Multimedia Technology - PowerPoint PPT Presentation

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Multimedia Technology

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Title: Multimedia Technology Author: Billgates Last modified by: djhuang Created Date: 2/10/2004 7:34:51 AM Document presentation format: – PowerPoint PPT presentation

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Title: 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
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