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Related Technology
Video/Audio
Capture & Display
Convert Analog Video/Audio into
digital
Transmission and display
in main memory of PC
Video/Audio Compression Technology
Video : H.263 compression, MJPEG
- Audio : ADPCM,
CELP,,,
Streaming Technology
Image transmission via PSTN, ISDN and exclusive line
Video tracking, transmitting and controlling
Video Compression
1) Compression Method
Compression by using space
correlation within screen
Compression
via time correlation between screens
Compression
by using bias of code occurrence probability
2)International Standard
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Name of International Standard
|
Quality
|
Speed
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Mode
|
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H.261
|
Narrow-band, Video telephone, Conference |
64~1920kbps |
Mode DCT, MC, estimation between
frames |
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H.263 MPEG-
|
Video telephone, Conference |
61kbps |
DCT, MC, estimation between framesImprovement
of H.26 mode |
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1 MPEG-1
|
VTR, Video CD |
1~1.5Mbps |
DCT, MC, two-way estimation between
frames |
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1 MPEG-2
|
TV quality or more, HDTV quality |
4Mbps or more |
DCT, MC, two-way estimation between
frames/fields |
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MPEG-4
|
For multimedia communication, object
oriented communication, Compression of high efficiency |
10kbps ~ 1Mbps |
Apply various compressing algorithm.
Menu selection |
Audio Compression
1) Compression Method
Modeling via the theory
of voice occurrence
Compression via human voice
feature
Compression via vector quantization
2) Comparison of Voice Compressing Methods
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Mode
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Algorithm
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Speed
|
Quality
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Complication
|
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Waveform Coding
|
PCM
|
64kbps
|
Very
good
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Low
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ADPCM
|
16,
32kbps
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Good
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Middle
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Good
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Low
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Mixed Coding
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SBC
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16kbps
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Good
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Middle
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RELP
|
16kbps
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Not bad
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Middle
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CELP
|
4.8~9.6kbps
|
Good
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Very complicated
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MPLPC
|
9.6~7.2kbps
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Good
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High
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Vocoder
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LPC
|
8.0~2.4kbps
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Not good
|
High
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Formant
|
0.5~1.2kbps
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Not good
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Very complicated
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