Multimedia Systems Part 13 Mahdi Vasighi www.iasbs.ac.ir/~vasighi Department of Computer Science and Information Technology, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
o Analog TV uses a continuous signal o Digital TV uses discrete numeric values Signal is sampled, and samples are quantized Why digital video? The advantages Storing video on digital devices or in memory, Direct access, which makes nonlinear video editing simple. Repeated recording without degradation of image quality. Ease of encryption and better tolerance to channel noise. The usual color space is YC b C r
Chroma Subsampling is encoding images by implementing less resolution for chroma information than for luma information. Humans see color with much less spatial resolution than black and white different schemes different names J:a:b numbers are given stating how many pixel values, per four original pixels, are actually sent. 4:4:4, 4:2:2, 4:2:1,
Chroma Subsampling 4:4:4 Each of the three YC b C r components have the same sample rate, thus there is no chroma subsampling. Y C b +C r YC b C r
Chroma Subsampling 4:2:2 2 X C b and Cr are sampled at less horizontal resolution of the luma (Y). 2 X X X Y C b +C r YC b C r ½ horizontal resolution, full vertical resolution
Chroma Subsampling 4:1:1 1 X X Cb and Cr are sampled at one quarter the horizontal resolution. 1 X X X X Y C b +C r YC b C r ¼ horizontal resolution, full vertical resolution
Chroma Subsampling 4:2:0 2 X X X C b and Cr are sampled at both half the horizontal and vertical resolution of the luma (Y). 0 X X X Y C b +C r YC b C r ½ horizontal resolution, ½ vertical resolution
Chroma Subsampling 4:2:0 C b and Cr are sampled at both half the horizontal and vertical resolution of the luma (Y).
Compression Artifacts it will be most visible near the edges of sharp color transitions. 4:4:4 4:2:2 4:2:0 4:1:1
A full frame of interlaced video consists of two almost identical fields (Odds and Evens lines). A field is made up of three distinct regions, first blanking period, active video and second blanking period. A complete NTSC/PAL video frame Lines Field / VBlk PAL NTSC F V Line Description 22 19 '0' '1' Field 1 - First Vertical Blanking (Top) 288 240 '0' '0' Field 1 - Active Video 2 3 '0' '1' Field 1 - Second Vertical Blanking (Bottom) 23 20 '1' '1' Field 2 - First Vertical Blanking (Top) 288 240 '1' '0' Field 2 - Active Video 2 3 '1' '1' Field 2 - Second Vertical Blanking (Bottom) 625 525
Lines consist of four parts, EAV Code, Blanking Video, SAV Code and Active Video.
Example 1: Resolution 720x485, frame rate 30 frames per sec (fps) 720x485 = 349,200 pixels/frame 4:4:4 sampling gives 720x485X3=1,047,600 bytes/frame 30fps 1.05Mx30=31.5MBytes/sec 31.5Mx8bits=250Mbps 4:2:2 subsampling gives 720x485x2=698,400 bytes/frame 30fps 0.698x30=21 MB/sec 21Mx8=168Mbps
Example 2: Resolution 1280x720, frame rate 30fps 1280x720 = 921,600 pixels/frame 4:2:0 subsampling gives 921,600x1.5=1,382,400 bytes/frame 30fps 1.38Mx30=41MB/sec 41x8=328Mbps (656Mbps 4:4:4) Example 3 Resolution 1080x1920, frame rate 60fps 1080x1920 = 2,073,600 pixels per frame 4:4:4 sampling = 2,073,600x3 = 6,220,800 bytes/frame 60fps 2,073,600x60 = 373,248,000 bytes per second 374MB/s = 374Mx8=3Gbps Conclusion: Compressing Digital Video!!!
CCIR (Consultative Committee for International Radio) standards CIF stands for Common Intermediate Format VHS quality, is to specify a format for lower bitrate
The Advanced Television Standards Committee (ATSC) has set voluntary standards for digital television: how sound and video are encoded and transmitted. guidelines for different levels of quality lowest quality digital format is about the same as the highest quality an analog TV can display.
HD ready vs. Full HD
Ultra High Definition TV UHDTV is a new development (a new generation of HDTV!) The standards announced in 2012 4K UHDTV: 2160P ( 3840 2160, progressive scan) 8K UHDTV: 4320P ( 7680 4320, progressive scan) aspect ratio is 16:9 bit-depth can be up to 12 bits chroma subsampling can be 4:2:0 or 4:2:2.
Digital Video
3D Video and TV 3D Movie Using Colored Glasses (Anaglyph 3D)
3D Video and TV 3D Movies Using Circularly Polarized Glasses
3D Video and TV