Alcorn Mcbride Digital Video Machine 4, Руководство пользователя

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Playlists 39
Playlist Example using ‘AND’ operator
;play a series of videos and load a new banner with each new video
; Play Toothbrush Ad – Show Current Price on Banner
5PL AND $2.99BT
; Play Short Entertaining Movie
6PL
; Play Potato Chip Ad – Show Current Prices on Banner
7PL AND $1.99BT
; Repeat
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This example shows how the AND operator can be useful. To understand why,
think back to the last example. Remember that a command is not executed until
the command prior to it has completed. Now, looking at the current example,
we need to do 2 things simultaneously. We need to play a video and display a
banner at the same time, but we do not want to wait until the video is over
before displaying the banner. This is where the
AND operator becomes useful.
By placing the AND operator between commands, we can instruct the playlist
engine to execute those commands without waiting for the others to complete.
This causes the playlist engine to execute all of these commands simultaneously,
and then wait for all of them to complete before it advances.
To understand this concept, let’s step through the example above. First, the
playlist engine sees the
5PL command. Just like before, it inserts the channel
number and then sends the command to the Command Engine to start playback.
At this point, the playlist would normally wait for the video to complete before
doing anything else. However, since an
AND operator is present after the
current command, the playlist engine executes that command immediately after
the play command. The playlist engine will now wait for both of these
commands to finish before moving on to the next command.
NOTE: The AND operator can be used more than once if needed. You can
execute any number of commands simultaneously if needed.