Here’s a little summary of the philosophy of PFL in mAirList.
Normal PFL
Normal PFL is always bound to a player (normal player or cart player). So you can only pre-listen to the item loaded into that player. The main use of normal PFL is to pre-listen to the item which you have already loaded because it is going on air next. Just issue the PLAYER x-y PFL ON command, and the player will go into PFL mode.
If the “Advanced PFL” option is set, you will also see the cue point editor (referred to as “Advanced PFL window”). Which allows you to change the cue points while the player’s PFL is active. There is no player in this window - as it is associated with an existing player somwhere else inside mAirList.
Unfortunately, the file is locked on disk while being loaded into the player, so you cannot rewrite the file tag in that situation. This is why there is no “Save to tag” button, and all changes are only saved to the local playlist.
The output of the normal PFL function can be routed to a dedicated sound card, but most people will set it to the same sound card as the on air output and use their desk’s PFL switch to route the signal to monitoring only. At eldoradio*, pressing the PFL button on the desk will automatically put the player into PFL mode. This makes pre-listening to scheduled items very easy for the presenter.
Extra PFL
Sometimes, you might also want to pre-listen to an item which is further down the playlist without loading it into a player beforehand, or to an item which is currently broadcasted in a player in order to listen to the ending (remember that the “simultaneous PFL and playback” option is brand new and only suitable if you have distinct playback and PFL sound cards defined for that player). This is what Extra PFL is for. It provides a way to pre-listen to any item found anywhere inside mAirList, by opening a window with a newly instantiated “extra” player object, which is then started in PFL mode. Additionally, that window contains the Advanced PFL controls from that player, embedded into that same dialog. In other word: It’s not a cue point editor window with a player, but a player window with an embedded cue point editor.
The Extra PFL operation is completely independent from any other player the item might be currently loaded into, and the output of that player is always routed to the Extra PFL sound card defined in the config.
The Extra PFL dialog does have a “save to tag” button, because the item is not necessarily loaded into any other player (only in the Extra PFL player object itself, but this one is destroyed when you click the button). If you try to save to a file which happens to be loaded in any other player, you will receive an error message if the item happens to be loaded somewhere else.
By the way - there are no VB3 controls anywhere inside mAirList. The Advanced PFL dialog is completely designed by hand. And mAirList is written in Delphi anyway 
If you have any ideas for visual improvement of the cue point editor, please let me know.
Torben
