Spirent Tech-X Flex, Руководство пользователя

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Base Unit User Guide Issue 1 Tech-X Flex™
5-12 5: IP and Video Testing
Intro
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GOP Length Number of frames in a group of pictures (GOP) on the stream, related to the
GOP type. This is essentially the I-frame update interval; that is, the number of
frames from one I-frame to the next. This value is used only as a default if the
actual frame types and GOP structure cannot be dynamically detected from the
stream.
Range:
1 - 100
Loss Sensitivity This defines how much the quality assessment should be sensitive towards
packet loss and discards. A higher value indicates the video stream is more
sensitive to packet loss/discard. When set higher, the calculation model will
respond more rapidly to packet loss on the network under test, and packet loss
will have a greater impact on the calculated score. If set lower, the results will be
less affected by packet loss. This setting makes the analysis tunable for different
varieties of encoders and various network environment conditions.
Concealment Level This parameter defines the effectiveness of the packet loss concealment
algorithm use by the encoder. A higher value indicates a better PLC algorithm.
This setting helps compensate for reduced packet loss due to regeneration by
technologies such as forward error correction (FEC). In other words, it affects
how sensitive the quality assessment is to packet loss, with some similarity to the
loss sensitivity setting. A higher setting indicates that overall packet loss will
affect the quality score less. A setting of zero or none indicates no concealment,
meaning that packet loss will have the most impact to video quality, with respect
to this parameter's influence.
Valid values are:
0 to 50
Complexity This parameter defines the video content coding factor. A higher value indicates
the video stream can be encoded using a lower bit rate to achieve a given
quality.
Valid values are:
-50 to 50
Table 5-6 Video QoS test - Setup parameters
Parameter Description