Triple-Play Service Deployment

Chapter 6: Troubleshooting Video in the Headend
Encoders
Interoperability and Segmentation
The preceding examples have illustrated how testing digital video
in the headend primarily consists of testing MPEG transport
streams. Access to the TR 101-290 status, PSI decodes, PCR
measurements, and visibility to the PIDs and programs gives the
technician a comprehensive toolbox for validating the integrity of
the digital video while in transport, and troubleshooting the issues
that have been observed. But even equipped with this toolset, the
technician is limited if the ability to apply it at various points across
the broadcast chain is not present. MPEG transport is a horizontal
technology. From encoder to set top box, digital video
programming runs in an MPEG-2 transport stream. When those
programs enter the IPTV headend at ingress, they arrive in MPEG
transport. Leaving at the egress, they are in MPEG transport. These
programs can be monitored at the egress of the IPTV headend,
proactively detecting MPEG problems. TR 101-290 is an excellent
foundation for that monitoring, but this indicates only when the
problems exist and what they are. It cannot identify where the
problems originated. The best way to accomplish this is to use an
MPEG test to segment the broadcast chain and test at each node
where the MPEG programs have been modified or otherwise
handled. Figure 6.10 illustrates a generic broadcast chain common
to an IPTV system.
MPEG-2 TS
(RF)
IRDs
Figure 6.10: Test points for testing interoperability
MPEG-2 TS
(DVB-ASI)
Transcoders
MPEG-2 TS
over IP
(Copper GigE))
IP
Media Switch
167
Core
Network