| Parameters | DWORD lParam1 | The following flags apply to all devices supporting MCI_SET: |
| MCI_NOTIFY | Specifies that MCI should post the MM_MCINOTIFY message when this command completes. The window that receives this message is specified in the dwCallback field of the data structure identified by lParam2. | |
| MCI_TEST | Queries the device to determine if it can execute the command. The device returns an error if it is incapable of executing the command. It returns no error if it can handle the command. MCI returns control to the application without executing the command. | |
| MCI_WAIT | Specifies that the set operation should finish before MCI returns control to the application. | |
| MCI_SET_AUDIO | Specifies an audio channel number is included in the dwAudio field of the data structure identified by lParam2. This flag must be used with MCI_SET_ON or MCI_SET_OFF. Use one of the following constants to indicate the channel number: |
| MCI_SET_AUDIO_ALL | Specifies all audio channels. This constant affects the left and right audio channel simultaneously. | |
| MCI_SET_AUDIO_LEFT | Specifies the left channel. | |
| MCI_SET_AUDIO_RIGHT | Specifies the right channel. | |
| For digital-video devices, the audio presentation source might be either the external input or the workspace. While digital-video devices should use the MCI_SETAUDIO commands to control audio, they still must support this flag. The default value for audio after an open is all on. |
| MCI_SET_DOOR_CLOSED | Instructs the device to close the media cover (if any). Digital-video devices return MCIERR_UNSUPPORTED_FUNCTION. | |
| MCI_SET_DOOR_OPEN | Instructs the device to open the media cover (if any). Digital-video devices return MCIERR_UNSUPPORTED_FUNCTION. | |
| MCI_SET_TIME_FORMAT | Specifies a time format parameter is included in the dwTimeFormat field of the data structure identified by lParam2. Specifying MCI_FORMAT_FRAMES in dwTimeFormat indicates that subsequent commands will use frames for the units. Digital-video devices use a default format of frames and might not support other formats. Constants defined for time formats include: |
| MCI_FORMAT_FRAMES | Specifies frames. | |
| MCI_FORMAT_MILLISECONDS | Specifies milliseconds. |
| MCI_SET_VIDEO | Sets the video signal on or off. This flag must be used with either MCI_SET_ON or MCI_SET_OFF. Devices that do not have video return MCIERR_UNSUPPORTED_FUNCTION. | |
| MCI_SET_ON | Enables the specified video or audio channel. | |
| MCI_SET_OFF | Disables the specified video or audio channel. |