Base Unit User Guide Issue 1
Tech-X Flex™
5-20
5: IP and Video Testing
Intro
Wi
-F
i
10/100
Sy
stem
IP/V
ideo
S
p
ecs
Digital video concepts overview
About basic video and audio compression
Compression techniques are vital to allow modern communication networks to handle the transmission
of packetized digital video. For example, without compression, a video stream with pixelized image
frames would require a large amount of data, far too much for efficient transport across networks to
multiple subscribers.
PCR Repetition Err
Number of times that the interval between PCR (program clock reference)
transmissions exceeded 100 ms, if the discontinuity indicator is not set. The PCR
is used as a time synchronization tool between the encoder and decoder. If the
discontinuity indicator is not set, the encoder expects a 100 ms or smaller interval
between PCRs. Both the PCR and discontinuity indicator are part of the packet
header.
PTS Err
Number of times that the PTS (presentation time stamp) repetition period
exceeded 700 milliseconds. The PTS is part of a packet header and indicates the
exact moment where a video frame or an audio frame has to be decoded or
presented to the user respectively. It is important for synchronization of the audio
and video streams.
Table 5-15 Video QoS - Transport results, Jitter/Delay Stats tab
Result
Description
MAPDV
The true average mean-absolute packet delay variation in milliseconds. This type
of measurement is sometimes referred to as jitter.
For more information on MAPDV, see
About packet delay variation (PDV)
PPDV
The packet-to-packet delay variation in milliseconds, according to a calculation
model defined in RFC 3550.
For more information on PPDV, see
About packet-to-packet delay variation
Table 5-14 Video QoS - Transport results, MPEG Stats tab
Result
Description
