06 vdo

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06 vdo

  1. 1. ia Systems520251: Multimed Êส‹‹Çว¹น»ปÃรÐะ¡กÍอºบÁมÑัÅลµตÔิÁมÕีàเ´ดÕีÂย [ÇวÔิ´ดÕีâโÍอ] 3 ¡กÑั¹นÂยÒาÂย¹น 2555
  2. 2. TV DVD Internet VCD Streaming VDO VDO on- Chat demand e-LearningMobile It’s everywhere!!!Phone Cinema ...and Many MORE...
  3. 3. Agenda VDO Digital VDO Fundamental Production RecordProperties of Edit VDO Digital VDO Capture Formats
  4. 4. Properties of VDO
  5. 5. Analog VDO• Motion VDO was originally created and stored in analog form.
  6. 6. Digital VDO• A means of reproducing the continuous VDO waveform as a stream of digital numbers. to va rious t: im mune analogB enefi ttributed todi stor tion a ise ... such as n o
  7. 7. open wiki to Interlacing embrace the explanation!!• Interlacing was originally conceived as a way to achieve good visual quality within a limitations of a narrow bandwidth. odd field even field
  8. 8. Progressive Scanning (non-interlaced scanning)• A method of representing moving images on a display screen, in which every pixel is represented in each frame.• Computer monitors use a progressive scan.• The standard refresh rate for a flicker-free display is a vertical scan rate of 75 Hz or higher.• It’s used to project movies in theaters.
  9. 9. Notein digital TV terminology: interlaced scan is denoted by a lowercase i progressive scan is denoted by a lowercase p frame rate: (60i, 24p) resolution: (1080i, 720p)
  10. 10. Frame Rate• Frame frequency is a measure of how quickly an image device can produce unique consecutive images called frames. (expressed in frames per second - fps)• Typically, the human eye can interpret motion at 10 fps, but this rate causes a flicker effect that’s distract.• Increasing the frame rate reduces flickering.
  11. 11. Frame Rate• Movies - 14 fps• Television: • NTSC - 29.97 fps • HDTV - 60 fps• VDO games (frame rate is very important): • action-oriented games - 20-30 fps • 3D-heavy games - 90-100 fps
  12. 12. Aspect Ratios• The ratio of the width of the image to its height (w:h) • motion-picture - 1.85:1 and 2.35:1 • tv screens - 1.33:1 (aka 4:3) • HDTV - 1.78:1 (aka 16:9) 16:9 4:3 letterbox
  13. 13. Compression• VDO is huge - one sec of analog VDO stored in an uncompressed digital format takes up 1 MB of disk space • thus, 5-min VDO ~ 300 MB • not practical• VDO compression is a MUST • VDO contains many spatial and temporal redundancies • Codecs are needed for creating and viewing
  14. 14. VDO Compression• Spatial compression (intra-frame)• Temporal compression (inter-frame)• Video compression is a tradeoff between disk space, video quality, and the cost of hardware required to decompress the video in a reasonable time.
  15. 15. Spatial Compression• Just image compression applied to a sequence of images.
  16. 16. Temporal Compression• Make key frames, say every 6 frames and do the spatial compression on these frames.• Between key frames, each one of them will be replaced by a difference frame.
  17. 17. ที่มา: http://www.trustedreviews.com/camcorders/review/2007/12/22/The-Codec-Primer-Part-1/p1
  18. 18. Digital VDO File Formats
  19. 19. AVI• Most common AV data on Windows• Can be saved in a variety of compression schemes - full frames (uncompressed), Radius’s Cinepak, Intel Video, and Indeo.
  20. 20. MOV• Quicktime Movie was developed by Apple Computer• MPEG-4• Qt 7 (and later) use H.264
  21. 21. MPG• The compressed VDO file format for standard DVD using the MPEG-2 encoding standard• A large file can be transferred to MPEG with little loss of quality while dropping the bit rate a great deal
  22. 22. • The MPEG group develops the standards for encoding VDO and audio• MPEG standards: • MPEG-1: used as VCD standard (MP3 is the popular compression) • MPEG-2: use in many things such as DVD, digital satellite TV and so on • MPEG-4: support 3D content, low bit-rate encoding, support for Digital Right Management
  23. 23. Others• WMV • a part of Windows Media framework • used for streaming VDO over the internet • uses MPEG-4 standard• RM • a multimedia container with RealVideo and RealAudio codecs in a single file • is used to stream AV over the internet
  24. 24. VDO Production
  25. 25. Equipments• Digital tapeless (D)• HDV (D)• DV (formerly DVC)• 8mm (A)• VHS (A)
  26. 26. Connecting Recorder to Computer
  27. 27. Analog Camcorder
  28. 28. Coaxial• VDO and audio signals are both carries in one cable• Poorest transfer
  29. 29. A/V• Use RCA connectors• Yellow is (composite) video• Red is right audio & White is left audio
  30. 30. S-Video• Separate video - transmit VDO signals over a cable by dividing the VDO info into 2 separate signals: color (chrominance) and brightness (luminance)• Sharper than composite VDO• must be used in conjunction with audio cables
  31. 31. Digital Camcorder
  32. 32. USB• USB 2.0 are common• 480 Mbps
  33. 33. FireWire• Developed by Apple Computer• IEEE-1394 standard• 400 Mbps• higher transfer rates are available (800, 1600, and up to 3100 Mbps)
  34. 34. Transferring fromRecorder to Computer• Calculate disk space (uncompressed): • (pixel width) x (pixel height) x (color bit depth) x (fps) x (duration in secs) / 8,000,000• say, 3-min VDO @ 15 fps, 24-bit depth, 320x240 pixels will take: • (320) x (240) x (24) x (15) x (180) / 8,000,000 = 622 MB
  35. 35. VDO Editing• Editing: • cut and paste sections • add special effects • add transitions • add titles

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