| Microsoft DirectX 8.1 (C++) |
The GetParamEx method retrieves data from a track. This method is similar to IDirectMusicPerformance8::GetParam but adds support for self-controlling segments. It is used chiefly by tools.
Syntax
HRESULT GetParamEx(
REFGUID rguidType,
DWORD dwTrackID,
DWORD dwGroupBits,
DWORD dwIndex,
MUSIC_TIME mtTime,
MUSIC_TIME* pmtNext,
void* pParam
);
Parameters
rguidType
Reference to (C++) or address of (C) the identifier of the type of data to obtain. See Standard Track Parameters.
dwTrackID
Unique identifier of a track within the segment state from which the parameter is to be obtained. Every performance message that originates from a track carries an identifier of the track instance that generated the message. This identifier is kept in the dwVirtualTrackID member of the DMUS_PMSG part of the message structure. When this value is passed to GetParamEx, the method is able to determine whether the track is self-controlling, in which case it gets its data from another track in the same segment rather than in the control segment.
dwGroupBits
Group that the track is in (see Remarks). Set this value to 0xFFFFFFFF for all groups.
dwIndex
Index of the track in the group.
mtTime
Time from which to obtain the data, in performance time.
pmtNext
Address of a variable that receives the time (relative to mtTime) until which the data is valid. If this returns a value of 0, either the data is always valid, or it is not known when it might become invalid. If this information is not needed, pmtNext can be set to NULL. See Remarks.
pParam
Address of an allocated structure in which the data is to be returned. The structure must be of the appropriate kind and size for the data type identified by rguidType.
Return Values
If the method succeeds, the return value is S_OK.
If it fails, the method can return one of the error values shown in the following table.
| Return code |
| DMUS_E_GET_UNSUPPORTED |
| DMUS_E_NO_MASTER_CLOCK |
| DMUS_E_NOT_FOUND |
| DMUS_E_TRACK_NOT_FOUND |
| E_POINTER |
Remarks
Each track belongs to one or more groups, and each group is represented by a bit in dwGroupBits. For more information, see IDirectMusicSegment8::InsertTrack and Identifying the Track.
Requirements
Header: Declared in dmusici.h.
See Also