Alcorn Mcbride Digital Video Machine 4, User Manual

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Playlists 41
Playlist Example – Synchronizing Channels
;play 4 channels in sync using 1 playlist (search to channel 1)
; Assign all 4 channels to group #1
1AG AND CHANNEL[2] 1AG AND CHANNEL[3] 1AG AND CHANNEL[4] 1AG
; Play files 1,2,3, and 4 in sync on all 4 channels
1PL AND CHANNEL[2] 2PL AND CHANNEL[3] 3PL AND CHANNEL[4] 4PL
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This is a fairly complex, yet common, use of playlists. This method is necessary
if you wish to synchronize the video playback of more than one channel.
The first thing that is probably unfamiliar in this example is the CHANNEL[X]
operator. Even though this playlist is searched to only one channel (Channel
#1), we need it to have the ability to control ALL channels to maintain
synchronization. Remember that, by default, the channel number that the
playlist ‘belongs to’ is automatically inserted into the command. Well, if we
wish to send a command to a different channel, we need change the number that
is being inserted. This is exactly what the
CHANNEL[X] operator does.
By preceding a command with CHANNEL[X] , the number X is inserted in the
command instead of the default channel. To demonstrate, the above playlist
would translate into the following commands before being sent to the Command
Engine.
1 1 AG 1 2 AG 1 3 AG 1 4 AG
1 1 PL 2 2 PL 3 3 PL 4 4 PL
Knowing this, you can see how this playlist will behave. First, the AG
commands will be sent to channels 1, 2, 3,and 4. This will group these channels
together, allowing them to frame-sync to each other. When all for of these
assignments are complete, the playlist will send the
PL commands to channels
1,2,3, and 4 simultaneously. Just like the previous examples, the playlist will
hold here until all four videos have completed playback.
NOTE: It is very important that you NOT use commands that do not use the
channel field. This includes the
Group commands!