Multimedia Technology

1
?????

• ????????????? ???

2
??? ??????

• 2.1 ???????????
• ?? ????????????????

????
??
t
??
3
??? ??????

• 2.1 ???????????
• ?? ????????????

20 Hz
0 Hz
20 kHz
Human hearing frequency range ????(audio)
??? Subsonic
??? ultrasonic
4
??? ??????

• 2.1 ???????????
• ??????
• ????????(?????)????????
• ??????
• ????????????????????

5
??? ??????

• 2.2 ????????
• ?? ???????????????,????????????????

????
t
T
????(??f1/T)
6
??? ??????

• 2.2 ????????
• ???? ????????????
• e.g. CD-Audio 44.1 kHz
• ???????? 11.025 ? 22.05 ?8 kHz
• ???????
• ????????????????????????????????
• e.g. 8-bit ???????? 256 ????
• 16-bit ?CD-DA??????

7
??? ??????

• ????????????

0.75
???
0.5
0.25
t
0
- 0.25
- 0.5
- 0.75
8
??? ??????

• ????????????

9
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• ???MIDI? MIDI?????????????????????/??????(??)?
• MIDI ???????
• ?? MIDI ??, MIDI ??,
• ???? MIDI ??

10
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• MIDI ?? ??MIDI????????????
• ???(Sequencer)??????????MIDI?????????

11
??? ??????

• ????????????

12
??? ??????

• ??? ??MIDI????????????????
• ??????
• ????? ???? ????
• ???? ????/??MIDI??
• ?? ???
• ???

13
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• MIDI ?? MIDI???????????MIDI??????????MIDI??????
  ?C,??????MIDI???

14
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• MIDI ?? MIDI???MIDI??????????
• Format of a MIDI message

channel bits
Message type
Data bytes
1
4 bits
3 bits

Status byte
15
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• MIDI ?????
• ? ????(Channel Message )
• - ??????
• ??(pitch )
• ??(amplitude )
• ????(duration)
• ??????

16
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• - ??????
• ????MIDI????MODI?????????Local Control,
  All Notes Off, Omni mode off, ?.

17
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• ? ????
• - System real-time messages e.g.System Reset
• - System common messages e.g.Song Select
• - System exclusive messages

18
??? ??????

• 2.3 MIDI Musical Instrument Digital Interface
• MIDI ??

MIDI Keyboard
MIDI Card
PC
Sound sources such as drum editors