Inter-Zone Synchronisation

If the playlists in two zones show the same number of items for the same durations then you might expect the pairs of items in the two zones to appear on the display screen simultaneously. Each playlist, however, has it's own clock which cannot be guaranteed to remain in perfect synchronisation over a long period of time. The inter-zone synchronisation mechanism should be used instead.

Inter-zone synchronisation is implemented by designating one playlist as the "Master" and the other as the "Slave". There can be more than one slave.

The slave playlist has a named point inserted into it. The master has a command of the same name inserted into it. When the master playlist reaches the command it calls all slaves to stop doing what they are doing and to jump to the next item after the named point.

The named points are known as "Rendezvous Points" and the commands are known as "Advance To" commands (or "Advance to Rendezvous Point X").

Typically, a Rendezvous Point named "start" is inserted at the beginning of the slave playlists and an Advance To "start" is inserted at the beginning of the master playlist. Thus, each time the master playlist restarts, all slaves will be forced to restart, even if their clocks have fallen out of synchronisation with the master's clock.

Adding Rendezvous Points

In the Playlist Editor for each slave playlist, go to the 'Specials' tab.
Type the name into the "Rendezvous Point" text box. The name can be anything as long as it does not start with 'auto_'. Make sure that the same name is entered into each slave playlist.
Click 'Add'.
Use the arrow buttons in the yellow 'Playlist' area to position the Rendezvous Point.

Adding an Advance To Command

In the Playlist Editor for each slave playlist, go to the 'Specials' tab.
Select the Rendezvous Point by name from the list in the "Advance To Rendezvous Point" section.
Click 'Add'.
Use the arrow buttons in the yellow 'Playlist' area to position the Advance To command.
Click the 'Activate' button.

Captioning

It is possible to show captions in one zone and the related videos in another. Since the duration of a video is not known accurately, setting durations on text items in the captions playlist will result in the two zones falling out of synchronisation. A more advanced method of Inter-Zone Synchronisation is required than in the previous chapter.

This method can also be used to add captions to images or match images to videos and so on.

The video playlist must be the master and the text playlist must be the slave. A Rendezvous point must be inserted before each item in the text playlist and a matching Advance To command must be inserted before each video in the video playlist. The durations for all items in the text playlist must be indefinite. The video playlist will then trigger each new item in the text playlist.

It is possible, however, to achieve all of the above automatically.

Automatic captioning:

Put all the videos into one folder on the NTB.
Click on the video zone to open its playlist for editing.
Browse into the folder in the blue 'Folders' tab
Click on the 'Add Folder to Playlist' button alongside the folder name in the green 'Files' tab to add it to the playlist as a folder-play item.
Click the 'Edit' button for the folder-play in the yellow 'Playlist'.
In the 'Folder Synchronisation' section, select 'Master'
Click the 'Apply' button.
Write the caption for each video into a text file of the same name as the video (e.g. the video "Highlights part 1.mpg" will have a matching text file named "Highlights part 1.txt")
Place all the text files into a folder on the NTB. The folder can be the same one that contains the videos.
Click on the text zone to open its playlist for editing.
Add the text folder as a folder-play item to the playlist (as above).
Click the 'Edit' button for the folder-play in the yellow 'Playlist' tab
In the "Folder Synchronisation" section, select 'Slave'
Ensure that the duration is indefinite and that the text is stationary.
Click the 'Apply' button.

Video On Demand

If an NTB has an Advanced Ad-Hoc license then videos can be shown on the display screen on-demand (i.e. when someone clicks a button) by making advanced use of the Inter-Zone Synchronisation feature.

The same mechanism can also be used to set up images or any other media type on-demand.

By inserting Rendezvous Points and Advance To commands into THE SAME playlist, it is possible to create loops, or sub- playlists, within the playlist.

At the start and of each sub-playlist is a Rendezvous Point and there is a matching Advance To command at the end of the sub-playlist. Thus the playlist will loop between the two points indefinitely or until an Advance To command from somewhere else instructs the NTB to break out of the loop.

Sub-Playlist Loops

Click on a zone to edit its playlist
Click on the 'Specials' tab.
Type the name of the first loop into the "Rendezvous Point" text box (make the name as descriptive as possible)
Click the 'Add' button to add the Rendezvous Point to the playlist.
Add the items that must appear in the sub-playlist in the usual manner. If you want a sub-playlist to play just once then insert an image at the end with an indefinite duration.
In the pink 'Specials' tab, select the Rendezvous point by name from the "Advance To Rendezvous Point" list and click the "Add" button.
The sub-playlist is now complete. To insert another sub- playlist, repeat the above procedure.
Make the Layout live (e.g. add it to the diary and click the 'Activate' button).
Switch between playlists by adding options to an Ad-Hoc Page and then selecting them (see below).

Add Advance-To Options to an Ad-Hoc Page

Browse to 'Ad-Hoc Items | Add'.
Select ;Advance-To' type and give the item a name (e.g "Movie selection")
In the 'Ad-Hoc Items' tab click 'Edit' for the item.
Tick all the Rendezvous points that you want to appear in the list of options.
Click 'Save'.
Browse to 'Ad-Hoc Pages | Add'.
Enter a title for the new page (e.g. "Movie Control").
In the pink 'Add' tab, add the Item that you have just created to the page that you have just created.
In the green 'Properties' tab, tick all the users that should be allowed to call the commands.
Click 'Apply'.

Break out of a Sub-Playlist on Demand

Browse to the 'Ad-Hoc Pages' and then to the page created above.
Select the rendezvous point from the drop-down list.
Click 'Save'.

Developers Guide to Sending Advance To Commands

Advance To commands can also be sent programatically. The advance_to command is an XML message that must be posted at the HTTP port of the NTB. The command takes the form:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <advance_to id="NAME" >

where "NAME" is the case-sensitive name of the desired rendezvous point in the PlayList.