An application can set a wait or a notify flag on a device command sent with mciSendString or mciSendCommand. These two flags are mutually exclusive and are available on all commands except some system commands.
旼컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿑lag 쿏escription � 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 퀇ait 쿟he command is executed synchronously. The � � 쿯unction waits until the requested action is � � 쿬omplete before returning to the application.� 쳐컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿻otify 쿟he command is executed asynchronously, � � 쿪llowing control to be returned immediately � � 퀃o the application. When the requested � � 쿪ction is complete, an MM_MCINOTIFY message � � 쿶s sent to the application window procedure. � 읕컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�
Note: If a command is issued without a wait flag or notify flag specified, the command is executed asynchronously, and the application is never notified.
The wait flag is useful for operations that are conducted quickly, like the playback of short sounds, which the application wants to complete before it continues. The wait flag is also useful for operations that return information, such as device capabilities, because the Media Device Manager parser converts the return code to a meaningful string. However, the conversion occurs only if the wait flag is specified.
The wait flag should be used with care when issuing commands from threads that read application input message queues as it ties up the thread, preventing all PM messages in the system from being processed while the command issued with the wait flag is executed.
The notify flag is useful for operations that are conducted over a period of time. For example, the playing of a waveform file often can take a while to complete. By specifying the notify flag, an application requests to be notified when processing of the command is complete. The application window procedure can then remain responsive to input queue processing.