This 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.
wParam = (WPARAM) hInputDev
lParam = (LONG) lpwvhdr
Handle to the waveform-audio input device that received the data.
Pointer to a WAVEHDR structure that identifies the buffer containing the data.
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.