User's Manual Part 2

Tech-X Flex User Guide - Firmware v06.50 Tech-X Flex
®
(NG2)
6-50
Intro
Overview
Wi-Fi
Ethernet
System
IP/Video
MoCA
RF
Specs
Additional video testing notes
About the IP address specified for testing
The IP address specified must reflect the destination IP address for video stream packets; that is, the first
address contained in the IP packet headers. For a multicast stream, this will be a multicast IP address,
not an IP address of a host on the network under test. For a unicast stream, this must be the IP address
of the destination device on the network, such as a set-top box (STB).
About encrypted (scrambled) signals and frame type recognition
The analysis software does not perform any decryption of scrambled signals. For monitoring a scrambled
stream, this can affect the ability to recognize frame types because the type indicator data may be
encrypted as well. Because perceived effect of packet loss varies widely according to the type of frame
whose data was lost, the frame type is an important component when packet loss is evaluated. Therefore
the software exhibits the following behavior with regards to frame type recognition:
• If the signal is not scrambled, the software should be able to recognize frame types according to
explicit data in the stream and precisely associate lost packets with the respective type.
• If frame type data is encrypted but frame boundaries can be discerned, the software heuristically
attempts to determine frame type based on relative data size and expected patterns.
• If frames cannot determined at all, the software uses default GOP structure and length information
specified when the analysis is launched to interpolate the probabilities of packet loss occurring within
any given frame type. Over time, if the defaults accurately reflect the GOP setup of the stream, the
measurements and estimations should be statistically correct.
While the lack of decryption by the software may appear initially as a limitation, it actually provides much
more flexibility with deployment and ease of maintenance. With the ability to interpolate encrypted frame
types, users are not required to maintain and deploy decryption algorithms that require processing time,
change periodically, and may be expensive and/or difficult to license.
4 Good Perceptible. Degradation can detected, but does not
adversely impact the viewing experience.
3 Fair Slightly annoying
2 Poor Annoying
1 Bad Very annoying or no stream present
Score Quality Human perception of degradation
Preliminary issue - Limited distribution only!