Video Media Department of Computer Education KMUTNB

Video Media Multimedia Video features in a range of Multimedia application Entertainment –Broadcast television and VCR/DVD recordings Interpersonal –Video telephony and videoconferencing Interactive –Windows containing short video clips

Video Media Multimedia Broadcast Television 525 Lines –NTSC American standard –60 Fields / second –30 Frames / second 625 Lines –PAL European standard /CCIR/SECAM –50 Fields / second –25 Frames / second

Video Media Multimedia Scanning illustrated Time Voltage Sample 720 pixel

Video Media Multimedia Type of Scanning Progressive = every scan line done in turn. Interlaced = every other scan line done. –Creates two fields: odd field and even field. –NTSC: lines per field at 60 fields per sec. –PAL: lines per field at 50 fields per sec. Fields are separated in time.

Video Media Multimedia Computer & TV 1 TV Frame = 2 Field interlaced scan 1 Computer Frame Progressive scan

Video Media Multimedia Computer & TV Television Computer 1 Frame … ……. … … …… 62 4 …… Even Field Odd Field

Video Media Multimedia Video capture with both field Computer … ……. … … …… 62 4 …… Even Field Odd Field TelevisionComputer … ……. …..

Video Media Multimedia Video capture with one field Computer …. ……. … … …… 62 4 …… Even Field Odd Field Television Discard MPEG 1 ( VCD) From Interlaced to Progressive system discard resolution in half

Video Media Multimedia Scanning Sequence in TV Interlaced scanning principles

Video Media Multimedia Scanning Sequence in TV 525-line systems : each field, 240 visible 625-line systems : each field, 288 visible

Safe Frame From Camera View Finder To TV To Digital File

Video Media Multimedia Broadcast Television Video resolution and quality

Video Media Multimedia 3 Main Properties of a Color Hue: The actual color of the source, each color has a different frequency/wavelength and eye determines the color from this. Saturation: The strength of vividness of the color, a pastel color has a lower level of saturation than a color such as red. Brightness : The amount of energy that stimulates the eye and varies on a gray scale from black (lowest) Through to white(highest)

Video Media Multimedia Luminance & Chrominance Luminance : is used to refer to the brightness of a source, and the hue and saturation Chrominance: is used to refer to the color characteristics.

Video Media Multimedia TV Color Signals Component Signal Luminance Chrominance Traditional monochrome TV White --> Black Magnitude of the 3 electrical signals that energize the R,G,B Phosphors 0.299R G B

Video Media Multimedia Composite Video Signals Ys = Rs Gs Bs Cr = Rs - Ys Cb = Bs - Ys Ys is amplitude of luminance signal Rs, Gs, Bs is magnitude of 3 color component signals

Video Media Multimedia Composite Video Signals RGBRGB Cr Ys Cb - Rs Gs Bs monochrome + + Composite Video Signal

Video Media Multimedia Chrominance components From Ys, Cr, Cb PAL : Y = R G B U = (B - Y) V = (R - Y) NTSC : Y = R G B I = 0.74 (R-Y) (B-Y) Q = 0.48 (R-Y) (B-Y)

Video Media Multimedia Signal bandwidth Baseband spectrum of color television signals in NTSC system NTSC : Y = 4.2 MHz I = 2 MHz Q = 1 MHz

Video Media Multimedia Signal bandwidth Baseband spectrum of color television signals in PAL system PAL : Y = 5.5 MHz U = 3 MHz V = 3 MHz

Multimedia Summary Multimedia Digital Video Frames Almost always progressive 3 planes of pixel values (Y, U, and V) Pixel depth Geometry of each plane: width x height –Chrominance is generally subsampled.

Video Media Multimedia Digital video The visual perception of the eye have less sensitive for color than luminance This means that 2 chrominance signals can tolerate a reduced resolution relative to that used for the luminance signal Saving in terms of resulting bit rate and transmission bandwidth

Video Media Multimedia Digital video standard International Telecommunications Union Radiocommunications Branch (ITU-R) Formerly known as the Consultative Committee for International Radiocommunications (CCIR) Recommendation CCIR-601

Video Media Multimedia CCIR-601 Standard established for digitizing NTSC and PAL signals Digital Component Analog Counterpart CCIR-601 Recommendation HeightLinesNTSC: 480 PAL: 576 WidthContinuous voltage changes along scan line. Sample at 13.5 MHz Results in 702 pixels Recommended 720 Pixel depthVoltage range.Gamma-corrected 8-bit sample. Chrominance subsampling Bandwidth differences 4:2:2, 4:2:0, 4:1:1

, 4 1, 3 1, 2 Video Media Multimedia Video Color Storing Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 The visual perception of the eye have less sensitive for color than luminance From SourceStoring method

, 4 1, 3 1, 2 Video Media Multimedia Video Color Playback Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 1 3, 1 3, 2 3, 3 3, 4 Cr,Cb Playback process

Video Media Multimedia Video Digitization Formats  4:2:2 means 2:1 horizontal downsampling, no vertical downsampling. (Think 4 Y samples for every 2 Cb and 2 Cr samples in a scanline.)  4:1:1 ought to mean 4:1 horizontal downsampling, no vertical. (Think 4 Y samples for every 1 Cb and 1 Cr samples in a scanline.) It is often misused to mean the same as 4:2:0.  4:2:0 means 2:1 horizontal and 2:1 vertical downsampling. (Think 4 Y samples for every Cb and Cr samples in a scanline.)

Video Media Multimedia 4:2:2 Use in television Studio For every 4 luminance samples, take 2 chrominance samples from odd lines and 2 from even lines. Chrom. planes just as tall, half as wide. JPEG does this.

Video Media Multimedia 4:2:2 Sample positions with 4:2:2 digitization format

Video Media Multimedia 4:2:2 Sample positions with 4:2:2 digitization format 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 From SourceStoring method Every 4 pixel Keep 2 odd Keep 2 even Storage size Y+Cr+CbStorage size Y+0.5Cr+0.5Cb

Video Media Multimedia 4:2:0 Used in Digital Video broadcast application 2 chrominance samples for every 4 luminance samples, odd lines only. Chrominance halved in both directions. MPEG generally does this.

Video Media Multimedia 4:2:0 Sample positions with 4:2:0 digitization format

Video Media Multimedia 4:2:0 Sample positions with 4:2:0 digitization format 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 From SourceStoring method Every 4 pixel Keep 2 odd Keep 0 even Storage size Y+Cr+CbStorage size Y+0.25Cr+0.25Cb

Video Media Multimedia 4:2:0 4:2:0 playback process 1, 2 Y Cr Cb 1, 1 2, 2 2, 1 1, 2 Y Cr Cb 1, 1 2, 2 2, 1 Play

Video Media Multimedia 4:2:0 To avoid flicker effect with the chrominance signal –the receiver uses the same chrominance value from the sampled lines for the misslines Large-screen flicker effects are often reduced by –storing the incoming digitized signals of each field in a memory buffer –Double the normal rate 100/120 Hz then used with the stored set of signals used for the 2 field

Video Media Multimedia HDTV High-Definition Television Older 4/3 aspect ratio 1440 x 1152 pixels newer 16/9 aspect ratio 1920 x 1152 pixels 1080 visible lines per frame 4:2:2 digitization for studio application –Frame rate 50/60 Hz 4:2:0 digitization for broadcast application –Frame rate 25/30 Hz

Video Media Multimedia SIF Source Intermediate Format Used in Video Cassette Recorders (VCR) Used Half spatial resolution in both horizontal and vertical in 4:2:0 format Frame rate 30 Hz for 525 line, 25 Hz for 625 line Progressive (non interlaced) scanning The receiver estimated by interpolating between each pair of value missing line

Video Media Multimedia SIF and CIF Sample positions for SIF and CIF

Video Media Multimedia SIF and CIF Sample positions with 4:2:0 digitization format 1, 4 1, 3 1, 2 Y Cr Cb 1, 1 2, 4 2, 3 2, 2 2, 1 3, 4 3, 3 3, 2 3, 1 4, 4 4, 3 4, 2 4, 1 1, 3 Y 1, 1 3, 3 3, 1 From SourceStoring method Storage size Y+Cr+CbStorage size 0.25Y Cr Cb Cr Cb 2, 2

Video Media Multimedia SIF and CIF Sample positions with 4:2:0 digitization format 1, 3 1, 1 Y Cr All 2,2 Cb All 2,2 1, 1 1, 3 1, 1 3, 3 3, 1 3, 3 3, 1 Playback 1, 3 Y 1, 1 3, 3 3, 1 Storing method Cr Cb 2, 2

Video Media Multimedia When Capture from Video Tape Sample positions with 4:2:0 digitization format 1, 3 Y 1, 1 3, 3 3, 1 From Video Tape or Home use Quality Signal 2, 2 1, 3 Y Cr Cb 1, 1 3, 3 3, 1 Capture to Computer 360x288 Video Tape Video Clip

Video Media Multimedia CIF Common Intermediate Format Defined for use in Videoconferencing applications Typical bit rate used is a single 64 kbps ISDN channel Can multiple channel for high bit rate 4CIF: Y= 720 x 576 Cb = Cr = 360 x CIF: Y= 1440 x 1152 Cb = Cr = 720 x 576

Video Media Multimedia CIF 64 kbps CIF 64 kbps 360x288 CIF 720x576 CIF 256 kbps 64 kbps In Videoconference Application

Video Media Multimedia Common Digital Video Sizes CCIR x4804:2:2, 4:2:0 SIF360x2404:2:0 CIF360x2884:2:0 4:3 HDTV1440x11524:2:2, 4:2:0 9:16 HDTV1920x11524:2:2, 4:2:0 4CIF, 16CIF, QCIF

Video Media Multimedia PC video digitization formats

Video Media Multimedia Multimedia Communication Standards H.320 Video Teleconferencing Standard –Visual Telephone System over N-ISDN H.324 –low bit rate multimedia communication terminal for PSTN and Mobile Radio H.321, H.310 –high resolution broadband audiovisual communication systems via B-ISDN H.322, H.323 –narrowband visual telephone services on LAN

Video Media Multimedia Referrence Multimedia communication Application, Networks, protocols and standards; fred halsall. Chapter 2 Multimedia information representation page ; ISBN html