in is enabled using the DXCH_BARGEIN parameter in ec_setparm( ).

TEC_CONVERGED

• Termination event. Occurs when the echo canceller sends a message to the host application that the incoming signal has been echo-cancelled (converged). Echo-cancelled convergence notification is enabled using the DM_CONVERGED parameter in dx_setevtmask( ).

TDX_CST

• Unsolicited event. Indicates a firmware buffer overrun when the event appears with the REC_BUF_OVERFLOW subcode. To retrieve the DX_CST structure and this code, use sr_getevtdatap( ).

TDX_PLAY

• Termination event. Can optionally be received (in addition to TDX_BARGEIN) to indicate that play was terminated by the VAD. Specify using DXCH_BARGEINONLY parameter in ec_setparm( ).

  Note: When the VAD is not enabled, the TDX_PLAY event indicates termination for dx_play( ) in asynchronous mode. For more information, see the Voice Software Reference.

TEC_STREAM

• Termination event. Indicates that an echo-cancelled record function, ec_reciottdata( ), or echo-cancelled stream function, ec_stream( ), has ended.

TEC_VAD

• Termination event. Occurs when the voice activity detector (VAD) sends a message to the host application that significant speech energy has been detected. VAD event notification is enabled using the DM_VADEVTS parameter in dx_setevtmask( ). This event is only generated when data is being recorded or streamed.

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