This method sets the number of tracks in the play list.
HRESULT put_NumTracks( unsigned char bcTracks );
NOERROR indicates success. E_INVALIDARG indicates that an invalid argument has been entered—for example, if the number of tracks exceeds the maximum number allowed.
The index of tracks in the play list begins at 1. If your application determines that no tracks are available, set the number of tracks equal to 0. The maximum number of tracks available is ASFC_PLAYLIST_TRACKSMAX, which is defined as 128.