Wegener Communications 6420 - Manual (Page 85)

iPump 6420 User’s Manual
www.wegener.com 800070-01 Rev B Chapter 3, Page 81
3.4.3. Timing Model
The timing model for insertion of file audio into the live audio stream is illustrated by the
example shown in Figure 3-17. From the audio feed and companion closures emitted by the
customer’s automation system looking forward, WEGENER’s Compel and iPump6420 both
provide tools to align the local file insertion onto a network “avail”. This is, in a non-hard-time
system, the opportunity to substitute local file content for network-wide audio material, usually a
default network commercial spot.
Viewing the figure, we see the sum total of all significant delays to the live audio stream.
This is shown as “Live audio delay”. Meanwhile, we can see the sum total of all significant
delays, in the system, to actual insertion of the file audio content. This is shown as “COMPEL-
cmd’d Insertion delay”. The difference between the two terms is called the “Insertion Timing
Error”. Note that this value is minimized when the sum of “NETCON delay” and “iPump
COMPEL cmd delay” equals the delay through the uplink MPEG audio compression system.
The first term can mean the traditional legacy NETCON DELAY command used in Compel
macros, or it can mean the newer Delay term in the Compel Command Extended Syntax. The
iPump Compel Cmd Delay is an i6420 setting, usually set by the factory, but WEGENER can
advise customers on how to adjust this in their field i6420s.
The non-hard-time system shown is not the only example for using local file insertions. In
some hard-time systems, file inserts may be scheduled in the iPump6420 Local Scheduler. In
these cases, if an insert is scheduled for a specific time, then the file insertion command is
executed instantly per the i6420’s real-time clock, and the only delay to seeing the file audio
appearing in the final audio output is the standard 500 mS audio buffer delay.
Relevant user controls are:
1. Compel Cmd Delay setting (factory setting)
2. NETCON DELAY Compel command OR
3. Compel Extended Syntax command delay