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Kommunikatsiooniteenuste arendus IRT0080

Kommunikatsiooniteenuste arendus IRT0080. Loeng 3/2008 Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst. avo.ots@ttu.ee. ^. X. X. X. Encoder. Decoder. Source coding. Source alphabet Distribution Reconstruction alphabet Distortion measure

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Kommunikatsiooniteenuste arendus IRT0080

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  1. Kommunikatsiooniteenuste arendusIRT0080 Loeng 3/2008 Avo Otstelekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst.avo.ots@ttu.ee

  2. ^ X X X Encoder Decoder Source coding Source alphabet Distribution Reconstruction alphabet Distortion measure Distortion constraint D: Encoder: Decoder Minimum rate of representing X with distortion D: Rate-distortion function R(D)=

  3. TV standardid Videoriba laius 5.0 MHz (6,0 MHz) • NTS C 525 rida (262.5 rida)60 kaadrit sekundis. Reasagedus fh= 15750 Hz • Euroopa: 625 rida, (312.5 rida)50 kaadrit sekundisReasagedus fh= 15625 Hz • HDTV: kaadri formaat 16:9 • 720p (1280 x 720 pildipunkti (pikselit)) • 1080i (1920 x 1080 pildipunkti)

  4. Üks rida kujutisest How many lines?

  5. Television  Digital Video • Broadcast Television (analog) • movie at home - why invent new technology? • mass market • influence of movie on development • Key Steps • convert pictures to electric signal • send electric signal • convert electric signal to picture • Comparison with motion picture • High Definition Television - analog  digital, compression • Video conference - travel cost, people cost

  6. Broadcast Television • Convert picture to electric signal – video camera • initially only at TV studios, cost not as important • recording media, editing, … • special equipment to convert movie • Send electric signal • follow radio broadcast, needs spectrum allocation from • Convert electrical signal to picture _cathode ray tube _flat panel: LCD, LED, plasma

  7. Värvuse ülekanne Y=0.587 G + 0.299 R + 0.114 BHeledussignaal. Ühildavus monokroomsega U=0.493 (B-Y) V=0.877 (R-Y) PAL f=4.433619 Hz

  8. Analoog kompo-siit väljund (PAL) Y U V G B R Optilinesõlm ja video-muundur maatriks Komposiitkooder G B R Y U V Optilinesõlm ja video-muundur Tele-programmivalmis-tamine maatriks A/D MPEGkooder Digi-taalnepakitudväljund SDI Analoog/digitaal video

  9. Digitaliseerimine Komponentide ribalaius kuni 6 MHz Diskreetimissagedus fd= 13.5 MHz • fd= 864 fh NTSC (Põhja-Ameerika) • fd= 858 fh PAL (Euroopa) Kvanteerimine 8 bitti => 13.5* 8 =108 Mbps Standard ITU-R BT.601 => 720 pildipunkti reas 4 : 2 : 2 => 216 Mbps

  10. Analoogvideo digitaalseks • Digivideo standard ITU-R BT.601-5, standardi järgi on kaadri suurus 720x576 (PAL jaoks). • Ei tarvitse olla 720 pikselit reas. Video digitaliseerimiseks võetav pikselite arv ei pea vastama kuvamise seadme pikselite arvule • PAL formaadis saab digivideot esitada erinevatel kaadri suurustel 720x480 või 720x576.

  11. Digivideo vormingud ITU-R-601 720x480 4:2:2 CIF 360x288 4:2:0 4:3 HDTV 1440x1152 4:2:2, 4:2:0 9:16 HDTV 1920x1152 4:2:2, 4:2:0 4CIF, 16CIF, QCIF

  12. YUV paralleelselt Y U V Maat-riks 10 bitti 27 MHz 13,5 MHz 6,75 MHz takt RGB Kaamera Digivideosignaal

  13. Heliressursi vajadus on suurusjärk väiksem kujutisega võrreldes (stereoheli kõrgtase 192+192 kbit/s) Video kodeerimine standardid edastuskiirustele 1,5…60 Mb/s; MP@ML15 Mb/s on tavaline(“Main Profile at Main Level”) VideoPES Programmi voo MUX Video andmed Video kooder Pakett Programmi voog (DVD) Audio andmed AudioPES Audio kooder Pakett Üksiku programmitranspordivoog Transpordi voo MUX Elementide voog Andmed Video ja heli PES – programmi elementide voog

  14. Kujutisest signaal

  15. Signaali (heledus) esitus U T= 1 (ajaühik) t T0 T1 f 0 1 3 5

  16. Heledusastmed 11 10 01 00

  17. Kujutis läbi madalpääsfiltri

  18. Kujutis läbi kõrgpääsfiltri

  19. macroblock Y1 Y2 U1 V1 Y3 Y4 U2 V2 Y1 Y2 V U Y3 Y4 DV plokid • 4:2:2 YUV • 16x16 macroblock • 8x8 pixel blocks • 8 bits/sample = 16 bits/pixel = 4Kbits/macroblock • 4:1:1 YUV • 3Kbits/macroblock • 12 bits/pixel • 30 fps * 720 * 480 * 1.5 * 8 = 124 Mb/s • 9:16 HDTV • 30 fps * 1920 * 1152 * 1.5 * 8 = 796Mb/s

  20. Color Space Conversion • RGB to YUV or (YCrCb) • Y luminance component (brightness). Y = 0.299 R + 0.587 G + 0.144 B • U, V U = B – Y V = R - Y Y U V

  21. Image block DCT Coefficients

  22. Kahemõõtmeline kujutis

  23. Ruumiline “aeg” 1 0 1 0 0 1 0 1 1 0 1 0 0 1 0 1

  24. Ruumiline “sagedus” 0.5 0.7 0.2 0.05 0.6 0.5 0.07 0 0.1 0.08 0.01 0 0.01 0 0 0

  25. JPEG 8x8 block DCT Quantization Quantization tables Header DC Entropy coding Tables Difference coding Data Run length coding AC

  26. Makroblokk (8 * 8)

  27. Koosinusteisendatud ,

  28. JPEG 2000 Features • Improved compression efficiency (vs. JPEG) • Highly scalable embedded data streams • Progressive lossy to lossless compression within a single data stream • Arbitrarily crop images in the compressed domain • Selectively enhance quality of spatial “regions of interest” • Support for very large images

  29. Liikuva kujutise edastusvariandid

  30. Lõpulingid http://en.wikipedia.org/wiki/Source_coding http://www.chiariglione.org/mpeg/ http://www.jpeg.org/jpeg2000/ http://en.wikipedia.org/wiki/YUV http://www.iec.ch/ http://www.itu.int/rec/R-REC-BT.601/en http://www.ebu.ch/ http://en.wikipedia.org/wiki/Video_codec

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