IDirectMusicTrack8::Play

The Play method causes the track to play. It performs any work that the track must do when the segment is played, such as creating and sending messages.

Syntax

HRESULT Play(
  void* pStateData, 
  MUSIC_TIME mtStart,
  MUSIC_TIME mtEnd,
  MUSIC_TIME mtOffset
  DWORD dwFlags, 
  IDirectMusicPerformance* pPerf, 
  IDirectMusicSegmentState* pSegSt,
  DWORD dwVirtualID
);

Parameters

pStateData

Pointer to state data from the IDirectMusicTrack8::InitPlay method. The format and use of the data is specific to the track.

mtStart

Start time.

mtEnd

End time.

mtOffset

Offset to add to all messages sent to IDirectMusicPerformance8::SendPMsg.

dwFlags

Flags that indicate the state of this call. See DMUS_TRACKF_FLAGS. A value of 0 indicates that this call to Play continues playback from the previous call.

pPerf

Performance used to allocate and send messages.

pSegSt

Segment state that this track belongs to. The IDirectMusicSegmentState8::QueryInterface method can be called to obtain an IDirectMusicGraph8 interface—to call IDirectMusicGraph8::StampPMsg, for instance.

dwVirtualID

Virtual identifier of the track. This value must be put in the dwVirtualTrackID member of any message (see DMUS_PMSG) that is sent by IDirectMusicPerformance8::SendPMsg.

Return Values

If the method succeeds, the return value can be S_OK or DMUS_S_END.

If it fails, the method can return one of the error values shown in the following table.

Remarks

If the track is empty, the method returns DMUS_S_END.

Tracks generate messages in a medium-priority thread. You can call time-consuming functions, such as code to stream data from a file, from within a track's Play method. However, be sure to follow the guidelines for safe multithreading.

Requirements

  Header: Declared in dmplugin.h.

See Also

• IDirectMusicTrack8 Interface
• IDirectMusicTrack8::PlayEx