0 SAMPLE 0 DATA 4 SAMPLE 4 DATA - 1 SAMPLE 1 DATA 2 SAMPLE 2 DATA Figure 7.2-6 4:1:1 Frame Buffer Formatting. 3 SAMPLE 3 DATA -4 SAMPLE 4 DATA Figure 7.2-4 4:2:2 Frame Buffer Formatting. xvYCC Color space 4:2:0 YCbCr Format The xvYCC (extended gamut YCbCr for video) color space extends the color gamut of normal YCbCr, Rather than the horizontal-only 2:1 reduction of Cb and enabling 1.8x more colors to be reproduced. The spec- Cr used by 4:2:2, 4:2:0 YCbCr implements a 2:1 re- ification for xvYCC (IEC 61966-2-4) uses BT.709 duction of Cb and Cr in both the vertical and horizontal chromaticity and D65 reference white. The equations for directions. It is commonly used for video compression. converting between scR'G'B' and xvYCbCr are the same As shown in Figures 7.2-7 through 7.2-11, there are as those used for converting between R'G'B' and YCbCr. several 4:2:0 sampling formats. Table 7.2-3 lists the xvYCC-based YCbCr data has an 8-bit range of YCbCr formats for various DV applications. 1-254, enabling backwards compatibility with existing To display 4:2:0 YCbCr data, it is first converted to designs. Y has an 8-bit range of - -15/219 to +238/219 4:4:4 YCbCr data, using interpolation to generate the (-0.068493 to +1.086758); CbCr has an 8-bit range of new Cb and Cr samples. Note that some solutions do not - 15/224 to +238/224 (-0.066964 to +1.062500). properly convert the 4:2:0 YCbCr data to the 4:4:4 HDMI uses Gamut Boundary Description metadata to format, resulting in a "chroma bug." convey xvYCC video data is being used. ACTIVE ACTIVE X = FIELD 1 (576i FIELD 2) [X] = FIELD 2 (576i FIELD 1) NUMBER NUMBER CALCULATED CB, CR SAMPLE CB, CR SAMPLE Y SAMPLE Y SAMPLE Figure 7.2-7 4:2:0 Sampling for H.261, H.263, and MPEG-1. The Figure 7.2-5 4:1:1 Co-Sited Sampling. The sampling positions sampling positions on the active scan lines of a progressive or on the active scan lines of an interlaced picture. noninterlaced picture. Colour spaces CHAPTER 7.2 ACTIVE ACTIVE FIELD N FIELD 1 NUMBER NUMBER CALCULATED CB, CR SAMPLE Y SA