480 i component video

This chapter details the scanning, timing, sync structure, and picture structure of 480i29.97 video. The scanning and timing information in this chapter applies to all variants of 480i video, both analog and digital. The sync information relates to component analog, composite analog, and composite digital systems. 480i video represents stationary or moving two-dimensional images sampled temporally at a constant rate of 30/1.001 frames per second. A frame comprises a total of 525 horizontal raster lines of equal duration uniformly scanned top to bottom and left to right. Scanning has 2:1 interlace to form a first, as well as a second field; scan lines in the second field are displaced vertically by half the vertical sampling pitch, and delayed temporally by half the frame time, from scanning lines in the first field. To define vertical sync, the frame is divided into intervals of halfline duration. Each halfline either contains no sync information or commences with the assertion of a sync pulse having one of three durations, each having a tolerance of ±0.100 μs.