A list of QMP's command line options is available by clicking Menu → About QMP… → Q Tips. If for any reason you cannot access them that way, you can find them below.
*/play Start playing
*/play d:\trackXX.cda Play track 'XX' on CDROM 'd:'
*/play c:\mediafile Play 'mediafile'
*/add c:\mediafile Add 'mediafile' to the playlist
*/pause Pause CD (if playing)
*/stop Stop CD (if playing)
*/trkfwd Next track (if playing)
*/trkbwd Back one track (if playing)
*/eject d: Eject CDROM 'd:'
*/ejectall Eject all CDROMs
*/closeall Close all CDROMs
*/autoplay Used for windows CD auto play feature,
won't override QCD's current state.
*/ontop Set QCD to be on top of all windows
*/notontop Unset QCD to always be on top
*/hide Minimize QCD
*/show Shows QCD
*/noactivate append this option to stop activation of
player with any of the above commands
*/shutdown Shutdown QCD
*/safestart Runs QCD without initializing plugins
*/newinst Runs multiple instance of QCD
*/class classname Runs QCD with different window classname