Tech-X Flex™
Base Unit User Guide Issue 1
5: IP and Video Testing
5-13
Intro
Wi
-F
i
10/100
Syste
m
IP/V
ide
o
S
pec
s
Original Quality
Original picture quality. This value represents the subjective quality of the video
before encoding, which is the theoretical maximum that the quality ever could be
after encoding, transport, and decoding.
Valid values are:
256
-
1280
, proportional to the 1.0 to 5.0 MOS range, scaled by a factor of 256.
For example, a value of 1242 is equivalent to a MOS of 4.85.
Coder Class
Video coder class, which describes the ability of the stream to tolerate packet
loss with respect to perceived quality. The coder class is determined by two
contributing factors:
• Codec - Some codecs, particularly older codecs, are very sensitive to packet
loss and degrade very quickly with small amounts of loss.
• Error correction and concealment - A number of loss mitigation techniques
may be employed to conceal packet loss, typically involving coordination
between the video server and client where checksum and other validation
methods allow missing data to be supplemented.
The specified value determines how heavily the analysis weights the effects of
packet loss. For example, if you specify an operation at high rates of loss, any
detected loss will have less of an effect on final quality scores. This is normally a
static setting on any given network that does not change between tests.
Valid values are:
•
A
- Stream can operate over networks with up to 20% packet loss
•
B
- Operation with up to 10% loss
•
C
- Operation with up to 5% loss
•
D
- Operation with up to 0.5% loss
Table 5-6
Video QoS test - Setup parameters
Parameter
Description
