Digital Alert Systems DASDEC II User Manual page 108

If standard MPEG2 transport stream delivery is used, then the following option to select In-Band or Out-of-
band communication is available:
In-Band. Check to Enable. If not checked (disabled) then Out-of-Band (OOB) communication of the DVS-
644/SCTE18 message is made.
Discussion: The DVS-644/SCTE18 Cable Alert Message is an MPEG2 system table structure. It is typically
placed into the MPEG2 Transport stream and routed to the downstream cable set top boxes (STB) or SCTE-18
enabled TV's. Thus the ultimate target for the DVS-644/SCTE18 alert message is a set-top box (STB) or a cable
ready TV. Keep in mind that the actual EAS alert handling is performed by the STB or TV. Although standard
practices exist for these actions, some differences can and do exist. The processing of the Cable Alert Message
on the STB determines the actual response to the alert seen by a viewer. For alerts below a certain priority (by
default, this would be the highest priority, 15), a crawl message is typically run on the video display for every
channel. For alerts at or above this priority, the video channel is forced to a details channel. Based upon whether
this channel is available at the STB as In-Band or Out-of-Band, set the Details Major/Minor number or the
Details Video/Audio OOB channel numbers. This details channel is where the highest priority force tune alerts
are switched. EAN/EAT will always cause a force tune to this channel.
Details Video OOB ID/ Details Audio OOB ID - When the alert details channel is an Out-of-Band channel; set
the provided video/audio channel field. An audio channel designation is not required when there is another
means to provide the alert audio. A value of 0 means not used.
Details In-Band Major/Minor Channel - These two fields are for programming the digital in-band Major/Minor
channel number of the in-band force tune details channel. A value of 0 means not used.
Exception Channel List - This interface allows specific In-Band and Out-of-Band channels to be excluded from
the alert response of the STB. These channels will have their own EAS. When enabled, the interface controls
allows creation of any number of exception channels.
MPEG Audio Sync Private Descriptor - Check to enable the MPEG Audio Sync Private Descriptor method.
This is a special private descriptor for synching a DASDEC II MPEG2 A/V stream to the DVS644/SCTE18
message processor. Use of this method requires custom support by the DVS644/SCTE18 message processor.
NDS Tune Private Descriptor - Check to enable the NDS Tune Private Descriptor method. This is a special
private descriptor for synching a DASDEC II to an NDS system. Use of this method requires custom support by
the DVS644/SCTE18 message processor.
Private Descriptor Interface
Generic Private Descriptor Check to enable an interface to create one static DVS644/SCTE18 Private
Descriptor. Use of this method requires custom support by the DVS644/SCTE18 message processor.
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Digital Alert Systems: DASDEC User Manual