OPTICOM PEVQ Service manual

Temporal indicators
Temporal
and spatial
alignment Distortion
classifi-
cation
Reference Signal
Impaired Signal Y
Cr
Cb
Perceptual
difference
(Y, Cr, Cb)
PEVQ Score
Indicators
for cause
analysis
}
time
time
Distortion
indicator
integration
OPTICOM Pro uct Line:
Vi eo
Quality
Testing
Voice
Quality
Testing
Audio
Quality
Testing
Data
Quality
Testing
PEVQ™–
Perceptual Evaluation of
Video Quality
PEVQ is an accurate, reliable and fast video
quality measure. It provides mean opinion score
(MOS) estimates of the video quality degrada-
tion occurring through a network, e.g. in mobile
and IP-based networks. PEVQ can be ideally
applied to test video telephony, video confer-
encing, video streaming, and IPTV applications.
The degraded video signal output from a net-
work is analyzed by comparison to the undis-
torted reference video signal on a perceptual
basis. Based on the approach to model the
human visual system, PEVQ can detect anom-
alies in the video signal and quantify them by a
multitude of key performance indicators ( PIs).
OPTICOM, the leading provider of signal based
perceptual measurement technology for voice,
audio and video, offers its new easy to use
PEVQ testing technology as an OEM solution.
Lab users can choose between the PEXQ soft-
ware suite and the PEVQ analyzer hardware.
PEVQ evaluates the quality of multimedia (QCIF,
CIF, VGA), SD and HD video formats based on
perceptual measurement, reliably, objectively
and fast.
PEVQ is based on the earlier PVQM technology
developed by PN Research and new develop-
ments of OPTICOM.
The algorithm can be divided up into four sepa-
rate blocks. The first block – pre-processing
stage – is responsible for the spatial and tem-
poral alignment of the reference and the
impaired signal. This process ensures that only
corresponding frames are compared to each
other.
The second block calculates the perceptual dif-
ference of the aligned signals. Perceptual
means that only those differences are taken
into account which are actually perceived by a
human viewer. Furthermore the activity of the
motion in the reference signal provides another
indicator representing the temporal information.
This indicator is important as it takes into
account that in frame series with low activity
the perception of details is much higher than in
frame series with quick motion.
The third block in the figure classifies the previ-
ously calculated indicators and detects certain
types of distortions.
Finally, in the fourth block all the appropriate
indicators according to the detected distortions
are aggregated, forming the final result - the
mean opinion score (MOS). The MOS value
describes the video quality on a range from 1
for very bad quality, to 5 for excellent quality.
Key Features:
• Accurate, reliable and
fast objective analysis of
perceived video quality
• Full reference based end-
to-end quality analysis
• Outputs MOS score
that correlates well
with subjective MOS
• Additional PIs for
detailed analysis
• Measurement of multime-
dia (QCIF, CIF, VGA), SD
and HD video quality
• Available as DLL/Library,
Windows™software and
PEVQ analyzer hardware
• Applications: IPTV,
streaming video, 3G,
video telephony
• Performance verified and
recommended for stan-
dardization by the Video
Quality Experts Group
(www.vqeg.org) 2008
Principle
PEXQ™, 3SQM™, PEAQ™, PEVQ™, PEDQ™ and the OPTICOM logo are registered trademarks of OPTICOM GmbH; PESQ™ is a registered trademark of OPTICOM
GmbH and Psytechnics Ltd.; the 'Single-sided Speech Quality Measure' and 'The Perceptual Quality Experts' are trademarks of OPTICOM GmbH.
This information may be subject to change. All other brand and product names are trademarks and/or registered trademarks
of their respective owners. All rights reserved. Copyright © 2008 OPTICOM GmbH - www.opticom.de
PEVQ is a full reference, intrusive measurement algorithm for video quality.
Its basic structure is shown in the figure below.
Voice Quality Testing
PSQM ITU-T P.861
PESQ ITU-T P.862
3SQM ITU-T P.563
ECHO
Au io Quality Testing
PEAQ ITU-T BS.1387
Vi eo Quality Testing
PEVQ
Network Quality Testing
VQmon
NEW:
VQEGapproved for
standardization

Specifications
Functionality
• Perceptual Evaluation of Video Quality-
PEVQ, with mapping to MOS scale
(1 bad, … 5 excellent quality)
• Analysis of multimedia, SD and HD video
formats
Input
• Raw YUV, AVI Files with RGB24, YUV444,
YUV422 or YUV420 data, 25 and 30 fps
• 6 to 20 seconds in length
Complexity
• PEVQ is widely optimized and is capable of
processing QCIF streams faster than real-
time on a 3GHz Pentium 4 machine.
Platforms
• Windows
• Linux
PEVQ - Perceptual Evaluation of Vi eo Quality
PEXQ™, 3SQM™, PEAQ™, PEVQ™, PEDQ™ and the OPTICOM logo are registered trademarks of OPTICOM GmbH; PESQ™ is a registered trademark of OPTICOM
GmbH and Psytechnics Ltd.; the 'Single-sided Speech Quality Measure' and 'The Perceptual Quality Experts' are trademarks of OPTICOM GmbH.
This information may be subject to change. All other brand and product names are trademarks and/or registered trademarks
of their respective owners. All rights reserved. Copyright © 2008 OPTICOM GmbH - www.opticom.de
About OPTICOM
OPTICOM GmbH is th l ad-
ing v ndor for voic , audio
and vid o quality m asur -
m nt t chnology and OEM
products for mobil and IP
bas d n twork t sting. With
PSQM, PESQ, PEAQ and
P
.563, th pion rs in p rc p-
tual quality t sting hav b n
providing by now four int rna-
tional world-class standards
for voic and audio quality
m asur m nt sinc th foun-
dation of OPTICOM as a spin-
off from Fraunhof r’s MP3
d v lopm nt t am in 1995.
Aft r th gr at succ ss with
PESQ - th Int rnational
Standard for voic quality
t sting, th xp rts from
G rmany now also sourc
PEVQ, th n w industry stan-
dard to m asur a p rc ptual
vid o quality KPI for str am-
ing, conf r ncing and m s-
saging applications.
OPTICOM’s prov n OEM t ch-
nology can b found in most
stat -of-th -art products of
l ading T&M v ndors, s
also www.pevq.org
OPTICOM GmbH is a privat ly
h ld company locat d in
Erlang n, G rmany.
Sales Contacts:
OPTICOM GmbH
Nägelsbachstraße 38
91052 Erlangen, GERMANY
Phone: [phone]
Fax: [phone]
[email protected]
www.opticom.de
North America:
Telchemy Inc.
Phone [phone]
JDSU - Acterna U.S.
Phone [phone]
Europe, Latin America,
Mi le East & Africa,
Asia Pacific, CIS Countries:
JDSU - Acterna
Germany GmbH
Phone: [phone]
Through our distributor net-
work, we are represented in
more than 80 countries. To find
your local sales office, please
contact [e-mail]
PEVQ MOS
The PEVQ MOS value lies within a range from
1 (bad) to 5 (excellent). The PEVQ MOS is based
on a multitude of perceptually motivated param-
eters.
Distortion in icators
For a more detailed analysis the perceptual
level of distortion in the luminance, chromi-
nance and temporal domain are provided.
Delay
The min, max and mean delay of each frame of
the test signal related to the reference signal,
as well as delay vs. time.
Brightness
The brightness of the reference and degraded
signal.
Contrast
The contrast of the distorted and the reference
sequence.
PSNR
To allow for a coarse analysis of distortions in
different domains the PSNR is provided for the
Y, Cb and Cr components separately.
Jerkiness
describes the smoothness of a video playback
which is often impaired by down-sampling, cod-
ing processes and perturbed transmissions.
Blur
is a distortion characterized by reduced sharp-
ness of contour edges and spatial detail.
Blockiness
is often the result of a low bit rate coding that
uses a block matching algorithm for the motion
estimation and a coarse quantization for the
image blocks.
Frame Skips an Freezes
are temporal artefacts occurring in video trans-
missions caused by e.g. overloaded networks.
Effective Frame Rate
Down-sampling of a video signal on a frame by
frame basis often results in loss of information
which often leads to the degradation of the
video signal. The effective frame rate is an
indicator quantifying the severeness of such
a process.
Temporal Activity an Spatial Complexity
Temporal activity and spatial complexity indica-
tors quantify the amount of activity/movement
and spatial detail in the video content. These
indicators are derived from ITU-T recommenda-
tion P.910.
Output
Besides the final quality score additional indica-
tors are provided at the output of the algorithm
for further cause analysis.
This approach to video quality estimation
includes the effects of both packet level impair-
ments (loss, jitter) and signal related impair-
ments such as blockiness, jerkiness, blur and
distortions caused by coding processes.
Future releases will be further optimized in
computational performance and prediction accu-
racy for high definition video.
OPTICOM’s PEVQ is one of the two top-ranked
models in the 2008 Video Quality Experts Group
(VQEG) multimedia evaluation and approved for
standardization.