EXFO EXpert IPTV Test Tools (FTB-200v2) - Manual (Page 51)

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A.1.1.2 Impact of Packet Loss on Specific Video Codecs
As shown in Figure 2‐3, a simple non‐robust video stream can be severely degraded
with even low levels of packet loss due to the error propagation effects described above.
Peak Signal‐to‐Noise Ratio (PSNR) is an objective measurement of video service quality
comparing the maximum power of the video signal to the power of corrupting noise affecting
the signal. Generally, a PSNR of under 20dB is regarded as unwatchable, and this level is
reached for MPEG video with a loss rate under 1 percent.
Figure 2‐3.
Estimated PSNR
for Three
Common Codecs
Error mitigation algorithms are being increasingly applied to help to compensate for packet
loss [11][12]. Methods include:
Forward Error Correction (FEC) ‐ redundancy is applied to the data stream to allow some
proportion of lost or errored packets to be replaced