IPTV Result Video (Page #4) -
displays the
Quality of Service (QOS)
results;
PCR Clock
- Presence of 27MHz Program Clock Reference
PCR Jitter
- PCR deviation in (ms)
MPEG Packet Loss
- continuity error (%)
Latency
- the time to complete a program change measured in milliseconds (ms)
IPTV Video Stream QOS & PCR
IPTV and Program Clock Reference (PCR)
MPEG TS usually contain a built-in timing packet known
as the Program Clock Reference (PCR).
Recovering the 27 MHz clock at the decoder end of the
transmission system is necessary to re-create the video
signal.
PCR values need to be correct at the signal origin and
should not be distorted along the transmission path to a
point where decoding the compressed signal becomes
problematic.
Measuring the interval between the arrival of PCR
values, the accuracy of the expected values and also
the jitter accumulated on those PCR values transmitted
is necessary to assure that streams can be decoded.
PCR jitter is a good indication of timing distortions due
to poor encoding. Excessive PCR jitter results in visual
impairments such as frame freezes, color loss and
pixelization.
The amount of PCR jitter that is considered excessive
varies, and depends on various factors including STB
buffer sizes and software architecture - in today’s
packetized video networks, PCR jitter should not
exceed 10 ms.
If PCR jitter is not constant, then a momentary problem
from inserting local programming may be the cause.
IPTV Result Video (Page #5) -
displays the
Transport
results;
MPEG Packet Loss
Packets expected
IPTV Video Transport Results
MX100/120 e-Manual D07-00-004 Rev A04
Page 96 of 115
