An application uses the MCI_SET command message to set device information. An application will supply a pointer to an MCI_SET_PARMS structure. Your device driver should fill in the members of this structure as follows.
The MCI_SET_TIME_FORMAT flag sent by the application validates the dwTimeFormat member of MCI_SET_PARMS. The contents of dwTimeFormat specify the time format or position indicator the device wants to use with your device. If possible, your device driver should support the MCI_FORMAT_MILLISECONDS format in addition to any format that is conventionally used with the device.
When a time format is not specified, your device driver should assume a default time format. The following table lists the default formats for MCI device drivers:
MCI Device Type | Default Time Format |
cdaudio | MSF |
mmmovie | Frames |
overlay | Not applicable |
sequencer | Specified by the MIDI file element |
videodisc | HMS for CLV, Frames for CAV |
waveaudio | Milliseconds |
The MCI_SET_AUDIO flag sent by the application validates the dwAudio member of this structure. The contents of this member identify the audio channel affected by the MCI_SET_ON or MCI_SET_OFF flags. Constants defined for dwAudio include MCI_SET_AUDIO_ALL, MCI_SET_AUDIO_LEFT, and MCI_SET_AUDIO_RIGHT to indicate both channels, the left channel, and the right channel. Your device driver can use other values for additional channels.