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By Max Havir

By Max Havir. MPEG1 MPEG2 MPEG4 MPEG7 MPEG21 Cinepak. Motion JPEG A Motion JPEG B H.261 H.263 Sorenson Video Divx. Video Compression. How Does Video Compression Work?. Process of MPEG Compression. Translate into a YUV scale YUV sample ratio Discrete cosine transformation

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By Max Havir

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  1. By Max Havir

  2. MPEG1 MPEG2 MPEG4 MPEG7 MPEG21 Cinepak Motion JPEG A Motion JPEG B H.261 H.263 Sorenson Video Divx Video Compression

  3. How Does Video Compression Work?

  4. Process of MPEG Compression • Translate into a YUV scale • YUV sample ratio • Discrete cosine transformation • Quantization • Runlength encoding • Interframe compression

  5. YUV (YCrCb) Color

  6. Color Sub-sampling

  7. Discrete Cosine Transformation • DCT's (discrete cosine transforms) to organize the redundancy in the spatial directions • Looks at the current frame and attempts to detect correlation within the image. • The DCT does not actually do any compression, but the coefficients can be used in later steps.

  8. Quantization • The DCT coefficients are quantized into finite values. The less number of values the lower the quality will be.

  9. Run Length Encoding • 8, 4, 4, 2, 2, 2, 1, 1, 1, 1, (12 zeroes), 1, (41 zeroes) • Code values are given based on the probability of occurrence.

  10. I-Frame, P-Frame, B-Frame

  11. MPEG1 vs. MPEG2

  12. Profiles in MPEG2 MPEG 2 offers profiles that allow its use in a wider range of applications

  13. MPEG4 MPEG-4 will allow ‘universal access’ to multimedia information, by taking into account specificities of a wide variety of networks • Video rates ( as claimed by creators) • low (<64 kbps), • intermediate (64-384kbps), and • high (384-4Mbps) bitrates.

  14. H.261 and H.263 • Designed for low data rates(<50Kbps) and video- conferencing

  15. Sources • http://www.compressionworks.com • http://members.aol.com/symbandgrl/ • http://bmrc.berkeley.edu/frame/research/mpeg/ • http://www.apl.jhu.edu/Notes/Geckle/525759/lecture10.pdf • www.mpeg.org • http://mpeg.telecomitalialab.com/

  16. Sources (cont.) • http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/2-overview_paper/2-overview_paper.htm • http://www-mobile.ecs.soton.ac.uk/peter/h263/h263.html

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