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Understanding Media Signal Processing: Basics of Quantization, Sampling, and Video Formats

This document outlines the foundational concepts of media signal processing, encompassing critical areas such as quantization, sampling theory, and format standards. It explores fundamental principles learned at an elementary level, linking them to advanced topics like probability, linear algebra, and audio/video encoding techniques. Key theories such as Nyquist sampling frequency and quantization effects on image resolution are discussed, along with color representation and conversion between RGB and YCbCr formats. Additionally, it covers various video formats and essential encoding techniques.

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Understanding Media Signal Processing: Basics of Quantization, Sampling, and Video Formats

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  1. Media format Last updated on June 15, 2010 Doug Young Suh suh@khu.ac.kr 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 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 44.1kHz > 2 X 20kHz • Video • Temporal : 24Hz (movie), 60Hz (TV) • Spatial 440Hz, A, Ra 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. Image Resolution • Original image :256*256, 8bits 128*128, 8bits 256*256, 4bits Media signal

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

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

  10. Color conversion • 1 to 1 mapping • RGBYCbCr • Y = 0.29900R+0.58700G+0.11400B • Cb = -0.16874R-0.33126G+0.50000B • Cr = 0.50000R-0.41869G-0.08131B • YCbCrRGB • R=1.00000Y+1.40200Cr • G=1.00000Y-0.34414Cb-0.71414Cr • B=1.00000Y+1.77200Cb Media signal

  11. 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

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

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

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