The MCI_PLAY and MCI_RECORD messages request that a device start playing or recording. Without any flags, your driver should assume the current position is the start position and the end of the media is the stop position. The MCI_FROM and MCI_TO flags will override the default positions. The units assigned to these position values depend on the device and the options set with the MCI_SET command message.
The MCI_STOP command stops the playing or recording of a device. If MCI_STOP applies to your device driver, your device driver should also support the MCI_PAUSE command. If possible, MCI_PAUSE should only suspend operation and leave the device ready to resume playing or recording immediately.
Your device driver can include the MCI_RESUME command message to restart a paused device. This command does not change the stop position. An application can use MCI_PLAY or MCI_RECORD to resume operation from a stopped or paused state for the respective modes. These commands resume operation under the following conditions:
Pausing and resuming a device does not change notification for the play and recording commands. These command messages do not prevent a device from obtaining the notification conditions-they only delay the command. Thus, a paused device can reach the notification conditions after it is resumed.