1. Last updated on June 15, 2010 Doug Young Suh suh@khu.ac.kr
Media format
Last updated on June 15, 2010
Doug Young Suh
Media signal

2. Go to basics “I learned everything in Kindergarten.”
What did I learn in Kindergarten for video coding?
Probability theory, linear algebra, sampling theory

3. AD conversion Digital = discrete time + digital
Analog = continuous time + analog
Digital = discrete time + digital
Media signal

4. Sampling and human-being
Sampling theory (Nyquist theory)
Sampling frequency fs > 2fmax
Speech 8kHz > 2 X 3.2kHz
Audio kHz > 2 X 20kHz
Video
Temporal : 24Hz (movie), 60Hz (TV)
Spatial
440Hz, A, la
Low freq.
Do-Re-Mi-Pa-Sol-Ra-Si-Do
High frequency
Media signal

5. Quantization Analog digital Analog : infinite number of values
Digit-al : finite number of values
Media signal

6. Quantization and de-quantization
Loss of information, but acceptable accuracy
Media signal

7. Audio Speech: 8kHz sampling Х 8bits/sample = 64kbps 압축  10kbps
CD quality: 44kHz sampling Х 16bits/sample Х 2(stereo)
1.544Mbps  압축  128kbps or 256kbps MP3

8. Image Resolution Spatial resolution: 256*256, 8bits
Temporal resolution: 24Hz, 60Hz, etc.
(fps: frames per second)
128*128, 8bits
256*256, 4bits
Media signal

9. Color representation RGB cf) rectangular coordinate
YCbCr (YUV) cf) polar coordinate
Red (255,0,0)
Blue (0,0,255)
Media signal

10. Color representation Original Red Green Blue 4:4:4 Y U V
U, V no high freq.  4:2:2  4:2:0

11. Color conversion 1 to 1 mapping RGBYCbCr
Y = R G B
Cb = R G B
Cr = R G B
YCbCrRGB
R= Y Cr
G= Y Cb Cr
B= Y Cb
Media signal

12. Color conversion 4:4:4  1+1+1 4:2:2 Horizontally 2:1 subsampling
4:2:0 1+1/4+1/4
Most popular
Amount ½
Media signal

13. Video formats QCIF  CIF(352x288)  4CIF
QVGAVGA(640x480)SXGA(1280x1024)

14. Video encoding 2-1 2-3 2-2 DCT Q VLC IQ IDCT Original Video Encoded+
DCT Q
VLC
Encoded
Bitstream IQ
Motion
Estimation
Motion vector
Frame
Memory
IDCT
Networked Video