The WM_CAP_GET_USER_DATA message retrieves a LONG data value associated with a capture window. You can send this message explicitly or by using the capGetUserData macro.
WM_CAP_GET_USER_DATA
wParam = (WPARAM) 0;
lParam = 0L;
Returns a value previously saved by using the WM_CAP_SET_USER_DATAmessage.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in vfw.h.
Video Capture Overview, Video Capture Messages, capGetUserData, WM_CAP_SET_USER_DATA