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.
However, 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 Results - Video MDI
IPTV Results - Video MAP
IPTV Result Video (Page #6) -
displays the
Media Delivery Index (MDI)
results;
MDI (Media Delivery Index)
- value in a ratio
DF (Delay Factor)
- Average, Minimum and Maximum values. Also defined as cumulative IP jitter, it represents the time it
would take to drain an output buffer and
ensure good video playback.
MLR (Media Loss Rate)
- Average, Minimum and Maximum values. Also defined as the packet loss rate due to dropped
packets, bad/corrupted packets, or out-of-sequence packets.
Note: Media Delivery Index (MDI)
Defined by RFC4445 is the only standardized video quality metric available today. MDI quantifies two IP
transport impairments, namely Packet Jitter or Delay and Packet Loss. These test parameters are defined as
Media Delay Factor (MDI-DF) and Media Loss Rate (MDI-MLR). The Delay Factor (DF) indicates how long
a data stream must be buffered at its nominal bit rate to prevent packet loss. It gives a general idea of
network jitter using the DF measurement. The MDI-DF can give a measure of congestion in a network, by
showing utilization level, and detect if queuing is happening in network components, but it does not indicate
how much of this is due to video packet bunching. The Media Loss Rate (MLR) is the number of packets
lost during a 1 second period. MDI is expressed as a ratio namely; Delay Factor : Media Loss Rate, e.g.
70:15 The above ratio shows a delay factor of 70ms and 15 packets lost per second. MDI and MPEG
packet loss together provides a good indication of IP transmission and non related IP issues.
IPTV Result MAP:
The MAP table provides a summary of the stream composition and the programming present.
LX100 e-Manual D07-00-019 Rev A01
Page 32 of 44
