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WM_CAP_SET_CALLBACK_CAPCONTROL
The WM_CAP_SET_CALLBACK_CAPCONTROL message sets a callback function in the
application giving it precise recording control. You can send this message
explicitly or by using the capSetCallbackOnCapControl macro.
WM_CAP_SET_CALLBACK_CAPCONTROL
wParam = (WPARAM) 0;
lParam = (LPARAM) (LPVOID) (fpProc);
Parameters
fpProc
Address of the callback function. Specify NULL for this parameter to disable a
previously installed callback function.
Return Values
Returns TRUE if successful or FALSE if a streaming capture or a single-frame
capture session is in progress.
Remarks
A single callback function is used to give the application precise control
over the moments that streaming capture begins and completes. The capture window
first calls the procedure with nState set to CONTROLCALLBACK_PREROLL after all buffers have been allocated and all
other capture preparations have finished. This gives the application the
ability to preroll video sources, returning from the callback function at the exact
moment recording is to begin. A return value of TRUE from the callback function
continues capture, and a return value of FALSE aborts capture. After capture
begins, this callback function will be called frequently with nState set to CONTROLCALLBACK_CAPTURING to allow the application to end capture by
returning FALSE.
See Also
capSetCallbackOnCapControl
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