The MM_WIM_DATA message is sent to a window when waveform-audio data is present in the input buffer and the buffer is being returned to the application. The message can be sent either when the buffer is full or after the waveInReset function is called.
MM_WIM_DATA
wParam = (WPARAM) hInputDev
lParam = (LONG) lpwvhdr
This message does not return a value.
The returned buffer might not be full. Use the dwBytesRecorded member of the WAVEHDR structure specified by lParam to determine the number of bytes recorded into the returned buffer.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in mmsystem.h.
Waveform Audio Overview, Waveform Messages, waveInReset, WAVEHDR