MMProgRef - Notification Messages

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Multimedia Programming Reference

Introduction What's New... MCI Functions High-Level Macro Service Functions Subsystem Messages Notification Messages MCI Command Messages String Commands Memory Playlist Commands Graphic Button Control Secondary Window Functions MMIO Functions MMIO Messages CODEC Messages DIVE Functions Real-Time MIDI Functions SPI Functions Data Stream State Table SMH Messages DDCMD Messages VSD Commands SHD Messages SHC Messages Data Types Types of MIDI Messages Multimedia Specification Overview Resource Interchange File Format Multimedia File Formats RIFF Compound Files and Elements - Sharing and Access Return Codes Notices Glossary

The system uses notification messages to respond to applications, indicating system status such as completion of a media device function or passing of the ownership of a media device between processes.

Messages are returned to applications **asynchronously** (using **WinPostMsg**), except for MM_MCIEVENT, which is sent **synchronously** (using **WinSendMsg**). A media control interface call that results in the dispatch of these two messages (such as MCI_OPEN and MCI_ACQUIREDEVICE) must be issued from application threads that have a message queue.

All messages except system messages operate in an asynchronous mode without notification unless **MCI_NOTIFY** or **MCI_WAIT** is specified. These two flags are mutually exclusive. If both are used, an **MCIERR_FLAGS_NOT_COMPATIBLE** error is returned. If **MCI_WAIT** is used, control is not returned to the caller until the command completes. **MCI_NOTIFY** returns control to the caller and then completes the command. A notification will be sent to the application if **MCIERR_SUCCESS** was returned on the call.

The second parameter specified for each message is a pointer to a control block structure associated with that message. This pointer is passed in the *pParam2* parameter of mciSendCommand.

Function	Description
MM_MCICUEPOINT	Notifies application that a cue point is found in a playlist, or that a cue point has been detected, which was set with the MCI_SET_CUEPOINT message.
MM_MCIEVENT	Notifies application of an event generated by a device.
MM_MCINOTIFY	Notifies an application after a device completes action or an error occurs.
MM_MCIPASSDEVICE	Notifies application that a shared device is being gained or lost.
MM_MCIPLAYLISTMESSAGE	Notifies application that playlist processor has found a MESSAGE instruction.
MM_MCIPOSITIONCHANGE	Notifies applications of current media position.