Table 3 of the ATSC DTV Standard, Annex A, summarizes the picture formats originally allowable for DTV transmission in the USA. Any one of these may be compressed using MPEG-2 and transmitted. An ATSC receiver must be able to display pictures from any of these formats.
The range of formats in Table 3 caters for schemes familiar to both television and computers, and takes account of different resolutions, scanning techniques and refresh rates. For each frame size, frame rates are available to provide compatibility with existing transmission systems and receivers. 29.97 Hz is needed to keep step with NTSC simulcasts. Technically this is not required once NTSC is no longer transmitted! 30 Hz is easier to use, and does not involve considerations such as drop-frame timecode. 24 Hz progressive (24P) offers compatibility with film material. A choice of progressive or interlaced scanning is also available for most frame sizes (see Progressive and Interlaced).
Table 3 is concerned with video formats to be handled in the ATSC system rather than defining standards for video production. ATSC’s Table 1 of annex A refers to the standardized video production formats likely to be used as inputs to the compression table.
|Vertical size value||Horizontal size value||Aspect ratio information||Frame rate code||Progressive sequence|
Video standard Active lines Active samples/line
SMPTE 274M 1080 1920
SMPTE S17.392 720 1280
ITU-R BT.601-4 483 720
ATSC Annex A, Table 1: Standardized video input formats
|Video standard||Active lines||Active samples/line|