LOCK TUNER (Myth Protocol)
Command arguments: <int:cardid> OPTIONAL
List arguments: none
Response: <int:cardid> <videodevice> <audiodevice> <vbidevice>
Asks the backend to lock a tuner. Locked tuners will not be used for scheduled recordings and are not available for use by other frontends. The backend will attempt to re-schedule recordings to take this into account. The tuner should be released when no longer required using FREE_TUNER.
If no card ID is specified, the backend will choose an unlocked, unused tuner.
The ID of the card if successful, -1 if no card can be found with the specified ID or -2 if the tuner is already locked. If no card ID was specified, then a return of -1 indicates that all tuners are either locked or are currently in use.