- ??????? (2) ??

1
?????? (5)
- ??????? (2) ?????????
2001.05.15
???????? ???? E-Mail katto_at_katto.comm.waseda.ac.
jp
2
?????????? ??
3
??????????

• ???????

?????????????
???
?????????
?? 8 kHz ?8 ???
????? 22.5, 44.1, 48 kHz?16 ???
4
??????
5?????
???
0.1 ?????
??? (218ms) ??????7ms
5
?????????
8?????
0.1 ?????
???
6
?????????????
kbit/s
512
PCM
?????
CD/DAT
????? (???????)
256
MPEG1
128
MPEG4
64
G.726 (ADPCM)
G.711 (PCM)
32
??
G.728 (CELP)
16
G.723.1 (CELP) G.729 (CELP)
GSM (CELP)
8
???? (?????)
VSELP
AMR (CELP)
4
PSI-CELP
??
CELP (?????)
2
40
80
90
00
?? ?????
7
????? (1)

• ???????

??????????? (??) ??????

• ???? (????)
• ?????
• ???
• LPC?????

?????
???
?????
?? (????)
?????
?? (????)
x
???
??????
G (???)
LPC????
L.Rabiner et al Fundamentals of Speech
Recognition
8
????? (2)
CELP Code Excitation Linear Prediction

• CELP (LD-CELP ??)

CELP ??????????????????? ?????????????????????
???
?????
????
???? ???
-
????
?????? (????) ???
??
??????
??
?????
LPC??
??????
LPC?????????????????????? (?????CELP????????)
???
??????
?????
LPC??
????
??????
?? ?????
9
????? (3)

• LPC ?? (??????) ?????

LPC Linear Prediction Coding
s(n) ?????? ak LPC?? p LPC???? G
????? u(n) ??????
??? k ?????????????
(?) ????????????????
????????????
????? (Durbin???????)
10
????? (4)

• ??????? ??????

?????????????
d ??? x ?????? (????) A LPC???? g ??? c
?????? (????)
????????????????
????????? ...
??? ???
???? ???
??
??
?????
?????? ? ???????
??
??? ? ???????
??? ???
????
(??????? ? ???????)
11
????? (5)

• ??????? ????????? (1)

K-???????? (??? Lloyd ??????)
???? (??????) ???
(M ???????)
??? ?????????
(L ???????)
??? (NN) ??
(???????????)
????????
?? ??????????????
12
????? (6)

• ??????? ????????? (2)

???????? ???? (???)
LBG ??????
??????
??? ?????????
??? (NN) ??
????????
k-????????
13
???????? (1)

• ???????????

• ??????????? FFT???????? (QMF)?MDCT
• ?????? ??????????
• ????????????? ??????????????

14
???????? (2)

• ??????

???? ????????????????????????
??
????
???
?????
????? (????) ???????????????????????????
??
????
?????
???
15
???????? (3)

• MP3 (MPEG-1 Layer III)

????????
QMF
??????? MDCT
??????
???????
FFT
??????
?????
cf. Layer I, II
16
???????? (4)

• MPEG-2 AAC

??????? MDCT
??? ???
???? ???
???? ?????
??
??????
?????

• ????????? (for transient signals)
  ???MDCT???????????
• ???? (LPC) ?????????????????????? (?????)?
• ?? (for stationary signals) MDCT???????2?????MDC
  T???????
• ?????????????

17
???????? (5)

• Twin VQ

??????? MDCT
??? ??????? ????
?????
??????
???? ???
LPC??
???? ???

• LPC????????????????? MDCT??????????????
• ??????????
• ?????????????? ??????????????????????
• ??????????????

18
???????????????

• ?????

PCM ? ????? ? ??????? (???????)

• ???????????????

PCM ? ????? ...
?????????? ?? ( ????) ???????? ??????????????
????????? (???????????????)
???????? ???? ?????? ????? (??????????)