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MPEG: A Video Compression Standard for Multimedia Applications Didler Le Gall

MPEG: A Video Compression Standard for Multimedia Applications Didler Le Gall. Goals. Reduce the high cost of video compression codecs Resolve the critical problem of interoperability of equipment from different manufacturers Come up with a standard within 2 years. MPEG.

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MPEG: A Video Compression Standard for Multimedia Applications Didler Le Gall

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  1. MPEG:A Video Compression Standardfor Multimedia ApplicationsDidler Le Gall

  2. Goals • Reduce the high cost of video compression codecs • Resolve the critical problem of interoperability of equipment from different manufacturers • Come up with a standard within 2 years

  3. MPEG • Stands for Moving Picture Experts Group (ISO-IEC) • Started in 1988 • Had to come up with a draft of the standard by 1990 • Received MPEG Proposal from mostly commercial companies

  4. MPEG (cont’d) • MPEG-Video • MPEG-Audio • MPEG-System • Synchronization of audio and video

  5. Requirements • A Generic Standard • Random Access • Fast Forward/Reverse Searches • Reverse Playback • Audio Visual Synchronization • Robustness to Errors

  6. Requirements (cont’d) • Coding/Decoding Delay • Editability • Format Flexibility • Cost Tradeoffs

  7. MPEG-VIDEO Compression • Spacial Redundancy • Intraframe compression • DCT compression • Temporal Redundancy (i.e. motion compression) • Interframe compression

  8. 120 108 90 75 69 73 82 89 127 115 97 81 75 79 88 95 134 122 105 89 83 87 96 103 137 125 107 92 86 90 99 106 131 119 101 86 80 83 93 100 117 105 87 72 65 69 78 85 100 88 70 55 49 53 62 69 89 77 59 44 38 42 51 58 Discrete Cosine Transform (DCT) 0 – black 255 – white

  9. DCT (cont’d) • The 64 (8 x 8) DCT basis functions • Superimpose multiples of these functions to simulate the original picture

  10. 700 90 100 0 0 0 0 0 90 0 0 0 0 0 0 0 -89 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DCT (cont’d) 0 – black 255 – white

  11. 700 90 100 0 0 0 0 0 90 0 0 0 0 0 0 0 -89 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DCT (cont’d) 700 90 90 -89 0 100 0 0 0 .... 0

  12. Motion Compensation • I-Frame • Independently reconstructed • P-Frame • Forward predicted from the last I-Frame or P-Frame • B-Frame • forward predicted and backward predicted from the last/next I-frame or P-frame Transmitted as - I P B B B P B B B

  13. Motion Prediction

  14. Motion Estimation

  15. Motion Estimation (cont’d)

  16. Conclusion • Video quality better than VHS can be achieved with a bit rate of about 1.5 Mbits/s • Does not handle higher resolution with small bit rate

  17. References • MPEG Notes by Dale Kolosna • MPEG Compression Technique (http://rnvs.informatik.tu-chemnitz.de/~jan/MPEG/HTML/mpeg_tech.html)

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