Using a Window or Thread to Process Driver Messages

To use a window callback function, specify the CALLBACK_WINDOW flag in the fdwOpen parameter and a window handle in the low-order word of the dwCallback parameter of the waveInOpenDZFQLF or waveOutOpen2MUO.P_ function. Driver messages will be sent to the window procedure for the window identified by the handle in dwCallback.

Similarly, to use a thread callback, specify CALLBACK_THREAD and a thread handle in the call to waveInOpen or waveOutOpen. In this case, messages are posted to the specified thread instead of to a window.

Messages sent to the window or thread callback are specific to the audio device type used. For more information about these messages, see Playing Waveform-Audio Files40DX031.