The color-difference signals’ sampling frequency is 37.25MHz or 1100 x fH. The specified anti-aliasing low-pass filter has a cutoff frequency of 30MHz. This results in a Nyquist frequency of 37.125MHz. The luminance sampling frequency of 74.25MHz is obtained from the analog input video sync signal using a PLLC oscillator operating at 2200 x fH. The implication here is that format conversion applications require matrixing recalculation. The coded signals’ matrix coefficients are defined in ITU-R BT.709 and are significantly different from those specified by ITU-R BT.601. This article will deal with some aspects of the 1920x1080/60i format using E´Y, E´CB and E´CR analog source signals. The digital coding is based on one luminance (E´Y) and two color-difference (E´CB and E´CR) analog signals, or on the use of the three primary analog signals – E´G, E´B and E´R. The reader is referred to the relevant SMPTE or ITU standard for details. The analog sync signals are not digitized, so they are rarely, if ever, encountered in practice. It is interesting to note that this format uses analog sync signals that differ from those used by SDTV formats. The horizontal scanning frequency is 33750Hz. Field 1 has 563 lines and Field 2 has 562 lines.

As a consequence, the interlace versions define integer, and hence unequal, numbers of lines in each of the two fields comprising a frame. This permits the unambiguous identification of the lines by the digital timing reference sequences (TRS). However, because a digital interface has to be supported, only whole numbers of lines in each field are allowed. In an analog system this would imply 562.5 lines in each field.

There are a total of 1125 lines per frame. Each frame consists of two interlaced fields with an interlace ratio of 2:1, resulting in a field rate of 60Hz, or 60/1.001Hz for NTSC-friendly applications. Table 1 shows that the 1920x1080/60i format has a nominal frame rate of 30Hz or 30/1.001Hz (NTSC-friendly). Picture scanning characteristics of the 1920x1080/60i format are listed above.

1920x1080 f1 2019 images