Question

To recognize a media i use SHGetDriveMedia;
on the second parameter I pass pdwMediaContent for reference and the api
insert the type of content.
However, the recognition is done asynchronously. How can I know when the api
has finished the recognition?

Answer 1

It’s not asynchronous. When you call it right after putting the disk in the drive, it’s in “sniffing phase”, trying to determine what method of autoplaying the disk should be used. There are several detection phases that can be returned in the ARCONTENT flags when the function returns:

ARCONTENT_PHASE_UNKNOWN (0x00000000)
  Introduced in Windows Vista. AutoPlay is searching the media. The phase of the 
  search (presniff, sniffing, or final) is unknown.

ARCONTENT_PHASE_PRESNIFF (0x10000000)
  Introduced in Windows Vista. The contents of the media are known before the 
  media is searched, due to the media type; for instance, audio CDs and DVD movies.

ARCONTENT_PHASE_SNIFFING (0x20000000)
  Introduced in Windows Vista. AutoPlay is currently searching the media. Any 
  results reported during this phase should be considered a partial list as more 
  content types might still be found.

ARCONTENT_PHASE_FINAL (0x40000000)
  Introduced in Windows Vista. AutoPlay has finished searching the media. Results 
  reported are final.

ARCONTENT_PHASE_MASK (0x70000000)
  Introduced in Windows Vista. A mask that denotes valid ARCONTENT_PHASE values.

This seems to indicate (based on the text with ARCONTENT_PHASE_FINAL above) that you should expect to need to call this function more than once, until you receive that value in the flags returned, at which point you can check the other values in the flag for disk type.