Research On Quality ofUnderMPEG-2 VideoPacket LossShengke Qiu8/122005
Research On Quality of MPEG-2 Video Under Packet Loss Shengke Qiu 8/12 2005
IntroductionIt is crucial to be able to monitor the effects ofcompression and transmission related distortions in ordertoquantifytheusersQualityofExperience(QoE)The interest for us Blockiness Distortions (Blockiness) due to two factorscompression> transmission over networks with packet loss(our interest) What is blockiness due to packet loss (see a section ofvideofrequency)
► Introduction ▪ It is crucial to be able to monitor the effects of compression and transmission related distortions in order to quantify the users Quality of Experience (QoE) ► The interest for us —— Blockiness ▪ Distortions (Blockiness) due to two factors ➢ compression ➢ transmission over networks with packet loss ( our interest ) ▪ What is blockiness due to packet loss ( see a section of video frequency )
Comparison between two kinds of distortionsDistortionsduetocompressionDistortionsduetopacketloss
Comparison between two kinds of distortions Distortions due to compression Distortions due to packet loss
The computation of blockinessWe denote an image as x(m,n)8pixel8pixelme[1, M]ne[1,N]aid8-d,(m,n)=x(m,n+1)-x(m,n), ne[1,N]LN/8-1Zd,(i,8j)R中MUN/8-1j=lNLM/8-1NM[d,(8i, j)BN( M /8-1i=li=8pixelBh +Bframeseq2Referenceto[1]
The computation of blockiness 8 pixel 8 pixel 8 pixel 8 pixel ( , ) ( , 1) ( , ), [1, ] h d m n x m n x m n n N = + − m M [1, ] n N [1, ] ， 。 m M [1, ] We denote an image as ( , ) x m n /8 1 1 1 1 (8 , ) ( /8 1 N M v v j i B d i j N M − = = = − /8 1 1 1 1 ( ,8 ) ( /8 1 M N h h i j B d i j M N − = = = − 2 B B h v frameseq + = Reference to [1]
Two metrics weigh the quality of vedioNumframqimeanquality=E(frameseg)Numi=lNumZframeq, - meanguality)var quality = Var(frame)The characteristics of te-MetricsNoreference The higher the value is , the poorer the qualityis.Computationsinexpensive
►Two metrics weigh the quality of vedio ▪ 1. ► The characteristics of the metrics ▪ No reference ▪ The higher the value is , the poorer the quality is. ▪ Computations inexpensive 1 1 ( ) Num i i meanquality E frameseq framq Num = = = 2 1 1 var ( ) ( ) 1 Num i i quality Var frame frameq meanquality Num = = = − −