phan loai nhac

8/7/2019 Phan loai nhac

1/51

PHN LOI NHC THEOTH LOI

Nhm thc hin:

Trn Bnh ng [email protected] Vn Chnh [email protected] Nguyn Khnh Duy [email protected] Nguyn Dng [email protected]

TP. H Ch Minh - 2011


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LI NI UTrong nhng nm gn y, cng vi s bng n cng ngh thng tin v cc nhdng nhc nn ra i, u ny lm cho vic s hu nhng bi nhc tr nn d dnghn bao gi ht. Ko theo s gia tng nhu cu nhu cu su tp nhc s mic nhn hay t chc.

Vi s lng ln cc bi nhc c su tm c th vic phn nhm cc binhc d dng qun l l mt nhu cu tt yu. Tuy nhin do vic su tm nhcc th tin hnh t nhiu ngun, vi nhiu ngun cht lng m thanh khc nhau,cng nh thng tin v tng bi nhc ti v cng c mc chnh xc khc nhau,nn vic phn loi cc bi nhc ch da trn cc thng tin ghi trn tp tin lu trcn gp nhiu hn ch. Thay v ch da vo cc thng tin c sn, ngi su tm c

th t nghe li tng bi nhc ri t phn loi chng, tuy nhin vi mt s lng s cc bi nhc th vic ny l khng kh thi. iu ny l ny sinh nhu cut ng phn loi nhc trong cc h thng lu tr m nhc.

Cc h thng phn loi nhc t ng l rt cn thit, n h tr hoc thay thcon ngi trong vic su tp nhc, truy tm thng tin nhc trn Internet,... Bncnh , vic phn loi nhc t ng cung cp c s khoa hc cho vic phn tchcc tn hiu m nhc da vo ni dung.

Trong khun kh ca bi bo co ny, chng ti ch i su vo vic phn loinhc theo th loi.

D c nhiu c gng, nhng ti khng khi trnh c sai xt, nhmchng ti mong nhn c s ph bnh v gp ca thy c v cc bn.


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Mc lc

1 Lch s v h thng x l m thanh 5

I C s l thuyt 7

2 m thanh v s ha m thanh 82.1 m thanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.1.1 Ngun gc ca m v cm gic v m . . . . . . . . . . . . . 82.1.2 Nhng c tnh ca sng m . . . . . . . . . . . . . . . . . . 9

2.2 S ha m thanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3 Tng quan v m nhc 15

3.1 Nt nhc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153.2 Bt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4 Bin i Fourier 194.1 Bin i Fourier ri rc . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.1.1 nh ngha . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.1.2 Bin i Fourier ngc . . . . . . . . . . . . . . . . . . . . . . 204.1.3 Cc tnh cht . . . . . . . . . . . . . . . . . . . . . . . . . . . 214.1.4 Fast Fourier Transform . . . . . . . . . . . . . . . . . . . . . . 21

4.2 Bin i STFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244.3 Nhng hn ch ca FT v STFT . . . . . . . . . . . . . . . . . . . . 25

4.3.1 Hn ch ca FT . . . . . . . . . . . . . . . . . . . . . . . . . . 254.3.2 Hn ch ca STFT . . . . . . . . . . . . . . . . . . . . . . . . 25

5 Phn lp K - Nearest Neighbor 265.1 Khai khong d liu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.2 Phn lp l g? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.3 Phn lp k - Nearest Neighbor . . . . . . . . . . . . . . . . . . . . . 27

5.3.1 Phn lp 1 - Nearest Neighbor . . . . . . . . . . . . . . . . . 27

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5.3.2 Phn lp k - Nearest Neighbor . . . . . . . . . . . . . . . . . 275.3.3 u im, khuyt im . . . . . . . . . . . . . . . . . . . . . . 29

II Bi ton phn loi nhc theo th loi 31

6 Gii thiu bi ton 326.1 Nhu cu thc t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326.2 Gii thiu bi ton phn loi nhc theo th loi . . . . . . . . . . . 326.3 M hnh tng qut h thng phn nhc theo th loi . . . . . . . . . 34

7 Thut gii 357.1 Rt trch c trng . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.2 Cc c trng lin quan n b cc m sc (Timbral Texture Features) 367.3 Ci tin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387.4 Khong cch gia hai mu . . . . . . . . . . . . . . . . . . . . . . . . 397.5 Hun luyn v nhn dng . . . . . . . . . . . . . . . . . . . . . . . . 40

8 Thc nghim, kt qu v nhn xt 418.1 Kho mu thc nghim . . . . . . . . . . . . . . . . . . . . . . . . . . 418.2 prjMusicalClassification . . . . . . . . . . . . . . . . . . . . . . . . . . 42

8.2.1 Th nghim vi 10 th loi . . . . . . . . . . . . . . . . . . . 428.2.2 Th nghim vi 4 th loi nh trong lun vn ban u . . . 428.2.3 Th nghim vi 4 th loi tt nht . . . . . . . . . . . . . . . 43

8.3 Hnh nh chng trnh thc nghim . . . . . . . . . . . . . . . . . . 458.4 Kt lun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498.5 Hn ch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498.6 Hng pht trin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

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Danh sch hnh v

2.1 th dao ng ca cc m pht ra t m thoa, ghita . . . . . . . 92.2 th dao ng ca cc m pht ra khi g tm kim loi . . . . . . 102.3 Sng m thanh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.4 Giai on ly mu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.5 phn gii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.1 Chu trnh cc lp nt . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.2 M hnh biu din vng bt . . . . . . . . . . . . . . . . . . . . . 173.3 M hnh biu din cc mc bn m trong 1 bt . . . . . . . . . . 173.4 Khong cch gia cc pitch class tng ng vi t l tn s . . . . . 18

5.1 Phng php phn loi 1 - Nearest Neighbor . . . . . . . . . . . . . 285.2 Phng php phn loi k - Nearest Neighbor . . . . . . . . . . . . . 29

6.1 S xc nh th loi nhc t tn hiu audio. . . . . . . . . . . . . 336.2 M hnh phn loi nhc tng qut. . . . . . . . . . . . . . . . . . . . 34

7.1 S mt vector c trng t mt tn hiu nhc. . . . . . . . . . . 357.2 S xc nh cc c trng lin quan b cc m sc. . . . . . . . 36

8.1 Biu tng quan chnh xc phn loi 10 th loi . . . . . . . . 438.2 Biu tng quan chnh xc phn loi 4 th loi . . . . . . . . 448.3 Biu tng quan chnh xc phn loi 4 th loi . . . . . . . . 458.4 Trch xut gi tr cc c trng . . . . . . . . . . . . . . . . . . . . . 45

8.5 Phn loi vi 4 th loi . . . . . . . . . . . . . . . . . . . . . . . . . . 468.6 Phn loi vi 10 th loi (1) . . . . . . . . . . . . . . . . . . . . . . . 478.7 Phn loi vi 10 th loi (2) . . . . . . . . . . . . . . . . . . . . . . . 48

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Chng 1

Lch s v h thng x lm thanh

X l m thanh c nh ngha ngun gc c s dng trong gii hcthut ch n cc vn lin quan n k thut tnh ton da vo cu to cam nhc. N bao hm nhng l thuyt v ng dng mi hay k thut tn titrong m nhc nh tng hp m thanh, x l tnh hiu s, thit k m thanh,truyn m tnh, vang... Phm vi ca tnh ton m nhc c th tnh l ngungc ca nhc in t (Nhc s), nhng th nghim ban u v sng to vi nhcdng c in t trong th k 20. Gn y, vi s pht trin ca my tnh c nhn

v s pht trin ca cc phng thu ti nh, tnh ton m nhc i lc cn c sdng ch n mi th m nhc c to s dng k thut tnh ton.Rt nhiu vic trong x l m thanh ko mi quan h gia m nhc v ton

hc li gn nhau. My tnh u tin trn th gii chi nhc l CSIRAC, n cthit k v xy dng bi Trevor Pearcey v Maston Beard. Nh ton hc GeoffHill lp trnh CSIRAC c th chi c cc giai iu thng dng ca uthp k nhng nm 1950. Trong ln cng b n vo nm 1951 n chi bn nhcColonel Bogey March, ng tic l hin khng c bn thu no c bit n. Tuynhin, CSIRAC ch chi theo nhng chun t trc v n khng th c s dng m rng c th hiu v m nhc hay cu to ca nhc bi nhc m n chc.Mt bn thu c hn c bit n ca my tnh chi nhc c chi bi my tnhmang tn Ferranti Mark 1, y l mt phin bn thng mi ca Baby Machinet i hc Manchester trong ma thu nm 1951. Chng trnh nhc c vitbi Christopher Strachey. Trong mt phin thu m ca BBC, c my c iukhin c th chi c cc giai iu : "Baa Baa Black Sheep", "Baa Baa BlackSheep", "God Save the King" v mt phn ca "In the Mood".

S trng thnh hn na vo nhng nm 1950 pht trin c ngun gcca m thanh k thut s bi my tnh, vi nhng gii thut chng trnh vt xa

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vic ch l hc vt ri pht li. Max Mathews ca Bell Laboratories pht trinchng trnh MUSIC I c nh hng ln n sau ny, hn na s thng dng canhc my tnh xuyn sut cc ti liu khoa hc vo nm 1962. Trong nhng con

ngi u tin trong , mt nhc s tn l Lejaren Hiller v Leonard Isaacson lm vic v xy dng mt lot cc gii thut x l m nhc t nm 1956-1959,xut hin ln u vo nm 1957 vi tn Illiac Suite (Tm dch l H Illiac) chochui b t.

m nhc my tnh s khai c trng khng th chy thi gian thc. Chngtrnh cn chy vi gi, vi ngy vi nhng my tnh hng triu la c th tora vi pht nhc, rt xa x. Vic John Chowning lm nn sng FM t nhngnm 1960 n nhng nm 1970 v s ra i ca nhng con chip in t, nhngcon chip nh gi r, m ra cch ca x l thi gian thc cho nhc my tnh.

u nhng nm 1990, hiu sut ca nhng b vi x l tin ti mc to ra m nhcmy tnh thi gian thc bng vic s dng chng trnh vi cc thut ton l khthi.

Truy vn thng tin nhc (Music Information Retrieval - MIR) l mt nhnhnh ca x l m thanh, MIR lin quan n vic qun l th vin nhc s. n baogm nhiu vn nh m vn cc vn nghin cu nh sau :

Phn loi, m hnh ha m nhc.

Phng php hnh thc v lu tr m nhc. Phn mm truy vn thng tin m nhc.

Giao din tng tc gia con ngi vi my tnh.

Cho my tnh c th "cm th" c m nhc.

Phn tch v ti hin li tri thc.

Lu tr m nhc, th vin nhc k thut s.

Nhn ra s hu ng ca nhc. Cc vn n x hi v kinh t vi m nhc.

tng ban u v k thut truy vn thng tin m nhc xut hin vo nhngnm 1966. Tuy nhin vn ch tht s c tm hiu t m gn y khi khi bngn s thch su tm nhc qua mng vi hnh thc nhc in t, mi th cn phttrin nhanh hn na khi cc nh dng nhc nn ra i nh mp3, cc dch v chias m nhc nh Napster ra i, cao hn na gc nhn v nhn dng m nhc, vicny s gip gim thiu chi ph v lu tr m nhc cng nh bng thng

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Phn IC s l thuyt

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Chng 2

m thanh v s ha mthanh

2.1 m thanh

2.1.1 Ngun gc ca m v cm gic v mNh chng ta bit, cc vt pht ra m u dao ng v ta gi l cc vt

l ngun m. V d nh dy n b bt, mt trng b g,...u dao ng v phtra m.

Vt dao ng lm cho lp khng kh bn cnh ln lt b nn ri b dn.Khng kh b nn hay b dn th lm xut hin lc n hi khin cho dao ng c truyn cho cc phn t khng kh xa hn. Dao ng c truyn i trongkhng kh, to thnh sng gi l sng m c cng tn s vi ngun m. Sng ml sng dc.

Sng m truyn qua khng kh lt vo tai ta gp mng nh, tc dng ln mngnh mt p sut bin thin, lm cho mng nh dao ng. Dao ng ca mng nhli c truyn n u cc dy thn kinh thnh gic lm cho ta c cm gic vm thanh (gi tt l m). Nh vy cm gic v m ph thuc vo ngun m v

tai ngi nghe. Tai con ngi ch c th cm nhn c nhng sng m c tn strong khong 16 Hz n 20 000 Hz. Nhng m c tn s cao hn 20 000 Hz gi lsiu m v nhng m c tn s nh hn 16 Hz gi l h m.

Sng m c th truyn i trong tt c cc mi trng n hi (cht kh, chtrn, cht lng) v khng truyn c qua chn khng. Vn tc truyn m phthuc vo tnh n hi v mt ca mi trng. Ni chung, vn tc truyn mtrong cht rn ln hn trong cht lng, v trong cht lng ln hn trong cht kh.

Trong cht ch v cht lng, sng m l sng dc v trong cc cht ny lc nhi ch xut hin khi c bin dng nn, dn. Trong cht rn, sng m c th lsng ngang hoc sng dc v lc n hi xut hin c thi c bin dng lch v bin

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dng nn, dn.

2.1.2 Nhng c tnh ca sng mNhc m v tp m

Hnh 2.1: th dao ng ca cc m pht ra t m thoa, ghita

Hnh 2.1 cho ta th ca dao ng phy ra t cc nhc c m ta quan stc trn mn hnh ca dao ng k t in t. Hnh 2.2 l th hnh ca daong ca mt ting g mnh trn tm kim loi. Ta nhn thy m do cc nhc cpht ra th nghe m i, d chu v th dao ng ca chng c c im chungl nhng ng cong tun hon c tn s xc nh. Chng c gi l nhc m.Cn ting g tm kim loi nghe chi tai, gy cm gic kh chu, th ca chngl nhng ng cong khng tun hon, khng c tn s xc nh. Chng c gil tp m.

cao ca m

Ta bit trong m nhc, cc nt nhc , r, mi, pha, son, la, si ng vi cc

m c cao tng dn. V d, m ng vi nt son thp hn m ng vi nt la,hoc m ng vi nt la cao hn m ng vi nt son.Nu a cc tn hiu m ny vo dao ng k in t th ta thy m cao (cn

gi l m bng) c tn s ln hn m thp (cn gi l m trm).Biu thc dng tnh cao l

p = 69 + 13log2f

440

vi f l tn s ca m thanh.

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Hnh 2.2: th dao ng ca cc m pht ra khi g tm kim loi

m sc

Khi ta nghe ha nhc, ba nhc c cng tu ln mt on nhc cng ta cao nhng ta vn phn bit c ting ca tng nhc c. Nu a cc tn hium ny vo dao ng k in t ta s c trn mn hnh nhng ng cong ccng tn s nhng c dng rt khc nhau (Hnh 2.1). Dng ng cong khc nhau

chng t li ca dao ng m bin i khc nhau. V th, sng m tc dng vomng nh ca tai, lm cho mng nh dao ng theo nhng kiu khc nhau. Do ,ta nghe thy cc m d c sc thi khc nhau. c tnh ca m gi l m sc.

Cng m, mc cng m

Cng m cho ta cm gic nghe thy m to hay nh, mnh hay yu.Cng m c nh ngha l nng lng c sng m truyn qua mt

n v din tch c vung gc vi phng truyn sng trong mt n vj thi gian.

n v cng m l

W

m2 . so snh cng ca mt m vi cng m tiu chun, ngi ta dngi lng mc cng m o bng n v -xi-ben (dB). Mc cng amc nh ngha bng cng thc

L(dB) = 10lgI

I0

Gi m c cng bng cng bng cng m tiu chun l c mc cng

m bng khng -xi-ben II0

= 1 = 100 th m mnh nht II0

= 103 c10


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cng m bng 10 13 = 130dB.Mc cng m ca mt s m thng gp c tr s trong khong t 20 dB

n 100 dB. Chng hn ting ni chuyn bnh thng c mc cng m bng

40 dB.

to ca m

Do c im sinh l ca tai, nn m thanh gy c cm gic m, th cng m phi ln hn mt gi tr cc tiu no gi l ngng nghe. Ngng ngheli thay i theo tn s ca m. V d vi cc m c tn s t 1 000 n 1 500 thngng nghe vo 102 W/m2, cn vi tn s 50 Hz, ngng nghe ln gp 105 ln.

Cm gic nghe m to hay nh khng nhng ph thuc vo cng m mcn ph thuc vo tn s ca m. Vi cng mt cng m, tai nghe c m

c tn s cao to hn m c tn s thp. Do , pht thanh vin n ni nghe rhn pht thanh vin nam.

Khi cng m ln ti 10 W/m2 ng vi mc cng m 130 dB th sngm vi mi tn s gy cho tai ta cm gic nhc nhi, au n. Gi tr cc i cacng m m ti ta c th chu ng c gi l ngng au. Ngng au ngvi mc cng m l 130 dB.

2.2 S ha m thanh

y l qu trnh chuyn i sng m, tc l sng c hc, thnh d liu s clu tr trong my tnh. Qu trnh ny c chia thnh hai giai on: chuyn isng m thnh tn hiu in v chuyn tn hiu in thnh tn hiu s.

Qu trnh chuyn sng m thnh tn hiu in c thu nhn thng qua ccthit b thu nhn m thanh. Dng in c hiu in th dao ng iu ha cngging nh sng m, chnh v vy m ta c th biu din sng m bng tn hiuin.

Tn hiu sng m thanh trong th gii thc c dng tng t (analog). Do , c th lu tr v biu din trn cc thit b my tnh s dng h tn hiu nh

phn, chng ta cn phi chuyn i tn hiu analog sang tn hiu dng s (digital).Tn hiu nh phn khng nhng c biu din v s dng trn my tnh m ncn c ng dng trong rt nhiu cc vt dng khc m chng ta dng hng ngynh: in thoi, my nghe CD, my nghe MP3, ...

Cc bc chuyn sang tn hiu c thc hin nh sauLy mu (sampling)Xt 1 tn hiu m thanh (hnh 2.3) Trong :

Trc X biu din cho min thi gian tnh theo n g giy (s).

Trc Y biu din cho cng tn hiu tnh theo n v Voltage (V).

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Hnh 2.3: Sng m thanh

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Ly mu (sampling)

Chng ta tin hnh ly mu t tn hiu analog theo thi gian.

Mi ln ly mu, gi tr v ln Voltage ca tn hiu s c biu dinbng 1 con s.

S ln ly mu ca chng ta trong 1s c gi l tn s ly mu hay cnc gi l t l ly mu (sampling rate).

Cc loi tn s ly mu ph bin trong my tnh: 8.000Hz, 11.025Hz, 22.050Hz,32000Hz, 44.056Hz, 44.100Hz, 47.250Hz, 48.000Hz, 50.000Hz, 50.400Hz, 88.200Hz,96.000Hz.

Hnh 2.4: Giai on ly mu.

Nhn hnh 2.4, trong th, xt giao im ca th mu vi th mu xanhta c:

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Honh chnh l thi gian t1, t2, . . .

Tung chnh l con s chng ta cn lu tr.

phn gii (resolution)

Nh ni phn trn, mi ln ly mu, chng ta s biu din cng ca tn hiu bng 1 con s.

Nh vy, nu s bit ta dng cho vic ly mu cng cao th thc cng nhkh nng ti to li tn hiu nh ban u cng tt.

Hnh 2.5: phn gii.

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Chng 3

Tng quan v m nhc

m nhc l mt b mn ngh thut dng m thanh (Cht ging) din ttnh cm, xc cm ca con ngi. N c chia ra hai th loi chnh : Thanh nhcv kh nhc. Thanh nhc l m nhc da trn li ht th hin r tng v tnhcm. Cn kh nhc l m nhc da trn m thanh thun tu ca cc nhc c, nntru tng, gy cm gic v s lin tng.

m nhc l mt mn ngh thut phi hp m thanh theo nhng quy lut nhtnh. m nhc bt ngun t nhng m thanh trong cuc sng. Th nhng khngphi m thanh no cng l m nhc. M ch nhng m thanh c tnh nhc. Chngphi c 4 tnh cht c bn sau :

Cao : Mc trm bng ca m thanh

Trng : Mc ngn di ca m thanh

Cng : Mc mnh nh ca m thanh

m sc : Mc d m thanh c ging nhau v cao , v trng , v cng, nhng vn c nhng tnh cht ring bit. Tnh cht ring ca m thanhc gi l m sc .

T nhng m thanh c tnh nhc , lu dn con ngi bit phi hp vic lnxung trm bng to m vc rng v phong ph. V cng t m m nhcc hnh thnh v pht trin.

3.1 Nt nhc c th ha n v cao trong m nhc, ngi ta nh ngha mi nt nhc

l mt gi tr i din cho mt cao nht nh. Nt thp nht tng ng vi tn

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s thp nht khi nghe ting nhc, khong t 20-30Hz. Nt cao nht tng ng vitn s cao nht, khong t 15-20KHz.

Lp nt l tn ca 1 ting nhc. C 12 lp nt c t tn l : C, C , D, D,

E, F, F, G, G, A, A v B. Cc lp nt ny to thnh 1 chu trnh. Mt ng ivng quanh t C-C-D-D-...v tr v C to thnh chu trnh gi l 1 bt /qungtm (Octave), na ng i vng quanh chu trnh t C n F gi l qung nm.

Hnh 3.1: Chu trnh cc lp nt

3.2 Bt Khong cch t nt nhc u tin n nt nhc th 8. Chng hn, ta c khong

cch t nt nhc: -R-Mi-Fa-Sol-La-Si- l 1 bt . Mt khc, n biu dinmi quan h gia 2 nt m trong 1 pitch c tn s gp i tn s nt cn li.Chng hn, khong cch t 100Hz n 200Hz gi l 1 bt .

T hnh Chu trnh cc lp nt, nu nt C4 c tn s l 261,6 Hz th nt C5 ctn s gp i tn s ca nt C4 l 523,2Hz. C C4 v C5 c cng lp nt C.

d hnh dung, ta c th xem cc mc bn m trong 1 bt tng ng vicc v tr trn ng h c biu din trong hnh

Chu trnh cc lp nt: Lp nt

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Hnh 3.2: M hnh biu din vng bt

Hnh 3.3: M hnh biu din cc mc bn m trong 1 bt

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C v tr 12 gi, C v tr 1 gi trn ng h,....chng to thnh 1 chu trnh.Sau y l mt s thng tin v tn cc khong cch gia cc lp nt tng ng vis bn m v t l gia cc tn s :

Tn khong cch T l tn s S bn mng m (Unison) 1/1 0Bn m (Semitone) 16/15 1Qung hai (Second) 9/8 2

Qung ba - nh (Third - minor) 6/5 3Qung ba - ln (Third - major) 5/4 4

Qung bn (Fourth) 4/3 5Qung nm (Fifth) 3/2 7

Qung su - nh (Sixth - minor) 8/5 8Qung su - ln (Sixth - major) 5/3 9Qung by - nh (Seventh minor) 9/5 10Qung by - ln (Seventh major) 15/8 11

Qung tm/ Bt (Octave) 2/1 12

Hnh 3.4: Khong cch gia cc pitch class tng ng vi t l tn s

Khi mt trong s cc ting nhc c chi, chng hn cp C-F, C-G,...ngi

nghe s c cm nhn ting nhc c khuynh hng gim dn. Tuy nhin, khi ccting nhc khc c chi, chng hn F-C, G-C, G-D s nghe ting nhc theohng tng dn.

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Chng 4

Bin i Fourier

4.1 Bin i Fourier ri rci vi mi tn hiu, chng ta c 2 cch biu din di dng min khng

gian hoc min tn s. Vi bin i Fourier, cho ta vic biu din tn hiu trnmin tn s.

4.1.1 nh nghaGi g l hm xc nh trn D = {0, 1,...,M 1}. Xt hm:

G : D Cu G (u) = 1

M

M1x=0

g (x) e2.i.u.x

M

Di quan im ton th php bin i ny l mt cch "biu din li" tn hiutheo mt c s no . Vi php bin i Fourier ri rc, bin mt dy ny thnhmt dy khc c cng kch thc.

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Trn thc t, tn hiu lin tc g(t) thng qua cc b lc ta ly mu g[n] =g(tn), n = 0,..M 1

4.1.2 Bin i Fourier ngcV php bin i ngc

g (x) =1

M

M1u=0

G (u) e2.iu.x

M , x = 0,..,M 1

i vi mt tn hiu, chng ta c th quan st di 2 dng: Min khng gianv min tn s.

Thng qua php bin i Fourier v Fourier ngc, chng ta thy rng mi tnhiu c th biu din c bng c 2 dng trn. Tuy nhin, i vi mt ng dngc th s c nhng im thun li v kh khn ring. Do , s c s chn la tythuc vo vic chng ta s lm nhng g trn d liu y.

V d: Xt tn hiu x(t) = 5cos(.t), 0 t 1, ly mu xn = x(tn), tn = n10

Tn hiu c biu din trn min tn s:

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4.1.3 Cc tnh cht1. Thun nht

Vi R, ta c :F(a.x) = aF(x) (4.1)

Vi a R, ta c :F1(a.z) = aF1(z) (4.2)

2. Tuyn tnh

Vi a, b R, ta c :

F(a.x + b.y) = aF(x) + b.F(y) (4.3)

Vi

a, b

R, ta c :

F1(a.z1 + b.z2) = aF1(z1) + b.F

1(z2) (4.4)

4.1.4 Fast Fourier Transform1. Thut ton Bin i Fourier

Tnh trc tip

Input: M,mng g gm M phn t

Output: Mng h s G;21


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Thut ton :

Khai bo mng G gm M phn tfor m = 0

M

1

G[m]:=0;for n = 0 M 1

G[m] := G[m] +1

M.g[i].e

2i.n.mM

end m;end n;

return G;

phc tp

Gi s mi bc thc hin tn chi ph c nh a th phc tpca tht ton l a.M2

Tip theo, chng ta s tm hiu mt s phng php nhm gim chi ph tnhton h s ca php bin i Fourier.

Ti u gim thi gian thc hin l mt vn m cc lp trnh vin quantm. i vi bi ton ny cng vy, v i vi vic tnh ton cc h s choDFT cho "mu" th chng ta cng khng ti u lm g nhng i vi biton nhn dng chng ta i hi thc hin trn hng ngn mu d liu. Do

, nhu cu trn tr nn cn thit.Trong ng dng m chng ti cn n th dng n M vi c mu kh ln(65536 = 216) v p dng nhiu ln. Do , vic ti u chi ph.

2. Thut ton Fast Fourier Transform

F(f)[m] =1N

Nn=0 f(n)W

mnN , trong :

N = 2n, n N, M := N2

WN := e2.i

N

Ta c :

F(f)[m] =1

2

1

M

M1n=0

f(2n)W2mn2M +1

M

M1n=0

f(2n + 1)W(2n+1)mM

Mt khc :

W2mn2M = W

mnM

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t F(fe)(n) = 1M

M1n=0 f(2n)W

mnM

F(fo)(n) =1

MM1n=0 f(2n + 1)WnmMKhi , ta c :

F(x)[m] =1

2[F(fe)(m) + F(fo)(n)W

m2M] (4.5)

Ta thy F(fe)(m), F(fo)(n)Wm2M l hai php bin i Fourier vi kch thc

mu lN

2. Khi , chng ta thu c thut ton c phc tp O(Mlog2 M)

Thut ton FFT1 (ci tin 1) s dng cng thc (4.5)

function y[k=0...M-1]=splitfftM(xn) :u[k + 2 = 0...M2 -1]=splitfftM2

(x2n2) :

z[k4 = 0...M4 1]=splitfftM4

(x4n4 + 1) :

z

[k4=0...M

4 1]=splitfftM

4

(4xn41) :

for k = 0 toM

4 1 do

y[k] = uk + (WkMzk + WkM

z

k)

y[k + M2 ] = uk (WkNzk + WkM z

k)

y[k + M4 ] = uk+M4

i.(WkMzk

Wk

Mz

k)

y[k + 3M4 ] = uk+M4

+ i.(WkMzk WkM zk)return y;

Ngoi ra, chng ta c th tm thy cc thut ton FFT vi tc c citin ng k khc [4] khi kch thc N l ly tha ca 2.

FFT c xut u tin 1 bi Cooley v Tukey (1965) . Khi kch thc M khng l ly tha ca 2 th ci thin tc , chng

ta s thc thi trn tp nhng im tng ng l c nguyn t ca M.Vi tng ny cng em n hiu qu trong vic ci tin tc chothut ton, theo thut ton Winograd c cp trong [5] . Tuy nhin,chng ta phi phn tch N thnh tha s nguyn t, y l mt bi tonn gin v hnh thc nhng li c phc tp cao (Thut ton phntch c tc nhanh nht hin nay c phc tp O(e

n log2 log2 log2 n)).

loi b chi ph tnh ton, do kch thc M ta hon ton c th qunl, v vy ta hon ton c th ly mu theo kiu chia i nh phn c kch thc mu lun m bo l ly tha ca 2.

1Trc ,nm 1805, Gauss tng m t tng ny

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Mt s nh gi v DFT

Thun li DFT s em n thun li khi ta mong mun kho st tn hiu v mt

tn s.Kh khn Khi nhn tn hiu trong lnh vc tn s th "mt" i thng tin cc b

v mt thi gian.

Vic nm bt thng tin cc b v mt thi gian cng em n nhng iu c chcho qu trnh phn loi nhc.

Chnh iu , t ra mt nhu cu l khc phc nhc im trn c haicch gii quyt vn ny: dng STFT(Short Time Fourier Transform) thaycho DFT v bin i Wavelet.

4.2 Bin i STFTNi dung ca phng php ny c th qua tn gi STFT, c th tm dch

l bin i Fourier trong khong thi gian ngn. tng: i vi tnh hiu thi gian ban u x(t), t [a, b], ta tin hnh chia

khong thi gian chia nh on [a, b] thnh cc on nh. Ta tm gi tn hiu chn ch trn mi on l mt ca s. Tip theo ta thc hin bin i Fourier, tuynhin vi mong mun tng cng tc tnh ton nn ta s dng FFT, c ngha

l vic chn s im mu phi tng thch vi FFT.Chnh hng tip cn trn mang n thng tin cc b trn lnh vc thigian m chng ta mong mun.

Tuy nhin, chng ta cng i mt vi nhng thch thc do STFT mang li

Phn tch cc tn s vi cc ca s c rng nh nhau.

Kh khn trong vic xc nh rng ca ca s sao cho ph hp. V nuca s hp, hiu qu trong vic phn tch thi gian nhng km hiu qu trongvic phn tch tn s. Ngc li, nu ca s rng, km hiu qu trong vic

phn tch thi gian (vi phm iu kin tn hiu phi dng) nhng hiu qutrong vic phn tch tn s.

iu ny c th hin thng qua nguyn l bt nh.

Cho x(t) trit tiu nhanh hn1

tth t

2, trong :t, ln lt

l rng thi gian, tn s ca tn hiu x(t)

Nguyn l ny c ngha quan trng trong vic a ra nt ti a cho c

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4.3 Nhng hn ch ca FT v STFT

4.3.1 Hn ch ca FT FT ch cha cc thng tin v tn s, khng cha cc thng tin v thi gian.

p dng ph hp i vi cc tn hiu dng (stationary signals) tc l tnhiu khng ph thuc vo thi gian, v d nh tn hiu mng tnh tun hon.

Khng ph hp vi tn hiu khng dng (nonstationary signals) tc l tnhiu ph thuc vo thi gian, thng xuyn thay i. FT biu din cc tns xy ra mi thi im thay v cc thi im xc nh.

4.3.2 Hn ch ca STFTHn ch i vi phng php STFT l:

Phn tch cc tn s vi cc ca s c rng nh sau.

Kh khn trong vic xc nh rng ca ca s sao cho ph hp . V nuca s hp, hiu qu trong vic phn tch thi gian nhng km hiu qu trongvic phn tch thi gian (vi phm iu kin tn hiu phi dng) nhng hiuqu trong vic phn tch tn s.

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Chng 5

Phn lp K - NearestNeighbor

5.1 Khai khong d liuNgy nay, vi s pht trin ca x hi, chng ta phi i din vi mt tp d

liu rt ln vi hng trm ngn mu tin, thm ch hng triu mu tin nh b sutp nhc, b su tp cc trang web, virus my tnh. . . Vi tp d liu ln nh vy,ngi ta mong mun trch chn cc thng tin hu ch, cc quy lut tim n trongtp d liu nhm a ra nhng quyt nh ti u p ng mt s kin xy ra

trong thc t hoc d bo tnh hung tng lai. chnh l nhim v ca khaikhong d liu (Data mining).

Data mining, ni chung, l mt bi ton c phc tp ln bi v ta phi lmvic vi mt khi tp d liu rt ln. Chng ta c th hnh dung vic khm phtri thc ging nh vic khai thc mt m khong sn, trong m c nhiu kim loitrn ln nh vng, ng, ch, ...Nhim v ca khai thc mt m khong sn lphi loi b nhng tp cht tch ring cc kim loi trong m, c bit l cckim loi qu. Khm ph tri thc trong c s d liu cng ging nh tch bit cvng trong mt m khong sn.

5.2 Phn lp l g?Trc ht, chng ta nh ngha th no l phn lp. Gi s chng ta c hai

loi khng gian: khng gian u vo X v khng gian u ra (khng gian nhn)Y. V d, ta phn loi cc loi i tng bit cho trc, hu hn bao gm xehi, gh, b, X l khng gian bao gm cc i tng , Y l khng gian ccloi xe hi, gh, b. Trong qu trnh hc, thut ton hc s cho tp hunluyn mu (X1, Y1), . . . (Xn, YN), v gn nhn cho tng i tng vi cc nhn l

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xe hi, gh, b. Nh vy, nu ni theo ngha ton hc l ta i tm mt nh xf : X Y v lm cho li t nht c th c, c ngha l vi khng gian X, tamong mun cho s cc i tng c gn nhn sai l thp nht c th. nh xf : X Y c gi l hm phn loi.

By gi, chng ta s phn bit hai loi vn hc: hc gim st v hc khnggim st. Phn lp l v d v hc c gim st, mu hun luyn bao gm c Xic gn nhn l Yi. Mc ch ca phn lp l tm hm quan h gia khng gianu vo X v khng gian nhn Y. y c gi l hc c gim st v trong muhun luyn, ngi hc c th nh gi p n ng hay khng, v ngi hc cgim st. Tri li vi hc c gim st, hc khng gim st c khng gian u voch bao gm Xi, trong khi thng tin v cc nhn khng c bit trc. Lcny, qu trnh hc l khm ph ra cu trc n di d liu u vo. Mt v d

ca hc c gim st l phn cm. Cho trc mu d liu u vo X1, . . . , X n, ngihc cn phi thit lp cc nhm gia cc mu. V d, mt ngi bn hng Onlinemun phn cm khch hng ca anh ta da trn lch s mua hng. Anh ra chntt c khch hng c tim nng v sau khm ph nhm khch hng ny v stng ng v s thch. Tri ngc vi phn lp, phn cm khng h bit trc,n s a khch hng thuc v nhm no - l nhim v ca thut ton phn cm.

5.3 Phn lp k - Nearest Neighbor

5.3.1 Phn lp 1 - Nearest NeighborGi s ta c Dn = {x1, x2, . . . , xn} l mt tp n mu u tin (d liu hun

luyn) c gn nhn. Cho mt im x cha c phn loi, nhim v y lxc nh xem x thuc lp no, tc l ta xc nh nhn ca x. Khi , nguyn tc 1- Nearest Neighbor i vi vic phn loi l gn cho n nhn th loi ca mu gnvi n nht trong tp Dn, ngha l ta xc nh mu x Dn, vi x l mu hunluyn gn vi x nht, ta s gn nhn x l nhn ca x (xem hnh 5.3.1).

Ta gi f l nh x ca mu x vo khng gian nhn. Lc ny, ta s vit cng

thc xc nh nhn ca mt mu x mi nh sau.d(x, x) = min d(xi, x) xi Dn

f(x) = f(x)

5.3.2 Phn lp k - Nearest NeighborPhn lp k - Nearest Neighbor l kiu m rng ca phn lp 1 - Nearest

Neighbor da trn khong cch. N lu tr tt c cc mu hun luyn trc.

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Hnh 5.1: Phng php phn loi 1 - Nearest Neighbor

Sau , n xc nh khong cch gia mu cn kim tra vi tt c cc mu c hun luyn v chn ra k mu hun luyn gn vi mu kim tra nht, gi lphn lp k - Nearest Neighbor. Kt qu ca vic phn loi l nhn ca mu huncn xc nh nhn s l nhn ca loi no xut hin nhiu nht trong k mu gn

mu cn xc nh nhn(xem hnh 5.3.2).Thut ton phn lp nh sau:

Input: mu x cn xc nh nhn.

Output: Nhn ca x.

1. Cho mu x cn phn lp.

2. Gi x1, x2, . . . , xk l k mu trong kho mu hun luyn gn x nht.

3. Xc nh nhn f(x) ca mu x t nhn f(x1), f(x2), . . . , f (xk).Vic hc trong thut ton phn lp k-NN ch n gin l lu tr d liu hunluyn. Khi cn phn loi i tng mi, mt tp cc i tng gn ging hay

tng t s c chn ra t kho d liu c sn v c s dng phn loi itng mi.

s dng thut ton KNN cho vic phn loi i tng mi, ta cn xc nhcc yu t sau:

Cn phi xc nh tham s k. Vi gi tr k no th vic phn loi s t chiu qu cao nht.

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Hnh 5.2: Phng php phn loi k - Nearest Neighbor

Dng loi khong cch no? Dng thuc tnh no c c kt qu ttnht, ta s dng ht tt c cc thuc tnh hay ch nhng thuc tnh chnh.

5.3.3 u im, khuyt im

u im D phn tch.

Thc hin n gin.

D thc hin vic so snh

Hiu qu khi tp hun luyn ln

Khuyt im Ta cn tnh ton khong cch gia tt c cc im vi im truy vn, do vic tnh ton nhiu. Chnh v vy, thut ton phn lp KNN c phc tpcn cao O (kN).

Chi ph cho vic phn loi i tng mi c th tn km do gn nh ton bchi ph tnh ton din ra lc phn loi i tng mi ch khng din ra lchun luyn d liu.

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Nu c trng phn loi i tng ch ph thuc vo mt s t trong snhiu thuc tnh sn c ca i tng th nhng i tng tht s tngt c th cch nhau rt xa.

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Phn IIBi ton phn loi nhc theo

th loi

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Chng 6

Gii thiu bi ton

6.1 Nhu cu thc tTh loi nhc c s dng phn bit cc loi nhc khc nhau. Vic gia

tng s lng cc file nhc, c bit l World Wide Web, v nhu cu l cn mth thng phn loi nhc t ng. Loi ng dng ny c nh km vo cc phnmm qun l nhc. Mt cu hi t ra, chng ta phn loi nhc da vo tp ccc trng v m nhc v a ra thut ton rt trch c trng t tn hiu audiophc v cho vic phn loi nhc. Mt trong nhng cong c chnh phn tch tnhiu audio l php bin i Fourier. Tuy nhin, php bin i Fourier gp phi

mt s hn ch trong vic phn tch tn hiu audio. V vy, ngi ta s dng mtcng c khc da trn php bin i Fourier x l tn hiu audio hiu qu hn php bin i Wavelet. Php bin i Wavelet ph hp trong vic x l tn hiuc bit l cc tn hiu khng dng (thng xuyn thay i).

6.2 Gii thiu bi ton phn loi nhc theo thloi

Bi ton phn loi xut hin rt lu i, v d vic sn ct xy nh, sn go nucm...cng l vic phn loi. Nhu cu ngy cng cao, m nhc tr thnh phngtin nng cao gi tr tinh thn cho i sng. Song song, l vic mong munqun l cc bi ht vi d liu ngy cng nhiu, do , chng ta cn xy dng mtc s d liu. C nhiu cch phn loi nhc, v d nh phn loi nhc theo tcgi sng tc, theo ca s, v theo th loi . . . Trong khun kh bi bo co ca nhmchng ti, chng ti xin trnh by hng phn loi nhc theo th loi.

T ngy xa, mun bit mt bi nhc thuc th loi no, chng ta thng davo kinh nghim ngi nghe. Tuy nhin, bit mt bi nhc thuc th loi no,

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chng ta thng tm tn bi ht, tc gi, ca s ht bi xc nh xem bi ht thuc th loi no. V d nh khi ta nghe mt bi ht ca mt tc gi chuynsng tc nhc pop, th l ta s quy bi ht thuc th loi nhc pop. Hoc l,

khi ta nghe mt bi ht do mt ca s chuyn ht nhc rock, th l ta quy bi htl nhc rock. Ngoi ra, vic phn loi nhc ca con ngi c th da vo cc loinhc c c s dng trong bi nhc. Tuy nhin, vi s pht trin ca cng ngh,s lng bi ht cng nhiu, chng ta khng th no ngi nghe tng bi ri kt lun bi nhc thuc th loi no. Chnh v vy, nhm chng ti xy dng mtchng trnh phn loi nhc p ng nhu cu .

Cc h thng phn loi nhc theo th loi thng m phng nhng k nngca con ngi chng ta c th nhn bit c th loi ca bn nhc. Tuy nhin,chng khng th phn loi nhc ch yu da vo kinh nghim ngi nghe nhc mcn thit phi xc nh mt s c trng chung, phc v cho vic nhn dng theoth loi.

Mt th loi nhc l mt tp cc c trng chung m ngi nghe c th phnbit n vi nhng loi nhc khc t nhng bn nhc khc nhau. Nhng c trngc th c k nh l: cao thp nt nhc (pitch), m sc (timbre), nhp (rhythm)ca bn nhc hoc nhng c trng lin quan n b cc nhc (music texture).Mt trong nhng thch thc trong phn loi th loi nhc t ng l tm ra ccyu t .

Trong bi bo co ca nhm chng ti, chng ti ch s dng b cc v m sc phn loi th loi nhc. Cc tn hiu audio c phn loi mt cch t ng

thuc mt trong cc th loi sau: Classical, Rock, Jazz, Pop, blues, country, disco,hiphop, metal, reggae. Nhm chng ti th nghim vi 10 th loi nhc ny, v 4th loi Classical, Rock, Jazz, Pop.

Hnh 6.1: S xc nh th loi nhc t tn hiu audio.

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6.3 M hnh tng qut h thng phn nhc theoth loi

Hnh 6.2: M hnh phn loi nhc tng qut.

M t h thng:

u vo l mt tn hiu nhc c s ha. Rt trch c trng l qu trnh biu din tn hiu nhc di dng vector

c trng c s chiu nh hn so vi thng tin gc, rt trch cc c imring cn thit phn bit cc th loi nhc khc nhau. Trong bi bo coca nhm chng ti, chng ti s dng c trng v b cc v m sc chovic phn loi th loi nhc. Cng c rt trch c trng b cc v msc da trn php bin i Fourier v Short time Fourier. Chi tit vic xcnh c trng b cc v m sc c trnh by mc 7.2

Phn lp l t cc c trng c rt trch, tin hnh phn loi nhcbng cc phng php nhn dng: K-nearest neighbor, SVM, Neuron Net-work...Vic phn loi thng gi l hc c gim st (supervised learning).Hc gim st bao gm vic s dng cc vector c trng c gn nhn hun luyn cho cc b phn loi. T , b phn loi s gn nhn loicho cc cc vector c trng mi mt cch t ng. Trong bi bo co canhm chng ti, chng ti s dng phng php phn loi K lng ging gnnht (KNN, K Nearest Neighbour) v phng php ny c mt s u imsau:

D phn tch. Thc hin n gin. D thc hin vic so snh Hiu qu khi tp hun luyn ln B sung mu hun luyn vo b hun luyn mt cch d dng.

u ra l nhng thng tin v tn hiu u vo v cho bit tn hiu u vothuc v th loi nhc no.

Chi tit phng php phn loi KNN c trnh by chng 5

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Chng 7

Thut gii

7.1 Rt trch c trng xc nh th loi ca mt bi nhc, chng ta cn xc nh c trng ca

chng sao cho my tnh c th phn bit s khc nhau gia cc loi nhc. Chngny s gii thiu mt s phng php chnh trong vic rt trch c trng cc tptin nhc v cp c trng thng s dng trong phn tch nhc.

Rt trch c trng l qu trnh x l tnh ton a ra cc c trng cnthit cho vic phn loi nhc. Ngoi ra, vic chn lc c trng c dng tora mt tp con c trng t d liu u vo s lm gim s chiu v do s lm

tng hiu qu v mt thi gian nhn dng.Trong bi bo Musical Genre Classification of Audio Signals ca George

Hnh 7.1: S mt vector c trng t mt tn hiu nhc.

Tzanetakis v Pery Cook, nhm tc gi s dng ba tp c trng sau:

Cc c trng lin quan n b cc m sc (Timbral Texture Features). Cc c trng lin quan n nhp nhc (Rhythmic Content Features). Cc c trng lin quan n cao thp nt nhc (Pitch Content Features).

Tuy nhin, do hn ch v trnh v thi gian, trong bi bo co ca nhm chngti ch s dng cc c trng v b cc m sc cho vic phn loi nhc.

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7.2 Cc c trng lin quan n b cc m sc(Timbral Texture Features)

Qu trnh xc nh cc c trng v b cc m sc c m t bi s sau:Cc c trng lin quan n b cc m sc c xc nh da trn STFT v

Hnh 7.2: S xc nh cc c trng lin quan b cc m sc.

c tnh trn mi ca s. Sau y l cc c trng c dng biu din bcc m sc.

Spectral CentroidSpectral Centroid c nh ngha l o lng phn b nng lng ca phbin khi thc hin STFT tn hiu.

Ct =

Nn=1 Mt[n] nNn=1 Mt[n]

(7.1)

trong Mt[n] l bin ca bin i Fourier ca s t ng vi tn s n. Centroidl mt o v trng thi ca ph. Cc gi tr Centroid cao hn tng ng vi

ph c sng chi hn v cha nhiu tn s cao.

Spectral RolloffSpectral Rolloff c nh ngha nh mt tn s Rt sao cho c khong 85%

phn b nng lng c tp trung

Rt

n=1

Mt[n] = 0.85 N

n=1

Mt[n]. (7.2)

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Rolloff cng l mt o v trng thi ca ph. N cho bit nng lng ca tnhiu tp trung cc tn s thp.

Spectral FluxSpectral Flux c nh ngha l bnh phng hiu gia cc bin chun

ca s phn b ph

Ft =Nn=1

(Nt[n] Nt1[n])2 (7.3)

trong Nt[n] v Nt1[n] bin chun khi thc hin bin i Fourier ca s tv t 1 trc .

Nt[n] =

Mt[n]Ni=1 (Mt[i]

2) (7.4)

Spectral Rolloff l o v s thay i ph bin cc b.

Time Domain Zero CrossingsTime Domain Zero Crossings l o n ca tn hiu. N xut hin khi

cc mu k nhau trong tn hiu s khc du.

Zt = 12

Nn=1

sign (x[n]) sign (x[n 1]) (7.5)Trong :

sign (x[n]) =

1 x[n] 00 x[n] < 0

x[n] l tn hiu trong ton min thi gian ca s t.

c trng Low EnergyLow Energy l o t l phn trm ca s phn tch nng lng RMS thp

hn nng lng RMS trung bnh ca cc ca s phn tch. Root-Mean-Square(RMS) c xc nh bi cng thc:

RMSt =

Ni=1

Mt[i]2

N

(7.6)

RMS l o to ca m thanh trong mt ca s.

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Mel-Frequency Cepstral Coefficients (MFCC)Cc h s MFC (Mel-Frequency Cepstral Coefficients) c xc nh da trn

STFT. u tin, tn hiu nhc c thc hin bi FFT sau qua cc b lc bngtn (Mel-Scale Filters), kt qu c chuyn qua log c s 10, v cui cng l quaphp bin i cosin ri rc a ra cc c trng v m nhc (tng t nh cquan thnh gic ca con ngi).

Tn hiu u tin c chia nh thnh cc ca s tn hiu thnh phn, sau p dng cc bc sau tnh cc h s MFC.

Bc 1: Thc hin FFT trn mi tn hiu thnh phn.

Bc 2: Kt qu c xc nh bi bc 1 s c a qua mt lot bngtn, cc b lc ny c xy dng bng cch dng 13 b lc tuyn tnh(khong cch gia cc tn s trung tm l 133.33 KHz) v theo sau bi 27b lc phi tuyn (mi tn s trung tm cch nhau bi mt h s nhn ca1.0711703).

Bc 3: Kt qu bc 2 c bin i sang log c s 10.

Bc 4: Thc hin bin i cosin ri rc kt qu bc 3. Kt qu ta c1 vector c trng gm 13 h s.

13 h s ny c dng nhn dng ging ni. Tuy nhin, ta ch chn 5 h s MFC

u tin cng tt cho vic phn loi nhc.

Vector c trng b cc m scVector c trng b cc m sc bao gm cc c trng: (Trung bnh v phng

sai ca Spectral Centroid, Spectral Rolloff, Spectral Flux, ZeroCrossing(8), LowEnergy(1), v trung bnh v phng sai ca 5 MFCC u tin (10)).Ta c kt qu trong 1 vector c trng 19 chiu.

7.3 Ci tinVic rt trch c trng c trnh by phn trn s a ra cc h s th

hin c trng v b cc m sc. Tuy nhin, chng ta gp phi mt vn nh thny. l cc h s trn cha a v mt kch thc chun. Chnh v vy, chngti xut mt cch a cc h s v mt kch thc chun.

Chng ti chun ha cc h s bng phng php nh sau. Chng ti ch xtn mt h s trong 19 c trng, cc h s cn li lm tng t. Chng ti cgng min gi gi tr ca c trng v dng tng ng ( y c th l t [0, 1000].

Gi s ta c mt dy h s u tin trong 19 c trng, l mt chui x1

, x2

, . . . , xn,

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vic chun ha s c tnh theo nh sau :Gi l h s chun ha cho c trng vi tp mu hun luyn tng ng

=

1000

maxk=1,...,n xk

xi xivi i = 1, . . . , n, n l s vector c trng ca mu hun luyn.

Vi hi vng l a dng ca tp dng hc l cha gi tr ln nht cth ca mt c trng hoc nu c ln hn th cng khng qu ln. V vy chngta c th p dng cng thc trn cho cc c trng a vo phn loi sau ny.Vi mi ln thm c s d liu c, th chng ta tin hnh thc hin li hmtm .

Vector c trng ca mt tp tin nhc cn phn loi, chng ta s nhn gi trca tng c trng vi h s chun ha () tng ng.

7.4 Khong cch gia hai muTt c cc mu c xem nh l cc im biu din trong khng gian Rn.

Khong cch mu lng ging so vi mu cn kim tra l d(k, x) c xc nh datrn khong cch -clit (k l mu lng ging, x l mu cn kim tra. Xc sut camt mu kim tra x thuc th loi ci c xc nh nh sau:

p(ci|x) =

kU,kc=cj wkkU

wk

Trong :

U l mt tp hp gm k mu lng ging gn x nht, k l mu lng ging gnx nht (k U).

kc l th loi ca k v d(k, x) l khong cch -lit t k n x.

ci l th loi th i, i = 1, n (h thng c th c n = 4 th loi hoc n = 10

th loi).Mu cn kim tra x c gn nhn th loi ci khi p(ci|x) l ln nht.Xc nh khong cch -clit

C nhiu cch xc nh tnh ng dng ca cc vector c trng. Thu tonKNN thng da trn vic xc nh khong cch gia cc vector c trng trongkhng gian Rn. Khong cch s dng l khong cch Minkowski:

dp(xi, xj) =p

d

m=1

(|xi,m xj,m|)p = xi xjp

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Thng thng ngi ta dng khong cch -clit xc nh khong cch giacc i tng trong khng gian trong khng gian Rn. Khong cch -clit l mttrng hp c bit ca khong cch Minkowski vi p = 2.

d2(xi, xj) =p

dm=1

(|xi,m xj,m|)2 = xi xj2

Trong , xi v xj l cc mu ang xt (i = j), d l s chiu ca vector c trng.i vi h thng phn loi nhc theo th loi, chng ta s s dng vector c trng19 chiu, nh vy cng thc trn d = 30.

7.5 Hun luyn v nhn dngTrong giai on hun luyn v nhn dng, chng ta s rt trch c trng tng

tp tin nhc v lu tr li cc c trng . Vic lu tr ny rt c ch. V trongqu trnh nhn dng, nu nh ta khng thc hin bc trn, ta s phi tn mtchi ph tnh ton cho vic phi rt trch c trng cc tp tin nhc mu. Nu nhta rt trch c trng v lu xung a th trong giai on nhn dng, ta s gimc mt lng chi ph tnh ton ln.

Trong giai on nhn dng, chng ti s dng K-nearest neighbor nhn dngxem mt tp tin nhc u vo thuc th loi nhc no. Phng php K-nearest

neighbor chng ti trnh by chng 5. Chng ti s dng k = 1, . . . , , 10 chovic phn loi tp tin nhc v khong cch -clit xc nh khong cch giahai mu.

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Chng 8

Thc nghim, kt qu vnhn xt

Trong thc nghim khai trin, nhm chng ti pht trin trn ngn ngC++, do thi gian hn hp v kin thc c hn nn d c nhiu c gng nhngchng ti ch hon thnh 19/30 c trng so vi lun vn ban u.

8.1 Kho mu thc nghimTn kho mu : GTZAN Genre CollectionS th loi nhc : 10

Blues

Classical

Country

Disco

Hiphop

Jazz

Metal

Pop

Regguae

Rock

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S mu dng hc : 900S mu dng phn loi : 100

8.2 prjMusicalClassificationNgn ng thc hin : C++S c trng c s dng : 19

Tn c trng S c trngSpectral Centroid 2

Rolloff 2Flux 2

ZeroCrossing 2LowEnergy 2MFCC 10

8.2.1 Th nghim vi 10 th loiKt qu 1 : T l chnh xc khng dng chun ha o (Tnh theo %).Kt qu 2 : T l chnh xc khi dng chun ha o (Tnh theo %).

k Kt qu 1 Kt qu 21 22 462 22 463 26 494 24 515 24 506 25 517 22 498 23 509 25 48

10 25 47

8.2.2 Th nghim vi 4 th loi nh trong lun vn banu

y l 4 th loi trong lun vn m nhm da vo tin hnh nghin cu.Cc th loi nhc :

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Hnh 8.1: Biu tng quan chnh xc phn loi 10 th loi

Classical Jazz

Pop Rock

k Kt qu 1 Kt qu 21 32.5 752 32.5 753 37.5 77.54 40 77.55 37.5 77.56 37.5 77.57 35 758 35 72.59 35 77.5

10 35 72.5

8.2.3 Th nghim vi 4 th loi tt nhty l 4 th loi c kt qu tt nht trong qu trnh thc nghim.

Cc th loi nhc:

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Classical

Country

Pop Rock

k Kt qu 1 Kt qu 21 45 852 45 853 50 904 50 905 60 90

6 57.5 907 55 87.58 52.5 87.59 52.5 87.5

10 55 90

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8.3 Hnh nh chng trnh thc nghim

Hnh 8.4: Trch xut gi tr cc c trng

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Hnh 8.5: Phn loi vi 4 th loi

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Hnh 8.6: Phn loi vi 10 th loi (1)

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Hnh 8.7: Phn loi vi 10 th loi (2)

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8.4 Kt lunVic phn loi nhc theo th loi chng ti da vo bi bo Music Genre

Classification of Audio Signal ca George Tzanetakis v Perry Cook, chng tich s dng c trng b cc v m sc (19 c trng) cho vic phn loi nhc.Tuy nhin, chng ti c ci tin v 19 c trng u, l a mi h s v kchthc chun, chng ti gi l bc cn bng h s. Chng ti t c mtkt qu rt kh quan. Sau khi thc hin bc cn bng h s, chng ti t cmt kt qu vic kt qu phn loi ng cao hn so vi cha cn bng h s.

Vic phn loi t kt qu chp nhn c.

8.5 Hn chH thng ch h tr nh dng WAV, AU.H thng ch h tr trch xut 30 giy nhc.Hin nay s lng bi nhc tin hnh hun luyn v th nghim u code tnh

trong source.

8.6 Hng pht trin

Tng cng mu hun luyn nng cao chnh xc.. . .Xy dng giao din nhm d s dng....H thng s h tr nhiu tp tin nhc dng khc nh: MP3, WMA, OGG,

FLAC...H thng s h tr y cc tp tin nhc c nhng di thi gian khc

nhau.Thit k vi h thng phn loi khc nh: Support Vector Machine, mng Neu-

ron, Bayes, . . .Nghin cu thm c th s dng Wavelet rt trch c trng v nhp

nhc, cao ca nhc tng cng chnh xc.

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Ti liu tham kho

[1] Phan Anh Cang. Phn loi nhc theo th loi dng php bin i wavelet rirc. Lun vn thc s. i hc Khoa Hc T Nhin TP. H Ch Minh, 2004.

[2] Perry Cook George Tzantakis. Music genre classification of audio signals. IEEETrans, 10:293302, 2002. 5.

[3] Trnh Tn t, ng Nguyn ng Nguyn, Phm Ngc Tun, NguynHng Khoa. Truy vn nhc bng hm. In Tr tu nhn to. 2010.

[4] Xuancheng Shao and Steven G. Johnson. Type-ii/iii dct/dst algorithms withreduced number of arithmetic. Department of Mathematics, Massachusetts In-stitute of Technology, Cambridge, 2007.

[5] S. Zohar. Winograds discrete fourier transform algorithm.

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