Your application can register callback functions with a capture window to have it notify your application when the status changes, when errors occur, when video frame and audio buffers become available, and to yield during streaming capture. The following messages set the callback function.
| Message | Description |
|---|---|
| WM_CAP_SET_CALLBACK_CAPCONTROL | Specifies the callback function in the application called to give precise control over capture start and end. You can also use the capSetCallbackOnCapControl macro to send this message. |
| WM_CAP_SET_CALLBACK_ERROR | Specifies the callback function in the application called when an error occurs. You can also use the capSetCallbackOnError macro to send this message. |
| WM_CAP_SET_CALLBACK_FRAME | Specifies the callback function in the application called when preview frames are captured. You can also use the capSetCallbackOnFrame macro to send this message. |
| WM_CAP_SET_CALLBACK_STATUS | Specifies the callback function in the application called when the status changes. You can also use the capSetCallbackOnStatus macro to send this message. |
| WM_CAP_SET_CALLBACK_VIDEOSTREAM | Specifies the callback function in the application called during streaming capture when a new video buffer becomes available. You can also use the capSetCallbackOnVideoStream macro to send this message. |
| WM_CAP_SET_CALLBACK_WAVESTREAM | Specifies the callback function in the application called during streaming capture when a new audio buffer becomes available. You can also use the capSetCallbackOnWaveStream macro to send this message. |
| WM_CAP_SET_CALLBACK_YIELD | Specifies the callback function in the application called when yielding during streaming capture. You can also use the capSetCallbackOnYield macro to send this message. |
The following topics describe the different callback functions, the notifications sent to the functions, and their uses.