GENERATING MEANINGFUL VIDEO THUMBNAILS TO IMPROVE USER EXPERIENCE IN VIDEO APPLICATIONS

G

ENERATING

MEANINGFUL

VIDEO

THUMBNAILS

TO

IMPROVE

USER EXPERIENCE IN VIDEO APPLICATIONS

SUBMITTED IN PARTIAL FULLFILLMENT FOR THE DEGREE OF MASTER

OF SCIENCE

J

ORICK

VAN

H

EES

10894020

M

ASTER

I

NFORMATION

S

TUDIES

H

UMAN-

C

ENTERED

M

ULTIMEDIA

F

ACULTY OF

S

CIENCE

U

NIVERSITY OF

A

MSTERDAM

July 12, 2016

!

1

_Supervisor

₂

_Supervisor

Jan Zahálka

Stevan Rudinac

Generating meaningful video thumbnails to improve user

experience in video applications

Master Thesis Information Studies: Human Centered Multimedia

Jorick van Hees

Blue Billywig∗ University of Amsterdam

Graduate School of Informatics jorick.vanhees@student.uva.nl

ABSTRACT

q2 T`2b2Mi  MQp2H rv iQ T`QpB/2  pBbmH T`2pB2r Q7  pB/2Q BM i?2 7Q`K Q7 pB/2Q i?mK#MBHbX h?Bb pB/2Q i?mK#@ MBH Bb M Hi2`MiBp2 iQ i?2 biiB+ BK;2 i?mK#MBH- r?B+? Bb Km+? mb2/ BM iQ/vb BMi2`7+2b M/ `2 Q7i2M i?2 QMHv pBbmH +Hm2 7Q` i?2 mb2` iQ ;2i  b2Mb2 Q7 i?2 +QMi2Mib Q7 i?2 pB/2QX h?2 pB/2Q i?mK#MBH Bb /2bB;M2/ iQ BKT`Qp2 i?2 mb2` 2tT2`B2M+2 Q7 pB/2Q MpB;iBQM bi`m+im`2bX q2 T`2b2Mi  K2i?Q/ i?i miQKiB+HHv ;2M2`i2b i?2b2 pB/2Q i?mK#@ MBHb BM M K#B;mQmb /QKBM mbBM; +Hmbi2`BM; i2+?MB[m2b QM +QM+2Ti 72im`2b- K2i/i MHvbBb iQ ;2M2`i2 iQTB+b-M/  +QKT`BbQM iQ KMmHHv b2H2+i2/ biiB+ i?mK#MBHb BM Q`/2` iQ 2pHmi2 i?2 `2bmHibX h?2 `2bmHiBM; pB/2Q i?mK#@ MBHb `2 i2bi2/ ;BMbi biiB+ i?mK#MBHb BM  mb2` bim/v r?2`2 r2 K2bm`2 BM7Q`KiBQM M/ 2M;;2K2Mi BM mb2` 2t@ T2`B2M+2X "b2/ QM i?2 bB;MB}+Mi BKT`Qp2K2Mi i?i r2 7QmM/ `2;`/BM; BM7Q`KiBQM- r2 +QMbB/2` pB/2Q bmKK`Bb@ iBQM i2+?MB[m2b iQ T`QpB/2  bQHB/ ;`QmM/rQ`F r?2M ;2M@ 2`iBM; pB/2Q i?mK#MBHbX h?2 +?`+i2`BbiB+ BMi2Mi Q7 i?2 pB/2Q i?mK#MBH 2KT?bBb2b i?2 M22/ 7Q` Hi2`iBQMb iQ i?2b2 i2+?MB[m2b BM Q`/2` iQ BKT`Qp2 2M;;2K2Mi iQr`/b i?2 m@ /B2M+2X

Categories and Subject Descriptors

AXkXRy (oBbBQM M/ a+2M2 lM/2`biM/BM;), oB/2Q MH@ vbBbc >X8Xk (lb2` AMi2`7+2b), :`T?B+H mb2` BMi2`7+2b U:lAV

Keywords

oB/2Q i?mK#MBH ;2M2`iBQM- AMi2`7+2b

1. INTRODUCTION

h?mK#MBH BK;2b 7Q` pB/2Qb `2 mb2/ HH Qp2` i?2 r2#X h?2v `2 biiB+ `2T`2b2MiiBQMb 7Q` pB/2Qb- M/ T`QpB/2  pB@ bmH T`2pB2r Q7 i?2 pB/2Q Bib2H7X AM +QK#BMiBQM rBi?  iBiH2 M/ /2b+`BTiBQM- i?2v 7Q`K QM2 Q7 i?2 KQbi +QKKQM BMi2`@ 7+2b r?2M /2HBM; rBi?  +QHH2+iBQM Q7 pB/2QbX h?2v BM+`2b2 i?2 ++m`+v r?2M +QM/m+iBM; b2`+?2b BM pB/2Q /i#b2b-BKT`Qp2 i?2 2bi?2iB+b Q7 M Qp2`pB2r T;2- M/ +M BM+`2b2 2M;;2K2Mi r?2M TT2HBM; i?mK#MBHb `2 mb2/X

h?2 pB/2Q i?mK#MBH Bb  T`2pB2r Q7 i?2 7mHH pB/2Q BM i?2 7Q`K Q7  }p2@b2+QM/ 2t+2`Ti +QMiBMBM; MQ m/BQ- r?B+? ∗"Hm2 "BHHvrB;- *i?`BM pM _2MM2bHM ky- RkRd *s >BH@ p2`bmK- h?2 L2i?2`HM/b

+QMp2vb i?2 +QMi2Mib Q7 i?2 pB/2Q BM  KQ`2 2tT`2bbBp2 KM@ M2`X AM i?Bb rQ`F- r2 /2b+`B#2  K2i?Q/ i?i miQKiB+HHv ;2M2`i2b i?2b2 pB/2Q i?mK#MBHb mbBM; bii2@Q7@i?2@`i i2+?@ MB[m2b HBF2 +QM+2Ti 72im`2 2ti`+iBQM M/ iQTB+@/2T2M/2Mi K2i/i MHvbBbX qBi? i?2 //BiBQM Q7 biiB+ i?mK#MBHb b2H2+i2/ #v 2tT2`ib b i`BMBM; /i- r2 T`QpB/2  MQp2H rv Q7 +QMp2vBM; i?2 Tm`TQb2b Q7 i?2 biiB+ i?mK#MBH iQ i?2 pB/2Q i?mK#MBHX h?Bb rv- Qm` TT`Q+? ?b i?2 #BHBiv iQ /Dmbi iQ i?2 bT2+B}+ `2[mB`2K2Mib BM 2M;;2K2Mi M/ BM7Q`KiBQM `2;`/BM; i?2 2M/@mb2`- T`QpB/BM; /`QT@BM `2@ TH+2K2Mib 7Q` 2tBbiBM; i?mK#MBHbX

qBi? i?2 ;2M2`i2/ pB/2Q i?mK#MBHb- r2 MHvb2 i?2 27@ 72+i QM mb2` 2tT2`B2M+2 M/ /Bb+mbb i?2 mb2 Q7 pB/2Q bmKK`B@ biBQM i2+?MB[m2b BM i?2 miQKiB+ pB/2Q i?mK#MBH ;2M2`@ iBQMX q2 ?vTQi?2bBb2 i?i i?2 mb2 Q7  pB/2Q i?mK#MBH BMbi2/ Q7  biiB+ i?mK#MBH rBHH BKT`Qp2 i?2 mb2` 2tT2`B@ 2M+2 QM irQ 7`QMibX h?2 mb2` Bb KQ`2 2M;;2/ iQ ri+? i?2 7mHH pB/2Q- M/ rBHH #2 KQ`2 BM7Q`K2/ #Qmi i?2 +QMi2Mib Q7 i?2 pB/2QX 6m`i?2`KQ`2- r2 ?vTQi?2bBb2 i?i pB/2Q bmK@ K`BbiBQM i2+?MB[m2b rBHH T`QpB/2 bQHB/ ;`QmM/ iQ ;2M2`i2  i?mK#MBH- #mi `2[mB`2 /DmbiK2Mib iQ #2ii2` bmBi i?2 BM@ i2Mi Q7  pB/2Q i?mK#MBHX AM Q`/2` iQ i2bi i?2b2 ?vTQi?2bBb-irQ `2b2`+? [m2biBQMb `2 7Q`KmHi2/,

• >Qr +M r2 #mBH/  bvbi2K i?i miQKiB+HHv ;2M2`@ i2b pB/2Q i?mK#MBHb i?i ?p2  TQbBiBp2 2z2+i QM i?2 mb2`\

• >Qr /Q pB/2Q i?mK#MBHb +`2i2/ #v i?2 bvbi2K z2+i mb2`b `2;`/BM; 2M;;2K2Mi M/ BM7Q`KiBQM\ lbBM;  `2H rQ`H/ /ib2i BM M K#B;mQmb /QKBM- i?2 pB/2Q i?mK#MBH `2bmHib Q7 Qm` K2i?Q/ `2 +?HH2M;2/ BM  mb2` bm`p2v ;BMbi i?2B` biiB+ +QmMi2`T`ib- r?2`2 r2 i2bi pB/2Q T`2pB2rb rBi? M/ rBi?Qmi  i?mK#MBHX h?2b2 pB/2Q T`2pB2rb `2 i2bi2/ QM BM7Q`KiBQM M/ 2M;;2K2Mi iQr`/b i?2 mb2`X

h?2 mb2` bim/v ?B;?HB;?ib i?2 7+i i?i i?2 pB/2Q i?mK#@ MBH +M Ki+? i?2 T2`7Q`KM+2 Q7  biiB+ i?mK#MBH rBi?@ Qmi Mv T`Q#H2KbX AM //BiBQM- i?2 `2bmHib HbQ TQBMi Qmi i?i Qm` TT`Q+? Q7 mbBM;  biiB+ i?mK#MBHb b i`BMBM; /i Bb p2`v 2z2+iBp2 BM +QMp2vBM; i?2 2bb2M+2 Q7 i?2 pB/2Q-+QKT`2/ iQ  KMmHHv b2H2+i2/ biiB+ i?mK#MBH #v  T`Q@ 72bbBQMH M2rb 2/BiQ`X 6BMHHv- r2 +QM+Hm/2 i?i Qm` }M/BM;b TQb2 BMi2`2biBM; QTTQ`imMBiB2b BM BMi2`7+2 /2bB;M M/ pB/2Q MHvbBbX

1.1 Basic concepts & related work

qQ`F BM i?2 }2H/ Q7 pB/2Q bmKK`BbiBQM ?b  HQi Q7 +QK@ KQM ;`QmM/ rBi? i?2 ;2M2`iBQM Q7 pB/2Q i?mK#MBHbX "Qi? mb2 bBKBH` /i iQ 2ti`+i i?2 /2bB`2/ BM7Q`KiBQM 7`QK  pB/2Q M/ Bib K2i/i- i?2 bK2 i2+?MB[m2b BM +QKTmi2` pBbBQM Bb mb2/ iQ T`Q+2bb i?2 /i M/ i?2 2M/ `2bmHi +QmH/ #2 p2`v bBKBH`X

PM2 +QmH/ `;m2 i?i i?2 `2bmHib 7`QK pB/2Q bmKK`Bb@ iBQM +QmH/ #2 mb2/ BM bQK2 BKTH2K2MiiBQMb Q7 i?2 pB/2Q i?mK#MBHbX >Qr2p2`- i?2 mb2 +b2b BM #Qi? /QKBMb `2 /Bz2`2Mi BM i2`Kb Q7 mb2` 2M;;2K2MiX AM ;2M2`H-  bmK@ K`v i`B2b iQ ++m`i2Hv /2b+`B#2 i?2 +QMi2Mib Q7 i?2 pB/2Q-r?B+? 2HBKBMi2b i?2 M22/ iQ pB2r i?2 7mHH pB/2QX h?2 ;QH Q7 i?2 i?mK#MBH Bb iQ 2M;;2 i?2 mb2` iQ pB2r i?2 7mHH pB/2Q-Bi i`B2b iQ b?Qr Dmbi 2MQm;? iQ i`B;;2` i?2 mb2` iQ pB2r i?2 `2KBMBM; +QMi2MiX aBM+2 i?2 BKTH2K2MiiBQM b+2M`BQ M/ BMi2MiBQM Q7 i?2 pB/2Q i?mK#MBH `2 /Bz2`2Mi 7`QK pB/2Q bmKK`B2b- i?2 K2i?Q/b mb2/ iQ ;2M2`i2 pB/2Q bmKK`Bb@ iBQM `2[mB`2 Hi2`iBQMb iQ K22i i?2 bT2+B}+ /2KM/b Q7 i?2 pB/2Q i?mK#MBHX

User engagement.

lb2` 2M;;2K2Mi BM `2HiBQM iQ Ur2#V TTHB+iBQMb Bb i?2 [mHBiv Q7 2tT2`B2M+2 M/ BMi2`+iBQM Q7 i?2 mb2` rBi? M TTHB+iBQMX q2 +M /2b+`B#2 mb2` 2M;;2K2Mi b iBK2- i@ i2MiBQM M/ 2KQiBQM i?i mb2`b Tmi BMiQ i?2 TTHB+iBQM (R)-#mi i?2 r?QH2 +QM+2Ti Q7 mb2` 2M;;2K2Mi Bb 7` KQ`2 +QK@ TH2t i?M i?2b2 bT2+ibX AM M 2ti2MbBp2 bim/v iQr`/b i?2 +QM+2Ti Q7 2M;;2K2Mi BM p`BQmb }2H/b Q7 rQ`F #v PǶ"`B2M M/ hQKb (k)- 7Qm` bi;2b Q7 2M;;2K2Mi `2 /2b+`B#2/- HQM; rBi? i?2 ii`B#mi2b i?i `2 +`m+BH BM 2+? bi;2X

h?2 pB/2Q i?mK#MBH Bb KBMHv M 2bi?2iB+ 2H2K2Mi BM i?2 TTHB+iBQM Q7 pB/2Qb M/ i?2B` T`2pB2rbX b /2b+`B#2/ BM PǶ"`B2M M/ hQKb (k)- 2bi?2iB+b `2 +`m+BH BM i?2 TQBMi Q7 2M;;2K2Mi- /Bb2M;;2K2Mi M/ i?2 T2`BQ/ Q7 bmbiBM2/ 2M;;2K2MiX oB/2Q T`2pB2rb +M #2 pB2r2/ b  T`BK`v 7+iQ` BM i?2 bii2 ǵTQBMi Q7 2M;;2K2MiǶ- r?2`2 i?2 pB/2Q Bib2H7 Bb  7+iQ` BM i?2 ǵT2`BQ/ Q7 bmbiBM2/ 2M;;2K2MiǶX h?2 bim/v HBbib 7Qm` ii`B#mi2b i?i T`2b2Mi QTTQ`imMBiB2b 7Q` i?2 2M;;2K2Mi Q7 mb2`b BM i?2b2 bi;2b, 2bi?2iB+ 2H2K2Mib `2 TH2bBM; Q` ii2MiBQM ;2iiBM;- LQp2H T`2b2MiiBQM Q7 BM7Q`K@ iBQM- AMi2`2bi- M/ #2+QKBM; bBimi2/ BM i?2 dzbiQ`vǴ Q7 i?2 TTHB+iBQMX

h?2 MQp2Hiv Q7 i?2 pB/2Q i?mK#MBH +QmH/ THv M BKTQ`@ iMi `QH2 BM i?2 2M;;2K2Mi Q7 mb2`b- biiB+ i?mK#MBHb `2  +QKKQM 72im`2 BM iQ/vb BMi2`7+2b M/ pB/2Q i?mK#MBHb `2  M2r rv Q7 T`2b2MiBM; i?2 BM7Q`KiBQMX h?2 2bi?2iB+ Q7 i?2 pB/2Q i?mK#MBH p2`v Km+? /2T2M/b QM i?2 K2i?Q/ Q7 +`2iBM;  pB/2Q i?mK#MBHbX h?2 BM+HmbBQM Q7 KQpBM; BK@ ;2b BM i?2 T`2pB2r +QmH/ #2 BKTQ`iMi rBi? `2;`/b iQ i?2 ii2MiBQMX 6BMHHv- i?2 BMi2`2bi Q7 i?2 mb2` M/ i?2 ǵbiQ`vǶ Q7 i?2 TTHB+iBQM +QmH/ #2 2M?M+2/ #v b2H2+iBM; i?2 `B;?i b?Qib 7`QK i?2 pB/2Q iQ mb2 BM i?2 T`2pB2rX

Event detection.

1tBbiBM; K2i?Q/b 7Q` pB/2Q 2p2Mi /2i2+iBQM #b2/ QM i?2 h_1*oA. J2/B 1p2Mi .2i2+iBQM hbF (j) Q7i2M mb2 i?2 T`QpB/2/ i`BMBM; /iX AM Qm` TT`Q+?- MQ i`BMBM; /i Bb pBH#H2 7Q` Qm` bT2+B}+ ;QH Q7 pB/2Q i?mK#MBHbX >Qr@ 2p2`- r2 +M mb2  MmK#2` Q7 i2+?MB[m2b BM Q`/2` iQ 2ti`+i i?2 KQbi +?`+i2`BbiB+ 7`K2b 7`QK i?2 pB/2QX *Hmbi2`BM; 7`K2 p2+iQ`b Bb  i2+?MB[m2 i?i Bb mb2/ BM Q`/2` iQ }M/

`2Hi2/ T`ib BM i?2 pB/2QX *QM+2Ti 72im`2b `2 2ti`+i2/ 7`QK 7`K2b rBi?  biM/`/ 7`K2 BMi2`pH- r?B+? `2 i?2M +Hmbi2`2/ mbBM; mMbmT2`pBb2/ H;Q`Bi?Kb HBF2 E@K2Mb Q`  ?B2``+?B+H p`BMi Q7 E@K2MbX h?2b2 +Hmbi2`b +M #2 mb2/ BM pB/2Q bmKK`BbiBQMb iQ b?Qr  p`B2iv Q7 pB/2Q +QMi2Mib (9- 8)X

Video navigation.

h?2`2 `2  HQi Q7 BMi2`7+2b /2bB;M2/ iQ bbBbi ?mKMb BM MpB;iBM;  pB/2Q HB#``vX  bmKK`v #v a+?Q2zKMM 2i HX (e) /2b+`B#2b Qp2` 9y /Bz2`2Mi BMi2`7+2b i?i mb2 /Bz2`2Mi i2+?MB[m2b iQ HHQr +QMp2MB2Mi #`QrbBM; i?`Qm;?  +QHH2+iBQM Q7 pB/2QbX h?2b2 `M;2 7`QK /BbTHvBM;  F2v 7`K2 #2bi /2@ b+`B#BM; i?2 pB/2Q- Q`  +QHH2+iBQM Q7 F2v7`K2b rBi? i?2B` bBx2b `2Hi2/ iQ i?2 BKTQ`iM+2 Q7 i?2 7`K2X JQbi Q7 i?2b2 BMi2`7+2b 72im`2  bvbi2K i?i miQKiB+HHv /2i2`KBM2b r?i iQ /BbTHv QM i?2 b+`22M- iF2M BMiQ +QMbB/2`iBQM i?2 /Bz2`2Mi +QM/BiBQMb BM r?B+? i?2 bvbi2K Bb mb2/X  bim/v #v >Ƀ`bi 2i HX (d) /2b+`B#2b  mb2` bim/v iQ i?2 `2+Q;MB@ iBQM Q7 pB/2Q mbBM; /Bz2`2Mi i?mK#MBH bBx2b- MmK#2`b M/ p`BQmb KQp2K2Mi BM i?2 i?mK#MBHbX h?2 bim/v b?Qrb i?i mb2`b `2 #H2 iQ ?M/H2 KmHiBTH2 bKHH i?mK#MBHb QM KQ#BH2 /2pB+2b- 2bT2+BHHv r?2M i?2 i?mK#MBHb BM+Hm/2/ KQiBQMX aBM+2 QM2 Q7 i?2 ;QHb Q7 i?2 pB/2Q i?mK#MBH Bb iQ BKT`Qp2 i?2 MpB;iBQM Q7 mb2`b BM  M2rb K2/B r2#bBi2- pB/2Q Mp@ B;iBQM HBi2`im`2 +QmH/ 2bT2+BHHv T`Qp2 mb27mH BM i?2 /2bB;M M/ BKTH2K2MiiBQM Q7 pB/2Q i?mK#MBHb BM Qp2`pB2r T;2bX

Static thumbnail generation.

h?2 Bbbm2 Q7 pB/2Q MpB;iBQM mbBM; i?mK#MBHb ?b #22M M +iBp2 iQTB+ Q7 `2b2`+?X  kyR8 bim/v #v EBK 2i HX (3) /2b+`B#2b  K2i?Q/ Q7 miQKiB+HHv +QK#BMBM; pB/2Q 7`K2b iQ ;2M2`i2  i?mK#MBH +QMiBMBM; KQ`2 BM7Q`KiBQM i?i  bBM;H2 7`K2X MQi?2` bim/v /2b+`B#2b i?mK#MBH +M/B/i2 b2H2+iBQM mbBM; BK;2 [mHBiv 2pHmiBQM (N)X  +QK#BM@ iBQM Q7 BMi2`MH M/ 2ti2`MH MHvbBb Q7 i?2 pB/2Q +QMi2Mi iQ b2H2+i i?mK#MBHb Bb mb2/ #v  bim/v #v GBm 2i HX (Ry)X h?2 i2+?MB[m2b M/ MHvbiBQM K2i?Q/b i?i `2 72im`2/ BM i?2b2 K2i?Q/b +M TQbbB#Hv #2 Q7 mb2 r?2M 2pHmiBM; i?2 ;2M2`i2/ pB/2Q i?mK#MBHbX

JMv TT`Q+?2b iQ ;2M2`iBM; i?mK#MBHb mb2  `MF@ BM; Q7 /Bz2`2Mi 7`K2b iQ T`QTQb2  bmBi#H2 i?mK#MBH (RR-Rk- Rj)X AM biiB+ i?mK#MBH ;2M2`iBQM- i?Bb `MFBM; +M #2 mb2/ iQ b2H2+i i?2 #2bi i?mK#MBHX AM pB/2Q i?mK#MBH ;2M2`@ iBQM UQ` Qi?2` pB/2Q MpB;iBQM BMi2`7+2bV i?2 `MFBM; +M #2 mb2/ iQ +`2i2  +QKTQbBiBQM Q7 i?2 pB/2QX h?Bb +`2i2b QTTQ`imMBiB2b iQ ;2M2`i2 pB/2Q i?mK#MBHb i?i +QMbBbi Q7 /Bz2`2Mi b?Qib 7`QK i?2 Q`B;BMH pB/2QX

2. GENERATING VIDEO THUMBNAILS

h?2 KBM #Q/v Q7 i?Bb TT2` +QMbBbib Q7 i?2 /2bB;M Q7  K2i?Q/ i?i Bb #H2 iQ ;2M2`i2 pB/2Q i?mK#MBHb #b2/ QM i2timH K2i/i M/ i?2 pB/2Q Bib2H7- i`BM2/ QM biiB+ i?mK#MBHb b2H2+i2/ #v 2tT2`ibX q2 b2i  MmK#2` Q7 `2[mB`2@ K2Mib 7Q` Qm` K2i?Q/,

• h?2 ;2M2`i2/ i?mK#MBH QMHv +QMiBMb  bBM;H2 pB/2Q b2;K2Mi 2ti`+i2/ 7`QK i?2 pB/2Q- MQi  +QKTBHiBQM Q7 pB/2Q b2;K2MibX

• *QMi2Mib Q7 i?2 pB/2Q i?mK#MBH b?QmH/ #2 TT`QT`Bi2 7Q` i?2 BMi2MiBQM Q7  i?mK#MBHX

• Pm` K2i?Q/ b?QmH/ bmBi2/ 7Q` i?2 ;2M2`iBQM Q7 pB/2Q i?mK#MBHb BM M K#B;mQmb /QKBMX

h?2 TT`Q+? +M #2 /BpB/2/ BMiQ }p2 KDQ` bi;2b, 62@ im`2 2ti`+iBQM- +M/B/i2 b2H2+iBQM- +M/B/i2 2pHmiBQM M/ iQTB+@#b2/ KQ/2H i`BMBM;X AM i?2 }`bi bi;2-  MmK@ #2` Q7 KQK2Mib BM i?2 pB/2Q `2 b2H2+i2/ M/ H#2H2/ b +M@ /B/i2bX AM i?2 b2+QM/ bi;2- +M/B/i2b `2 H#2H2/ rBi?  TQbBiBp2 Q` M2;iBp2 pHm2 #b2/ QM i?2B` bBKBH`Biv iQ  i?mK#MBH b2H2+i2/ #v M 2tT2`i U`272``2/ iQ b i?2 ǵb2H2+i2/ i?mK#MBHǶVX AM i?2 i?B`/ bi;2- HH pB/2Qb BM i?2 /ib2i `2 +Hmbi2`2/ #b2/ QM iQTB+b /2`Bp2/ 7`QK i?2B` K2i/iX AM i?2 7Qm`i? M/ }MH bi;2- M aoJ Bb i`BM2/ 7Q` 2+? +Hmbi2` mbBM; i?2 H#2H2/ +M/B/i2b 7`QK 2+? pB/2Q BM i?i +Hmbi2`X

2.1 Dataset requirements

AM Q`/2` iQ ;2M2`i2  K2MBM;7mH pB/2Q i?mK#MBH- i`BM@ BM; 2tKTH2b BM i?2 7Q`K Q7 biiB+ i?mK#MBHb `2 `2[mB`2/ BM i?2 /ib2i iQ i`BM KQ/2Hb i?i +M 2pHmi2 M/ `MF pB/2Q i?mK#MBH +M/B/i2bX q2 mb2 ?mKM@b2H2+i2/ BK@ ;2b i?i `2 mb2/ b  i?mK#MBH 7Q` 2+? pB/2Q- bBM+2 i?2v +QMiBM i?2 +QM+2Tib i?i `2T`2b2Mi i?2 pB/2Q #2bi 7`QK  ?mKM T2`bT2+iBp2X MQi?2` /pMi;2 Q7 mbBM; i?2 biiB+ i?mK#MBH b 2pHmiBQM /i- Bb i?i Bi ?b i?2 bK2 Tm`@ TQb2 b i?2 pB/2Q i?mK#MBH i?i Qm` K2i?Q/ +`2i2bX aBM+2 Qm` TT`Q+? b?QmH/ #2 bmBi#H2 7Q` HH bQ`ib Q7 M2rb pB/2Qb-i?2 /ib2i Bb MQi HBKBi2/ iQ  bBM;H2 /QKBMX h?2 `2[mB`2/ bBx2 Q7 i?2 /ib2i b?QmH/ #2 `QmM/ i?2 ?mM/`2/b Q7 pB/2Qb-#b2/ QM 2`HB2` `2b2`+? BM pB/2Q bmKK`BbiBQM (R9- R8-Re) M/ i?2 7+i i?i r2 `2 +Hmbi2`BM; Qm` bKTH2b #b2/ QM iQTB+b Ub2+iBQM kX8VX

2.2 Feature extraction

62im`2b 7`QK i?2 pB/2Q `2 2ti`+i2/ 7`QK BM/BpB/mH 7`K2b rBi? R 7`K2 T2` b2+QM/ mbBM;  +QMpQHmiBQMH M2m`H M2irQ`F- i`BM2/ QM i?2 AK;2L2i /ib2i (Rd) mbBM; *z2 (R3)X h?2 `2bmHi Bb  ?B;?@H2p2H bT`b2 72im`2 `2T`2b2MiiBQM Q7 i?2 7`K2 rBi? Ryyy /BK2MbBQMb- r?B+? Bb mb2/ i?`Qm;?Qmi i?2 bvbi2K b  `2T`2b2MiiBQM Q7 i?2 7`K2X h?Bb i2+?MB[m2 Q7 2ti`+iBM; 72im`2b T`Qp2b iQ #2 p2`v 2z2+iBp2 7Q` 2p2Mi@ /2i2+iBQM (RN- ky- kR) M/ pB/2Q bmKK`BbiBQM (8- kk)X

2.3 Candidate selection

AMbi2/ Q7 2pHmiBM; HH TQbbB#H2 7`K2b BM  pB/2Q mbBM;  bHB/BM; rBM/Qr-  MmK#2` Q7 +M/B/i2b `2 b2H2+i2/ 7`QK i?2 pB/2QX h?2 b2H2+iBQM H;Q`Bi?K Bb BMbTB`2/ #v i?2 #;@Q7@ 7`;K2Mib b /2b+`B#2/ BM (9)X qQ`F BM pB/2Q bmKK`BbiBQM M/ 2p2Mi /2i2+iBQM mb2 bBKBH` +Hmbi2`BM; i2+?MB[m2b BM Q`@ /2` iQ 2bi#HBb?  b2KMiB+ bi`m+im`2 BM i?2 pB/2Q (kj- k9)X h?Bb b2KMiB+ bi`m+im`2 +M #2 miBHBb2/ iQ /Bb+Qp2` i?2 KQbi `2T`2b2MiBM; rBM/Qr 7Q` 2p2`v +Hmbi2`- r?B+? +M #2 mb2/ b +M/B/i2bX  b+?2KiB+ Qp2`pB2r Q7 i?Bb K2i?Q/ Bb b?QrM BM };m`2 RX

 +QKT`2?2MbBp2 HBbi Q7 pB/2Q i?mK#MBH +M/B/i2b Bb ;2M@ 2`i2/ mbBM;  bHB/BM; rBM/Qr Q7 8 b2+QM/b rBi? R 7TbX h?2 pB/2Q 7`K2b BM i?2 rBM/Qr `2 Kt@TQQH2/ BMiQ  p2+iQ` `2T`2b2MiiBQM i?i `2T`2b2Mib 2p2`v +QM+2Ti BM i?2 pB/2Q i?mK#MBHX AM Q`/2` iQ T`mM2 i?2 HBbi Q7 +M/B/i2b- i?2 pB/2Q i?mK#MBH Bb +QKT`2/ iQ  #;@Q7@7`;K2Mib `2T`2b2M@ iiBQM Q7 i?2 7mHH pB/2QX h?2 #;b Q7 7`;K2Mib `2 +`2i2/ rBi? i?2 72im`2b 2ti`+i2/ 7`QK HH 7`K2b- +Hmbi2`2/ mb@ BM; E@K2MbX h?2 MmK#2` E Bb +H+mHi2/ mbBM; i?2 H2M;i?

Q7 i?2 pB/2Q K =f rames

20∗fpsX h?2 bBKBH`Biv #2ir22M i?2 pB/2Q

i?mK#MBH M/ 2+? "Q6 Bb K2bm`2/ mbBM; +QbBM2 bBKBH`BivX h?2 `2bmHiBM; bBKBH`Biv p2+iQ` UrBi? E /BK2MbBQMbV Bb i?2M MQ`KHBb2/- iQ T`BQ`BiBb2 i?2 KQbi `2T`2b2MiBM; pB/2Q i?mK#@ MBH 7Q` 2+? "Q6X 6BMHHv-  `MFBM; Bb K/2 7Q` 2+? "Q6 r?2`2 i?2 iQT `2bmHi BM 2+? `MFBM; Bb b2H2+i2/ b i?mK#MBH +M/B/i2X  pBbmHBbiBQM Q7 i?Bb K2i?Q/ TTHB2/ iQ  pB/2Q +M #2 7QmM/ BM };m`2 RyX

6B;m`2 R,  b+?2KiB+ Qp2`pB2r Q7 i?2 +M/B/i2 b2H2+iBQMX

2.4 Candidate evaluation

h?2 `2bmHiBM; HBbi Q7 +M/B/i2b Bb `MF2/ #b2/ QM i?2 ?mKM@b2H2+i2/ biiB+ i?mK#MBH 7Q` i?i bT2+B}+ pB/2QX h?2 bK2 K2i?Q/ Q7 2ti`+iBM; 72im`2b 7`QK i?2 pB/2Q Bb mb2/ QM i?2 biiB+ i?mK#MBH- r?B+? `2bmHib BM  +QM+2Ti p2+iQ` i?i +M #2 +QKT`2/ iQ +QM+2Ti p2+iQ`b 2ti`+i2/ 7`QK i?2 pB/2Q 7`K2bX 6Q` 2p2`v +M/B/i2- i?2 +QbBM2 bBKBH`Biv #2ir22M i?2 +M/B/i2 p2+iQ` `2T`2b2MiiBQM Ub /2b+`B#2/ BM b2+iBQM kXjV M/ i?2 i?mK#MBH +QM+2Ti p2+iQ` Bb +H+mHi2/X  b+?2KiB+ Qp2`pB2r Q7 i?Bb T`Q+2bb Bb b?QrM BM };m`2 kX

6B;m`2 k, 1pHmiBQM i?2 ;2M2`i2/ +M/B/i2b mbBM; i?mK#@ MBHb b2H2+i2/ #v M 2/BiQ`X

aBM+2 i?2 `2bmHiBM; bBKBH`Biv pHm2b `2 p2`v /Bp2`b2 +`Qbb i?2 /ib2i-  iQT N T2`+2MiBH2 b2H2+iBQM Bb mb2/ iQ /2i2`KBM2 TQbBiBp2 U+1V M/ M2;iBp2 U−1V pHm2b r?B+? +M Hi2` #2 mb2/ iQ i`BM i?2 aoJ KQ/2HbX b b?QrM BM };m`2 j- i?2 bBKBH`Biv pHm2b #2ir22M +M/B/i2b M/ i?2 i?mK#MBH `2 ?B;?Hv B``2;mH` +`Qbb /Bz2`2Mi pB/2QbX  i?`2b?QH/ #b2/ QM  T2`+2MiBH2 Bb i?2`27Q` KQ`2 bmBi2/ iQ +`2i2  #HM+2/ i`BMBM; b2i i?i BM+Hm/2b /i 7`QK HH pB/2QbX h?2 N pHm2 Bb b2H2+i2/ i ky- bBM+2 Bi T`QpB/2b  #HM+2/ /Bbi`B#miBQM Q7 TQbBiBp2 M/ M2;iBp2 2tKTH2b mb2/ b i`BMBM; /iX

6B;m`2 j, oBbmHBbiBQM Q7 i?2 +QbBM2 bBKBH`Biv #2ir22M i?2 b2H2+i2/ i?mK#MBH M/ +M/B/i2b 7Q` KmHiBTH2 pB/2QbX

2.5 Topic clustering using metadata

b /2b+`B#2/ BM b2+iBQM kXR- i?2 pB/2Qb BM i?2 /ib2i `2 MQi HBKBi2/ iQ  bBM;H2 /QKBM M/ i?2 b2H2+i2/ i?mK#MBHb p`v BM +QMi2Mib i?`Qm;?Qmi i?2 r?QH2 /ib2iX AM Q`/2` iQ BKT`Qp2 ++m`+v M/ T`QpB/2  #2ii2` T`2/B+iBQM Q7 TQbBiBp2 pB/2Q i?mK#MBHb- i?2 /ib2i Bb +Hmbi2`2/ BMiQ bT2+B}+ iQTB+b mbBM; i?2 K2i/i pBH#H2X

aBM+2 bT2+B}+ iQTB+ +i2;Q`BbiBQM Bb MQi pBH#H2 M/ i?2 i;b pBH#H2 BM i?2 K2i/i `2 MQi /Bb+`BKBMiBp2-  i2t@ imH MHvbBb Q7 HH K2i/i Bb mb2/X h?2 iBiH2- /2b+`BTiBQM M/ i;b `2 +QM+i2Mi2/ M/  biQTHBbi Bb mb2/ iQ `2KQp2 `2;mH` rQ`/bX  #;@Q7@rQ`/b +Q`Tmb Bb 7Q`K2/ rBi? i?2 `2@ bmHiBM; /Q+mK2Mib- r?B+? Bb mb2/ iQ +`2i2  Hi2Mi .B`B+?H2i HHQ+iBQM KQ/2H rBi?  MmK#2` Q7 iQTB+b T = 25X h?Bb pHm2 7Q` T Bb +?Qb2M #2+mb2 Qm` /QKBM QMHv BM+Hm/2b M2rb `2@ Hi2/ /Q+mK2Mib- r?BH2  pHm2 Q7 Ryy Bb `2bQM#H2 7Q` i?2 r?QH2 qBFBT2/B /ib2i (k8- ke)X

qBi? i?2 G. KQ/2H-  bT`b2 p2+iQ` `2T`2b2MiiBQM Q7 i?2 pB/2Q K2i/i Bb ;2M2`i2/ r?B+? +M #2 mb2/ iQ +Hmbi2` i?2 pB/2Qb BM i?2 /ib2iX *Hmbi2`BM; Bb /QM2 mbBM; E@K2Mb rBi? M +Hmbi2`bX  H`;2` M rQmH/ K2M KQ`2 bT2+B}+ iQTB+b M/ KQ`2 ++m`i2 aoJ T`2/B+iBQMb- #mi rBHH HbQ `2/m+2 i?2 MmK#2` Q7 bKTH2b 7Q` 2+? iQTB+X q2 7QmM/ i?i i?2 B/2H pHm2 Q7 J rQmH/ #2 `QmM/ Ry- r?B+? `2bmHib BM  ;QQ/ #HM+2 #2ir22M i?2 MmK#2` Q7 bKTH2b T2` iQTB+ M/ BM2`iB Q7 i?2 +Hmbi2`bX h?2 b+Q`2b Q7 i?2 aoJ `2 pBbmHBb2/ ;BMbi /Bz2`2Mi pHm2b 7Q` J BM };m`2 8X M Qp2`pB2r Q7 i?2 iQTB+ +Hmbi2`BM; +M #2 7QmM/ BM };m`2 9X

2.6 Model training

6Q` 2+? iQTB+ +`2i2/ BM i?2 iQTB+ +Hmbi2`BM;- M aoJ Bb i`BM2/ BM Q`/2` iQ `MF M2r pB/2Q i?mK#MBH +M/B/i2bX h?2 /i mb2/ 7Q` i`BMBM; M aoJ +QMbBbib Q7 HH i?2 pB/2Qb i?i `2 +HbbB}2/ BM i?i bT2+B}+ +Hmbi2` Ub /2b+`B#2/ BM b2+iBQM kX8V- HQM; rBi? i?2 H#2Hb ;2M2`i2/ BM b2+iBQM kX9X

AM Q`/2` iQ pQB/ Qp2`}iiBM; i?2 /i- r2 mb2 i?2 bK2 T@ `K2i2` C = 10 7Q` 2+? aoJ- r?B+? `2bmHi2/ BM M p2`;2 ++m`+v Q7 yXdNX

2.7 Predicting new videos

L2r pB/2Qb rBi? `2Hi2/ i2timH K2i/i +M #2 T`Q@ +2bb2/ mbBM; Qm` K2i?Q/ iQ ;2M2`i2  pB/2Q i?mK#MBHX 6B`bi- i?2 7`K2b `2 MHvb2/ rBi? R 7Tb iQ +QM+2Ti p2+@ iQ`b b /2b+`B#2/ BM b2+iBQM kXkX h?2b2 7`K2b `2 i?2M mb2/ iQ +`2i2  HBbi Q7 +M/B/i2b b /2b+`B#2/ BM b2+iBQM kXjX h?2 i2timH K2i/i Bb +QMp2`i2/ iQ  #;@Q7@rQ`/b- r?B+? Bb i?2M +QMp2`i2/ iQ M G. p2+iQ` rBi? i?2 KQ/2H ;2M@ 2`i2/ BM kX8X h?Bb p2+iQ` +M i?2M #2 mb2/ iQ /2+B/2 QM i?2 KQ/2H iQ mb2X h?2 +QM+2Ti p2+iQ` `2T`2b2MiiBQM Q7 i?2 pB/2Q i?mK#MBH +M/B/i2b `2 i?2M TTHB2/ iQ i?2 KQ/2H Ui`BM2/ BM b2+iBQM kXeV- r?B+? +HbbB}2b i?2 p2+iQ`bX h?2 }MH `MFBM; Bb #b2/ QM i?2 b+Q`2b i?i `2 bbQ+Bi2/ rBi? i?2 +HbbB}+iBQMX

6B;m`2 8, aoJ b+Q`2b QM /Bz2`2Mi pHm2b Q7 M rBi?  #b2@ HBM2 Q7 yX8X

3. EXPERIMENTAL SETUP

h?2 h_1*oA. JmHiBK2/B 1p2Mi .2i2+iBQM i`+F T`Q@ pB/2b  MmK#2` Q7 /ib2ib i?i +M #2 mb2/ 7Q` 2p2Mi@ /2i2+iBQM i`BMBM; ibFb- r?B+? `2 Q7i2M mb2/ BM pB/2Q bmK@ K`BbiBQM (8- R8- Re)X Pi?2` T`2pBQmb i2+?MB[m2b BM pB/2Q ?B;?HB;?iBM; M/ bmKK`BbiBQM mb2 /i ;i?2`2/ 7`QK QM@ HBM2 THi7Q`Kb b uQmhm#2 M/ 6+2#QQF (kd- R9)X

h?2 /ib2i i?i Bb mb2/ BM Qm` 2tT2`BK2MiH b2imT Bb `2@ i`B2p2/ 7`QK i?2 A`Bb? QMHBM2 Tm#HBb?2` ǵGM/K`F .B;BiHǶ r?B+? Bb MQi Tm#HB+Hv pBH#H2X h?2 M2rb r2#bBi2b 7`QK i?Bb Tm#HBb?2` Tm#HBb? M2rb `iB+H2b QM  #`Q/ MmK#2` Q7 /QKBMb HBF2 rQ`H/ M2rb- bTQ`ib- #mbBM2bb- HB72 M/ HQ+H M2rbX h?2 pB/2Qb `2 Q7i2M Tm#HBb?2/ HQM;bB/2 M `iB+H2 i?i +QmH/ #2 +i2;Q`Bb2/ BM Mv /QKBMX h?2 /ib2i- ?Qr@ 2p2`- /Q2b MQi +QMiBM Mv `272`2M+2b iQ i?2 `2Hi2/ `iB+H2b Q` /QKBMbX

h?2 pB/2Qb BM i?2 /ib2i `2 ++QKTMB2/ #v K2i/i BM i?2 7Q`K Q7  iBiH2- /2b+`BTiBQM M/ M mMbT2+B}2/ MmK#2` Q7 U7`22@7Q`KV i;bX h?Bb U2/BiQ` +`2i2/V K2i/i Bb T`BK`BHv mb2/ 7Q` b2`+? 2M;BM2 QTiBKBbiBQM M/ /Q2b MQi +QMiBM Mv bi`m+im`2 Qi?2` i?M i?2 i?`22 pHm2b bT2+B}2/X aBM+2 i?2b2 pHm2b `2 +`2i2/ #v  T`Q72bbBQMH M2rb 2/BiQ`- r2 +M 9

6B;m`2 9, *Hmbi2`BM; pB/2Qb BM i?2 /ib2i #b2/ QM K2i/i mbBM; EJ2Mb +Hmbi2`BM; QM G. iQTB+ p2+iQ`bX bbmK2 i?i i?2 /i BM i?2b2 }2H/b Bb  ;QQ/ `2T`2b2MiiBQM

Q7 i?2 +QMi2MiX

b bii2/ BM b2+iBQM kXR- i?2 TT`Q+? `2[mB`2b i?mK#@ MBHb bbQ+Bi2/ rBi? i?2 pB/2Qb BM i?2 /ib2i iQ b2`p2 b TQbBiBp2 2tKTH2b 7Q` i`BMBM; Tm`TQb2bX HH pB/2Qb BM Qm` /ib2i +QMiBM  i?mK#MBH- Q7 r?B+? QMHv  TQ`iBQM Q7 i?2b2 i?mK#MBHb Bb b2H2+i2/ #v M 2tT2`i UBM Qm` +b2 M 2/BiQ` 7Q` M QMHBM2 M2rbTT2`VX h?2 `2KBMBM; i?mK#MBHb `2 m@ iQKiB+HHv ;2M2`i2/ M/ +MMQi b2`p2 b `2HB#H2 i`BMBM; 2tKTH2b- bBM+2 M 2/BiQ` ?bMǶi K/2  +QMb+BQmb /2+BbBQM #Qmi i?2 +QMi2Mib BM i?2 i?mK#MBHX h?Bb K2Mb i?i QMHv  TQ`iBQM Q7 Qm` /ib2i +M #2 mb2/ BM i?2 i`BMBM; bi;2 Q7 Qm` bvbi2KX h?2b2 biiBbiB+b +M #2 pB2r2/ BM i#H2 RX h#H2 R, Pp2`pB2r Q7 i?2 /ib2i mb2/ BM i?2 2tT2`BK2MiH b2imTX

hQiH +HBTb kRek

qBi? iBiH2 kRek

qBi? /2b+`BTiBQM RNRk

qBi? i;b ReNy

qBi? b2H2+i2/ i?mK#MBH N8e

4. USER STUDY

h?2 pB/2Q i?mK#MBHb ;2M2`i2/ #v M BKTH2K2MiiBQM Q7 i?2 K2i?Q/ /2b+`B#2/ BM b2+iBQM k ?p2 #22M i2bi2/ BM M f" mb2` bm`p2v ;BMbi  #b2HBM2 BM i?2 7Q`K Q7 biiB+ i?mK#MBHb, 8yW Q7 i?2 `2bTQM/2Mib `2+2Bp2/ i?2 bm`p2v r?B+? BM+Hm/2/ pB/2Q i?mK#MBHb- r?BH2 i?2 Qi?2` 8yW `2@ +2Bp2/  p2`bBQM rBi? biiB+ i?mK#MBHbX h?2 bm`p2v rb +QM/m+i2/ pB  +mbiQK #mBHi r2#bBi2 iQ 2Mbm`2 +QKTiB#BH@ Biv +`Qbb KmHiBTH2 /2pB+2bX

h?2 mb2` bim/v Bb +QM/m+i2/ iQ Mbr2` i?2 7QHHQrBM; [m2b@ iBQMb #Qmi i?2 mb2 Q7 i?mK#MBHb BM pB/2Q T`2pB2rb,

• ZRXR q?i Bb i?2 2z2+i Q7  i?mK#MBH QM i?2 BM7Q`@ KiBQM `2+2Bp2/ #v i?2 mb2`\

• ZRXk q?i Bb i?2 2z2+i Q7  i?mK#MBH QM i?2 2M;;2@ K2Mi Q7 i?2 mb2`\

• ZkXR q?i Bb i?2 2z2+i Q7  pB/2Q i?mK#MBH +QKT`2/ iQ  biiB+ i?mK#MBH QM i?2 BM7Q`KiBQM `2+2Bp2/ #v i?2 mb2`\

• ZkXk q?i Bb i?2 2z2+i Q7  pB/2Q i?mK#MBH +QKT`2/ iQ  biiB+ i?mK#MBH QM i?2 2M;;2K2Mi Q7 i?2 mb2`\ qBi? i?2 Mbr2`b iQ ZRXR M/ ZRXk- r2 +M +QM}`K i?i Qm` bm`p2v HB;Mb rBi? Qm` `iBQMH2 #b2/ QM `2Hi2/ rQ`F QM i?mK#MBHb /2b+`B#2/ BM RXRX q2 i?2M +M 2pHmi2 i?2 Mbr2`b iQ ZkXR M/ ZkXk M/ /2TB+i  +QM+HmbBQM QM i?2 2z2+i Q7  pB/2Q i?mK#MBH BM +QKT`BbQM iQ  biiB+ i?mK#@ MBHX

4.1 Hypothesis

h?2 7QHHQrBM; ?vTQi?2b2b +M #2 7Q`KmHi2/ 7Q` i?2 [m2b@ iBQMb bii2/ BM b2+iBQM 9,

• >RXR h?2 mb2 Q7  i?mK#MBH BM  pB/2Q T`2pB2r BM@ +`2b2b i?2 BM7Q`KiBQM `2+2Bp2/ #v i?2 mb2`X

"b2/ QM i?2 `2Hi2/ rQ`F BM b2+iBQM RXR-  pBbmH T`2pB2r BM+`2b2b i?2 ++m`+v Q7 i?2 mb2` }M/BM; `2H2pMi +QMi2MiX h?mb- r2 2tT2+i i?i i?2 //BiBQM Q7 i?2 QMHv pBbmH 2H2K2Mi BM Qm` bm`p2v U2Bi?2`  pB/2Q i?mK#MBH Q` biiB+ i?mK#MBHV ?b  TQbBiBp2 2z2+i QM i?2 BM7Q`KiBQM i?i  mb2` `2+2Bp2b 7`QK i?2 i?mK#MBHX

• >RXk h?2 mb2 Q7  i?mK#MBH BM  pB/2Q T`2pB2r BM@ +`2b2b i?2 2M;;2K2Mi Q7  mb2`X

_2b2`+? QM BMi2`7+2b M/ r2#bBi2b 7Q` QMHBM2 M2rb b?Qrb  ?B;? BM~m2M+2 Q7 BK;2b QM i?2 2M;;2K2Mi Q7 mb2`b- b /2@ b+`B#2/ BM b2+iBQM RXRX q2 2tT2+i i?i  bBKBH` BM~m2M+2 Bb pBbB#H2 BM Qm` 2tT2`BK2Mi #v i?2 BMi`Q/m+iBQM Q7 Mv i?mK#@ MBHX

• >kXR h?2 mb2 Q7  pB/2Q i?mK#MBH BM+`2b2b i?2 BM@ 7Q`KiBQM `2+2Bp2/ #v i?2 mb2` +QKT`2/ iQ i?2 mb2 Q7  biiB+ i?mK#MBHX

h?2 //BiBQM Q7 KQpBM; BK;2b iQ i?2 i?mK#MBH BM+`2b2b i?2 KQmMi Q7 `r BM7Q`KiBQM /BbTHv2/ BM i?2 T`2pB2r- bQ QM2 +QmH/ `;m2 i?i i?2 KQmMi Q7 BM7Q`KiBQM +QMp2v2/ iQ i?2 mb2` Bb HbQ BM+`2b2/X _2Hi2/ rQ`F /Bb+mbb2/ BM b2+iBQM RXR HbQ ?B;?HB;?ib M BKT`Qp2K2Mi Q7 mb2` ++m`+v BM b2`+? `2bmHib r?2M +QKT`BM; pB/2Q bmKK`B2b iQ  b2`B2b Q7 biiB+ pB/2Q 7`K2bX

• >kXk h?2 mb2 Q7  pB/2Q i?mK#MBH BM+`2b2b i?2 2M@ ;;2K2Mi Q7  mb2` +QKT`2/ iQ i?2 mb2 Q7  biiB+ i?mK#MBHX

"b2/ QM i?2 BM+`2b2/ ii2MiBQM M/ BMi2`2bi iQr`/b +2`@ iBM Bi2Kb +mb2/ #v pBbmH 2H2K2Mib b /2b+`B#2/ BM RXR- r2 ?vTQi?2bBb2 i?i i?2 //BiBQM Q7 KQiBQM BM i?2 i?mK#MBH BM+`2b2b i?2 BMi2`2bi Q7  mb2` 2p2M 7m`i?2`X

4.2 Survey setup

6Q` 2+? pB/2Q- irQ T`2pB2rb r2`2 b?QrM BM bm++2bbBp2 Q`@ /2`, h?2 }`bi T`2pB2r +QMiBM2/ QMHv  iBiH2 M/ /2b+`BTiBQM-r?BH2 i?2 b2+QM/ T`2pB2r +QMiBM2/  iBiH2- /2b+`BTiBQM M/  UbiiB+ Q` pB/2QV i?mK#MBHX M 2tKTH2 Q7 i?2 T`2pB2r rBi? i?mK#MBH Bb b?QrM BM };m`2 eX

6B;m`2 e, M 2tKTH2 Q7  pB/2Q T`2pB2rX  p2`bBQM rBi?@ Qmi i?mK#MBH Bb /BbTHv2/ QM i?2 H27i- r?BH2  p2`bBQM rBi? i?mK#MBH Bb /BbTHv2/ QM i?2 `B;?iX

7i2` 2+? T`2pB2r- irQ bii2K2Mib r2`2 K/2 #Qmi i?2 pB/2Q T`2pB2r iQ K2bm`2 i?2 2M;;2K2Mi Q7 i?2 T`iB+BTMi iQr`/b i?2 pB/2Q- M/ r2i?2` i?2 T`iB+BTMi 72Hi BM7Q`K2/ #Qmi i?2 +QMi2Mib Q7 i?2 pB/2Q Ur2 rBHH `272` iQ i?2b2 bii2@ K2Mib b U+QMi2tiV,

• A K BMi2`2bi2/ BM pB2rBM; i?2 pB/2Q U2M;;2K2MiVX • A FMQr r?i iQ 2tT2+i 7`QK i?2 pB/2Q UBM7Q`KiBp2VX "v +QKT`BM; i?2 /Bz2`2M+2 BM Mbr2`b #2ir22M i?2 p2`@ bBQM rBi? i?mK#MBH M/ rBi?Qmi i?mK#MBH- r2 `2 #H2 iQ K2bm`2 i?2 BKT+i Q7 mbBM;  i?mK#MBH BM i?2 T`2pB2rX h?Bb /Bz2`2M+2 +M i?2M #2 +QKT`2/ #2ir22M i?2 biiB+ i?mK#MBH M/ pB/2Q i?mK#MBH- HHQrBM; mb iQ MHvb2 i?2 2z2+i Q7  pB/2Q i?mK#MBHX h?Bb rv- Mv T`2+QM+2TiBQM 7`QK i?2 mb2` #Qmi +2`iBM iQTB+b Q` pB/2Qb +M #2 iF2M BMiQ ++QmMiX

h?2 pB/2Qb mb2/ BM i?Bb bm`p2v r2`2 KMmHHv TB+F2/ 7`QK i?2 /ib2i #b2/ QM MmK#2` Q7 pB2rbX 1`Hv 722/#+F QM i?2 bm`p2v b2imT `2p2H2/ i?i `M/QKHv b2H2+i2/ pB/2Qb rQmH/

#2 mMBMi2`2biBM; M/ vB2H/ MQ +?M;2 BM `2bTQMb2- `2;`/H2bb Q7 i?2 7Q`K Q7 i?2 pB/2Q T`2pB2rX h?2 /Bz2`2M+2 BM i`;2i m/B2M+2 #2ir22M i?2 /ib2i bQm`+2 M/ bm`p2v `2bTQM/2Mib rQmH/ #2 i?2 T`BK`v 2tTHMiBQMX h?2 ;2 Q7 KQbi Q7 i?2 pB/2Qb Bb  b2+QM/ 2tTHMiBQM- bBM+2 KQbi Q7 i?2 M2rb pB/2Qb `2 Qmi/i2/ i i?2 TQBMi Q7 +QM/m+iBM; i?2 bm`p2vX aiiB+ i?mK#MBHb 7Q` i?2 pB/2Qb r2`2 TB+F2/ i i?2 iBK2 Q7 Tm#@ HBb?BM; i?2 Q`B;BMH pB/2Q- r?BH2 i?2 pB/2Q i?mK#MBHb r2`2 ;2M2`i2/ mbBM; i?2 K2i?Q/ /2b+`B#2/ BM b2+iBQM kX

4.3 Responses

 iQiH Q7 8j `2bTQM/2Mib T`iB+BTi2/- Q7 r?B+? kd `2@ +2Bp2/ i?2 p2`bBQM rBi? pB/2Q i?mK#MBHb- M/ ke `2+2Bp2/ i?2 p2`bBQM rBi? biiB+ i?mK#MBHbX 1+? T`iB+BTMi `2@ +2Bp2/ T`2pB2rb 7Q`  iQiH Q7 i?`22 pB/2Qb- `2bmHiBM; BM  iQiH Q7 Rjd `2bTQMb2b- Q7 r?B+? e3 `272` iQ i?2 biiB+ i?mK#@ MBH M/ eN `272` 7Q` i?2 pB/2Q i?mK#MBHX M Qp2`pB2r Q7 i?2b2 MmK#2`b +M #2 7QmM/ BM i#H2 kX

hQiH aiiB+ oB/2Q S`iB+BTMib 8j ke kd S`2pB2r R 9d kj k9 S`2pB2r k 9e kj kj S`2pB2r j 99 kk kk hQiH Rjd e3 eN h#H2 k, _2bTQMb2 Qp2`pB2r

h?2 /Bz2`2M+2 #2ir22M i?2 2tT2+i2/ MmK#2` Q7 `2bTQMb2b U53 ∗ 3 = 159V M/ i?2 +imH MmK#2` Q7 `2bTQMb2b URjdV +M #2 2tTHBM2/ #v i?2 7+i i?i i?2 T`iB+BTMib +QmH/ BMi2``mTi i?2 bm`p2v i Mv iBK2X _2bTQMb2b r?2`2 i?2 T`@ iB+BTMi BMi2``mTi2/ i?2 bm`p2v #2ir22M  T`2pB2r rBi?Qmi  i?mK#MBH- M/  T`2pB2r rBi?  i?mK#MBH r2`2 B;MQ`2/X

4.4 Result analysis

h?2 /i Bb ;i?2`2/ 7`QK irQ i2bib- QM2 rBi? biiB+ i?mK#@ MBHb M/ QM2 rBi? pB/2Q i?mK#MBHbX h?2 `2b2`+? [m2biBQMb `2 /2HB#2`i2Hv /BpB/2/ BMiQ irQ ;`QmTbX AM i?2 }`bi ;`QmT Q7 [m2biBQMb UZRV- r2 +M i2bi Qm` bm`p2v b2imT rBi? 2bi#@ HBb?2/ rQ`F M/ 7m`i?2` BMp2biB;i2 i?2 2z2+i Q7 i?2 pB/2Q i?mK#MBH UZkVX

4.4.1 Excluding thumbnail versus including

thumb-nail

lbBM; i?2 qBH+QtQM bB;M2/@`MF i2bi 7Q` Q`/BMH- TB`2/ /i-  ?B;?Hv bB;MB}+Mi /Bz2`2M+2 Bb 7QmM/ #2ir22M T`2@ pB2rb BM+Hm/BM; i?mK#MBHb M/ 2t+Hm/BM; i?mK#MBHb `2@ ;`/BM; BM7Q`KiBQM M/ 2M;;2K2MiX h?2 S@pHm2b `2 /2@ TB+i2/ BM i#H2 jX

S@pHm2

AM7Q`KiBQM UZRXRV R.yy × Ry−R9

1M;;2K2Mi UZRXkV j.RN × Ry−Ry

h#H2 j, aB;MB}+M+2 Q7 i?2 /Bz2`2M+2 #2ir22M `2bTQMb2b QM T`2pB2rb rBi?  i?mK#MBH M/ rBi?Qmi  i?mK#MBHX

h?2 `2bTQMb2b `2p2H M Qp2`H BM+`2b2 BM 2M;;2K2Mi r?2M mbBM; i?mK#MBHbX h?2b2 `2bmHib HB;M rBi? i?2 }M/@ BM;b BM Qi?2` rQ`F /2b+`B#2/ BM RXR- M/ HHQr mb iQ 7m`i?2` BMp2biB;i2 i?2 /Bz2`2M+2b #2ir22M i?2 biiB+ i?mK#MBH M/ e

i?2 pB/2Q i?mK#MBH BM i?Bb iQTB+ BM 9X9XkX h?2 `2bTQMb2b `2 pBbmHBb2/ BM };m`2 dX Video thumbnail Excluding Including Excluding Including Static thumbnail

Strongly disagree Disagree Neutral Agree Strongly agree

Responses

I know what to expect from the video

6B;m`2 d, oBbmHBbiBQM Q7 i?2 `2bTQMb2b `2;`/BM; BM7Q`K@

iBQM QM biiB+ M/ pB/2Q i?mK#MBHb- ;`QmT2/ #v T`2b2M+2

Q7 i?2 i?mK#MBHX

h?2 bK2 qBH+QtQM bB;M2/@`MF i2bi Bb mb2/ 7Q` i?2 `2@ bTQMb2b `2;`/BM; 2M;;2K2Mi- r?2`2  ?B;?Hv bB;MB}+Mi /Bz2`2M+2 Bb 7QmM/X h?2 bK2 Tii2`Mb i?i r2`2 7QmM/ 7Q` BM7Q`KiBQM `2 pBbB#H2- M Qp2`H BM+`2b2 Bb 7QmM/ r?2M BM@ +Hm/BM; i?mK#MBHb- i?Qm;? i?2 +?M;2 Bb KQ`2 bm#iH2X h?2 `2bTQMb2b `2 pBbmHBb2/ BM };m`2 3X Video thumbnail Excluding Including Excluding Including Static thumbnail

I am interested in viewing the video

Strongly disagree Disagree Neutral Agree Strongly agree

Responses

6B;m`2 3, oBbmHBbiBQM Q7 i?2 `2bTQMb2b `2;`/BM; 2M;;2@

K2Mi QM biiB+ M/ pB/2Q i?mK#MBHb- ;`QmT2/ #v T`2b2M+2

Q7 i?2 i?mK#MBHX

4.4.2 Static thumbnail versus video thumbnail

qBi? i?2 ?B;?Hv bB;MB}+Mi /Bz2`2M+2b #2ir22M biiB+ i?mK#@ MBHb M/ pB/2Q i?mK#MBHb 7QmM/ BM 9X9XR- r2 +M 7m`i?2` BMp2biB;i2 i?2 /Bz2`2M+2b #2ir22M i?2KX q2 mb2  JMM@ q?BiM2v l i2bi QM i?2 Q`/BMH /i 7`QK i?2b2 mMTB`2/ ;`QmTbX

AM Q`/2` iQ MHvb2 i?2 `2bTQMb2b BM M Q#D2+iBp2 KM@ M2`- r2 M22/ iQ +QKT`2 i?2 /Bz2`2M+2b #2ir22M i?2 biiB+ ;`QmT M/ pB/2Q ;`QmT 7Q` T`2pB2rb 2t+Hm/BM;  i?mK#MBHX aBM+2 i?2b2 T`2pB2rb r2`2 2t+iHv i?2 bK2 KQM; i?2b2 irQ ;`QmTb- r2 ?vTQi?2bBb2 i?i i?2`2 Bb MQ bB;MB}+Mi /Bz2`2M+2 #2ir22M i?2b2 ;`QmTbX

S@pHm2 AM+Hm/BM; 1t+Hm/BM;

AM7Q`KiBQM UZkXRV yXyyye yXy9R9

1M;;2K2Mi UZkXkV yXde9R yXjNj8

h#H2 9, aB;MB}+M+2 Q7 i?2 /Bz2`2M+2b #2ir22M biiB+ i?mK#MBHb p2`bmb pB/2Q i?mK#MBHb- BM+Hm/BM; M/ 2t+Hm/@ BM; i?2 i?mK#MBHX

h?2 `2bmHib bii2/ BM i#H2 9 i2HH mb  72r i?BM;bX 6B`bi Q7 HH- i?2`2 Bb MQ bB;MB}+Mi /Bz2`2M+2 `2;`/BM; 2M@

;;2K2Mi #2ir22M i?2 ;`QmTb- BM+Hm/BM; Q` 2t+Hm/BM; i?2 i?mK#MBHX _2;`/BM; BM7Q`KiBQM-  ?B;?Hv bB;MB}+Mi

/Bz2`2M+2 rb 7QmM/ r?2M  i?mK#MBH rb BM+Hm/2/- M/

 bB;MB}+Mi /Bz2`2M+2 rb 7QmM/ r?2M i?2 i?mK#MBH rb 2t+Hm/2/X

q?BH2 i?2`2 Bb  ?B;?Hv bB;MB}+Mi /Bz2`2M+2 #2ir22M biiB+ i?mK#MBHb M/ pB/2Q i?mK#MBHb `2;`/BM; BM7Q`KiBQM- r2 +MMQi /B`2+iHv /`r Mv +QM+HmbBQMb- bBM+2  bB;MB}+Mi /Bz2`2M+2 rb HbQ 7QmM/ #2ir22M i?2b2 ;`QmTb r?2M i?2 i?mK#MBH rb #b2MiX h?Bb K2Mb i?i i?2 ?vTQi?2bBb bii@ BM; i?i i?2`2 Bb MQ bB;MB}+Mi /Bz2`2M+2 #2ir22M i?2 irQ ;`QmTb r?2M 2t+Hm/BM; i?2 i?mK#MBH Bb `2D2+i2/- M/ M BM@ /2Ti? MHvbBb Bb `2[mB`2/ iQ ;BM Mv K2MBM;7mH BMbB;?ib #Qmi i?2 2z2+ib Q7 i?2 pB/2Q i?mK#MBHX

aBM+2 i?2 GBF2`i `2bTQMb2b `2 +i2;Q`Bb2/ b Q`/BMH /i-r2 +MMQi +H+mHi2 i?2 /Bz2`2M+2b Q` K2M pHm2b #2i/i-r22M i?2b2 ;`QmTbX AMbi2/- i?2 `2bTQMb2b `2 +i2;Q`Bb2/ BMiQ }p2 /Bz2`2Mi ;`QmTb #v i?2 `2bTQMb2 QM i?2 T`2pB2r rBi?@ Qmi  i?mK#MBHX h?Bb rv- r2 +M MHvb2 i?2 2z2+i Q7  i?mK#MBH r?BH2 Mv BMBiBH `2bTQMb2 QM  iQTB+ Bb iF2M BMiQ ++QmMiX  /2iBH2/ pBbmHBbiBQM Q7 i?Bb /i Bb b?QrM BM N- r?BH2 i?2 mM+i2;Q`Bb2/ `2bTQMb2b `2 b?QrM BM };m`2 d UbiiB+ i?mK#MBH, BM+Hm/BM; @ pB/2Q i?mK#MBH, BM+Hm/BM;VX

People who disagreed

People who were neutral

People who agreed

People who strongly agreed

Static Video Static Video Static Video Static Video Static Video

People who strongly disagreed I know what to expect from the video

Strongly disagree Disagree Neutral Agree Strongly agree

Responses

6B;m`2 N, 1z2+i Q7 biiB+ i?mK#MBHb p2`bmb pB/2Q i?mK#@ MBHb- `2;`/BM; BM7Q`KiBQM- +i2;Q`Bb2/ #v `2bTQMb2 QM i?2 T`2pB2r rBi?Qmi  i?mK#MBHX _2bTQMb2b i?i HB;M rBi? i?2 BMBiBH `2bTQMb2 `2 K`F2/ rBi?  r?Bi2 BM/B+iQ` iQ ?B;?HB;?i i?2 #b2HBM2 7Q` 2+? +i2;Q`vX

AM i?2 ǵbi`QM;Hv /Bb;`22Ƕ +i2;Q`v- KQ`2 i?M ?H7 Q7 i?2 `2bTQM/2Mib b?B7i2/ iQ  TQbBiBp2 Mbr2` r?2M i?2v `2+2Bp2/  T`2pB2r rBi? pB/2Q i?mK#MBHX h?2 bK2 b?B7i Bb HbQ pBbB#H2 BM i?2 ǵ/Bb;`22Ƕ +i2;Q`v- #Qi? +i2;Q`B2b b?Qr  `2@ /m+iBQM BM i?2 KQmMi Q7 M2;iBp2 `2bTQMb2bX GQQFBM; i i?2 M2mi`H M/ TQbBiBp2 `2bTQMb2b-  +H2` +QMi`bi Bb TT`2Mi BM i?2 KQmMi Q7 ǵM2mi`HǶ M/ ǵbi`QM;Hv ;`22Ƕ `2bTQMb2bX h?Bb BM+`2b2 b?Qrb i?i i?2 TQbBiBp2 2z2+i Q7  i?mK#MBH Bb KTHB}2/ rBi? i?2 mb2 Q7  pB/2Q p`BMiX

AM i?2 ǵM2mi`HǶ +i2;Q`v-  TQbBiBp2 +?M;2 BM `2bTQMb2 Bb +H2`Hv pBbB#H2 BM #Qi? biiB+ M/ pB/2Q i?mK#MBHbX ;BM-r2 b22 i?2 KTHB}2/ TQbBiBp2 2z2+i BM i?2 ǵbi`QM;Hv ;`22Ƕ `2@

6B;m`2 Ry, M 2tKTH2 Q7 i?2 #; Q7 7`;K2Mi +Hmbi2`BM;X h?2 +QHQm`2/ #`b QM i?2 iQT BM/B+i2 r?i 7`K2b `2 TH+2/ BM r?B+? +Hmbi2`X h?2 7`K2b #2HQr `2 i?2 b2H2+i2/ +M/B/i2b 7`QK 2+? iQTB+X

bTQMb2b 7Q` pB/2Q i?mK#MBHbX h?2 ǵ;`22Ƕ +i2;Q`v b?Qrb  bBKBH` i`2M/- Hi?Qm;? i?2 i?2 Qp2`HH TQbBiBp2 +?M;2 Bb H2bb MQiB+2#H2X h?2 MmK#2` Q7 `2bTQMb2b BM i?2 +i2;Q`v ǵT2QTH2 r?Q bi`QM;Hv ;`22/Ƕ Bb iQQ HBKBi2/ iQ /`r Mv +QM+HmbBQMb U#Qi? i?mK#MBH p`BMib +QMiBM2/ QMHv  bBM;H2 `2bTQMb2 7Q` ǵbi`QM;Hv ;`22ǶV- #mi Bb BM+Hm/2/ BM i?2 pBbmHBbiBQM 7Q` i?2 bF2 Q7 +QKTH2i2M2bbX

q2 +M +QM+Hm/2 i?i i?2 mb2 Q7  pB/2Q i?mK#MBH KTHB@ }2b i?2 TQbBiBp2 2z2+i +mb2/ #v i?2 mb2 Q7  i?mK#MBH BM `2;`/ iQ i?2 BM7Q`KiBQM i?i  mb2` Q#iBMb 7`QK  pB/2Q T`2pB2rX q?BH2 Qm` `2bTQMb2b b?Qr  ?BMi Q7 i?2 bK2 2z2+i QM i?2 2M;;2K2Mi U};m`2 3- r2 `2 mM#H2 iQ /`r Mv +QM@ +HmbBQMb bBM+2 i?2v `2 MQi bB;MB}+MiHv /Bz2`2MiX qBi? M BM@/2Ti? bim/v +QMiBMBM; KQ`2 +QMi`QHH2/ p`B#H2b-  H`;2` bKTH2 bBx2 M/  `2H@rQ`H/ 2MpB`QMK2Mi-  #2ii2` mM/2`@ biM/BM; Q7 i?2 2z2+i QM 2M;;2K2Mi +M #2 /2p2HQT2/X

5. CONCLUSION

AM i?Bb TT2`- r2 +QM+Hm/2 i?i Bi Bb TQbbB#H2 iQ miQKi@ B+HHv ;2M2`i2 pB/2Q i?mK#MBHb i?i ?p2  TQbBiBp2 2z2+i QM mb2`b +QKT`2/ iQ biiB+ i?mK#MBHb r?B+? `2 +QKKQMHv mb2/ iQ/vX "b2/ QM i?2 `2bmHib 7`QK Qm` mb2` bim/v- r2 +QM+Hm/2 i?i i?2 BKTH2K2MiiBQM Q7 i?2 i2+?MB[m2b 7`QK i?2 }2H/ Q7 pB/2Q bmKK`BbiBQM THv  +`m+BH T`i BM i?2 BK@ T`Qp2/ BM7Q`KiBQM i?i mb2`b 2tT2`B2M+2/X q2 #2HB2p2 i?i Qm` K2i?Q/ Q7 +M/B/i2 b2H2+iBQM `2bmHib BM  +QM+2TimHHv /Bp2`b2 b2i +M/B/i2b- r?B+? THv M BKTQ`iMi `QH2 BM i?2 BKT`Qp2K2Mi Q7 BM7Q`KiBQMX

lb2` 2M;;2K2Mi Bb  ?B;?Hv +QKTH2t iQTB+ r?2`2 KMv p`B#H2b `2 i THv BM +QKTH2t bBimiBQMbX Hi?Qm;? Qm` `2bmHib /Q MQi /B`2+iHv b?Qr  bB;MB}+Mi /Bz2`2M+2 #2ir22M pB/2Q i?mK#MBHb M/ biiB+ i?mK#MBHb- r2 ?p2 `2bQMb iQ #2HB2p2 i?i i?2 pB/2Q i?mK#MBH rBHH z2+i mb2` 2M;;2@ K2Mi r?2M M TT`Q+? Bb mb2/ i?i #2ii2` }ib i?2 bT2+B}+ BMi2Mi M/ Tm`TQb2 Q7 i?2 pB/2Q i?mK#MBHX Pm` K2i?Q/ Q7 2ti`+iBM; pB/2Q i?mK#MBHb Bb H`;2Hv #b2/ QM i2+?MB[m2b mb2/ BM pB/2Q bmKK`BbiBQM- r?2`2 i?2 T`BK`v +QM+2`M Bb iQ 2ti`+i BM7Q`KiBQM BMbi2/ Q7 BKT`QpBM; mb2` 2M;;2@ K2MiX lbBM;  i?mK#MBH b2H2+i2/ #v M 2tT2`i b 2pHmiBQM /i Bb  bi2T BM i?2 `B;?i /B`2+iBQM- M/ r2 bm;;2bi i?i H@ i2`iBQMb HBF2 i?2b2 iQ pB/2Q bmKK`v i2+?MB[m2b rBHH ;`2iHv BKT`Qp2 i?2 2M;;2K2Mi Q7 i?2 pB/2Q i?mK#MBHbX

L2r BMi2`7+2b i?i 7+BHBii2 pB/2Q i?mK#MBH b2H2+iBQM 7Q` 2/BiQ`b rBHH HHQr mb iQ 7m`i?2` MHvb2 i?2 +?QB+2b K/2 7Q` bT2+B}+ pB/2Q i?mK#MBHb- r?B+? +QmH/ H2/ iQ M2r BM@ bB;?ib M/ HHQr mb iQ /Dmbi Qm` K2i?Q/b Q7 b2H2+iBQM M/ 2pHmiBQMX h?2 2z2+ib Q7 H`;2 b+H2- `2H@rQ`H/ BKTH2K2M@

iiBQMb Q7 pB/2Q i?mK#MBHb +QmH/ HbQ #2 miBHBb2/ iQ ;BM M2r BMbB;?ib BM i?2 #2?pBQm` Q7 mb2`b rBi? i?Bb M2r BMi2`@ 7+2 2H2K2MiX 6BMHHv- r2 +QM+Hm/2 i?i i?2 T`QKBbBM; 2z2+ib Q7 pB/2Q i?mK#MBHb b?QmH/ #2 miBHBb2/ BM i?2 TTHB+iBQM Q7 T`2pB2rb 7Q` pB/2Qb BM Q`/2` iQ BKT`Qp2 mb2` 2tT2`B2M+2X

6. ACKNOWLEDGEMENTS

aT2+BH i?MFb iQ CM w?€HF 7Q` i?2 2t+2TiBQMH bmT2`pB@ bBQM QM i?Bb Kbi2` i?2bBbX >Bb BMbB;?ib M/ FMQrH2/;2 BM i?2 }2H/ Q7 KmHiBK2/B MHvbBb T`QpB/2/ +`m+BH H2/b iQ p`B@ Qmb i2+?MB[m2b M/ K2i?Q/b i?i r2`2 mb2/X q2 rQmH/ HbQ HBF2 iQ i?MF i?2 T2QTH2 i GM/K`F .B;BiH- r?Q T`QpB/2/ mb rBi? i?2 BMBiBH B/2 Q7 pB/2Q i?mK#MBHb M/ HHQr2/ mb iQ mb2 i?2B` /i 7Q` 2tT2`BK2MiiBQMX 6BMHHv- i?2 T2QTH2 i "Hm2 "BHHvrB; `2 i?MF2/ 7Q` i?2B` bmTTQ`i M/ ;2M2`H FMQrH2/;2 `2;`/BM; UQMHBM2V pB/2QX

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