This standard defines a Two-Frame Marker for progressive HDTV video formats at 48/1.001(47.95)-Hz, 48-Hz, 50-Hz, 60/1.001(59.94)-Hz, and 60-Hz frame rates. This Two-Frame Marker is multiplexed into serial streams carrying such a video format to govern the alignment of system actions such as switching to the data block boundaries of embedded ancillary data services having one half the frame rate (Fr/2) compared to the video frame rate (Fr). Requirements for use of this Two-Frame Marker are also defined in this standard.

Note1: Users should be aware that equipment manufactured prior to the publication of this standard typically will not comply with its requirements.

Note2: Use of the Two-Frame Marker is optional with progressive video streams at 48/1.001(47.95)-Hz, 48-Hz, 50- Hz, 60/1.001(59.94)-Hz, and 60-Hz frame rates mapped to interlaced serial interfaces at 24/1.001(23.98)-Hz, 24- Hz, 25-Hz, 30/1.001(29.97)-Hz, and 30-Hz frame rates, respectively.

Note3: Use of the Two-Frame Marker is optional with progressive segmented frame video streams at 24/1.001(23.98)-Hz, 24-Hz, 25-Hz, 30/1.001(29.97)-Hz, and 30-Hz frame rates mapped to interlaced serial interfaces at 24/1.001(23.98)-Hz, 24-Hz, 25-Hz, 30/1.001(29.97)-Hz, and 30-Hz frame rates, respectively.