Commands directly interpreted by MCI.Your application controls MCI devices by sending commands to devices. MCI commands can be divided into the following categories:
Commands directly interpreted by MCI.
Commands supported by all MCI devices.
Commands that are optional (if a device uses an optional command, it must respond to all flags for that command that apply to the device type).
Commands specific to a device type or class; for example, videodisc players or digital audio tape recorders (these commands contain both unique commands and extensions to commands supported by other devices).
The following list summarizes the command messages that are handled directly by the system rather than being passed on to MCI devices:
| Message | Description |
| MCI_SYSINFO | Returns information on MCI devices. |
| MCI_BREAK | Sets a break key for a specified MCI device. |
| MCI_SOUND | Plays system sounds identified in the [Sounds] section of the WIN.INI file. |
The following list contains command messages supported by all MCI devices:
| Message | Description |
| MCI_CLOSE | Closes an MCI device. |
| MCI_GETDEVCAPS | Obtains the capabilities of an MCI device. |
| MCI_INFO | Obtains information from an MCI device. |
| MCI_OPEN | Initializes an MCI device. |
| MCI_STATUS | Returns status information from an MCI device. |
The following list summarizes the optional command messages (if a device supports a particular command message, it must respond to all flags that apply to that device type):
| Message | Description |
| MCI_LOAD | Loads data from a disk file. |
| MCI_PAUSE | Pauses playing or recording. |
| MCI_PLAY | Starts transmitting output data. |
| MCI_RECORD | Starts recording input data. |
| MCI_RESUME | Resumes playing or recording. |
| MCI_SAVE | Saves data to a disk file. |
| MCI_SEEK | Seeks forward or backward. |
| MCI_SET | Sets device information. |
| MCI_STATUS | Returns status information from an MCI device. (Additional flags for this command supplement those for the command in the previous table.) |
| MCI_STOP | Stops playing or recording. |
MCI devices can have additional command messages or extend the definition of the command messages presented in the previous lists. You can find examples of extended messages in the audio and animation chapters of this workbook. The Programmer's Reference contains a complete description of each command message.