Instruction Manual

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A.2.3 Telchemy Video Quality Metrics
VQmon/HD provides real-time perceptual quality scores, performance statistics, and
extensive diagnostic data for monitored video streams in the form of the TVQM
™ (Telchemy
Video Quality Metrics) data set.
TVQM metrics reported by VQmon/HD fall into three main categories:
a) Perceptual Quality Metrics – including Mean Opinion Scores (MOS) for picture
quality (MOS-V), audio quality (MOS-A), and combined audio-video quality (MOSAV),
expressed in a range of 1 to 5, with 5 being best. For picture quality, both “Relative”
MOS (which does not consider the resolution of the display, frame rate, or progressive
vs. interlaced scanning) and “Absolute” MOS (which includes consideration of these
factors) are reported.
TVQM perceptual quality metrics also include an Estimated Peak Signal-to-Noise Ratio
(ESPR) in dB, and a set of metrics indicating the severity level (on scale of 010) of
several degradation factors including packet loss, jitter, codec type, etc.
b) Video Stream Metrics – including video stream description (image size, codec type,
frame rate, etc.); content and scene analysis (detail and motion level) metrics; frame
statistics indicating the number and proportion of each frame type (I, B, P, SI, and SP)
received/impaired/lost/discarded; average and maximum bandwidth for each frame
type and for the stream overall; video stream jitter and delay metrics; and interval
metrics.
c) Transport Metrics –including VSTQ (Video Service Transmission Quality), a 0-50
codec-independent score that measures the ability of the IPTV network to carry
reliable video; packet transport metrics (packets received/discarded/duplicate/out-of-
sequence, along with burst and gap statistics); packet jitter metrics including PPDV
(Packet-to-Packet Delay Variation); FEC (Forward Error Correction) and Reliable UDP
metrics; and MPEG-2 Transport Stream (ETSI TR 101 290) metrics.