media signal media format last updated on june 15, 2010 doug young suh suh@khu.ac.kr

Media signal

Media format

Last updated on June 15, 2010

Doug Young Suhsuh@khu.ac.kr

Go to basics“I learned everything in Kindergarten.”

What did I learn in Kindergarten for video coding?

• Probability theory, linear algebra, sampling theory

Media signal

AD conversion

Analog = continuous time + analog

Digital = discrete time + digital

Media signal

Sampling and human-being

Low freq.

High frequency

440Hz, A, Ra

Do-Re-Mi-Pa-Sol-Ra-Si-Do

Media signal

Quantization

Analog digital

Analog : infinite number of valuesDigit-al : finite number of values

Media signal

Quantization and de-quantization

Loss of information, but acceptable accuracy

Media signal

Image Resolution

Original image :256*256, 8bits

128*128, 8bits

256*256, 4bits

Media signal

Color representation

CameraLinearMatrix

A to DConverter

G

R

B

C b

Y

C r

RGB cf) rectangular coordinate

YCbCr (YUV) cf) polar coordinate

Red (255,0,0)

Blue (0,0,255)

Original Red Green Blue 4:4:4

Y U V

U, V no high freq. 4:2:2 4:2:0

Color representation

Media signal

RGBYCbCr Y = 0.29900R+0.58700G+0.11400B Cb = -0.16874R-0.33126G+0.50000B Cr = 0.50000R-0.41869G-0.08131B

YCbCrRGB R=1.00000Y+1.40200Cr G=1.00000Y-0.34414Cb-0.71414Cr B=1.00000Y+1.77200Cb

Color conversion 1 to 1 mapping

Media signal

Color conversion 4:4:4 1+1+1

4:2:2Horizontally 2:1 subsampling

4:2:0 1+1/4+1/4

Most popular Amount ½

Video formats

QCIF CIF(352x288) 4CIF QVGAVGA(640x480)SXGA(1280x1024)

Networked Video

VLCQ DCT

MotionEstimation

+

FrameMemory

Original Video

Encoded Bitstream

Video encoding

IQ

IDCT

Motion vector

2-3 2-22-1