Triple-Play Service Deployment

Chapter 6: Troubleshooting Video in the Headend
– Scenario B: PTS errors. Upon checking TR 101-290, the technician finds that
no errors are being reported in any of the Priority 1 or 2 parameters. The
stream is compliant. This would suggest that the issue is either occurring
downstream of the technician’s test point or is content specific, in other
words, native to the audio. If the technician’s charter is to maintain the
headend, the technician should not be concerned with events happening
downstream. To be thorough, the technician should check the PAT and PMT
information and verify that there is an audio PID in the transport for this
program when it leaves the headend. When this is accomplished, the
technician may look more deeply into the PTS for the audio. If the technician
immediately notices that there is a significant delta between the PTS value for
the video and the PTS value for the audio, the problem will be identified.
These are the time codes for the presentation of these components, and they
should be very close in value. With the problem identified, the technician’s
task becomes determining the origin of the problem.
PTS values are created by the encoder and stored in the PES header, so the
technician should test at the input to the transcoder to determine whether
the PTS delta exists there. If it does not, this indicates a problem originating in
the transcoder. If it does, the next step is to test at the ingress stage. Testing
directly off the antenna or satellite is ideal because this enables the technician
to eliminate the IPTV headend from suspicion altogether. Assuming that the
MPEG analyzer has the appropriate RF interfaces, the technician must tune to
the program coming off air. If the PTS delta exists there, the technician can
ascertain that the source of the problem is the content provider. The
technician should record the stream, generate text reports, make screen
captures, and then contact the content provider immediately with the
evidence of this issue. Optimally, the technician’s analyzer will provide remote
access capability (VNC, Remote Desktop, etc), to connect immediately to the
Internet and transmit evidence of the problem directly to the content
provider.
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