The ICM_GETSTATE message is sent to a video compression driver to have it fill a block of memory describing the compressor’s current configuration.
If dwParam1 is NULL, the driver returns the size of the configuration information. If dwParam1 is not NULL, and the value received in dwParam2 is less than size of the configuration information, the driver returns zero. Otherwise the driver returns the size of the information it returns in the structure supplied by dwParam1.
Client applications send this message with dwParam1 set to NULL to determine the size of the memory block required for obtaining the state information.
The data structure used to represent state information is driver-specific and is defined by the driver.