SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Ancillary data appearing in horizontal blanking is called Horizontal Blanking Ancillary Data. Ancillary Data in vertical blanking is called Vertical Blanking Ancillary Data.
Horizontal Blanking Ancillary Data is not commonly used. For the ACTVID data valid mode described in Figure 9-31, there is no way to capture Horizontal Blanking Ancillary Data. Using the HSYNC mode in Figure 9-33, all blanking pixels are captured. However, the horizontal ancillary data is byte-by-byte distributed between the Luma and Chroma frame buffers. Chroma sited bytes are saved in the Chroma frame buffer and Luma sited bytes are saved in the Luma frtame buffer. Some CPU effort would be needed in order to extract ancillary data from the desired Luma or Chroma channel frame buffers. Also, the video on each line starts after the horizontal blanking period. This situation is shown in Figure 9-40.
With Interlaced source material, Vertical Blanking Ancillary data will be stored in a separate Vertical Ancillary Data Buffer as shown in Figure 9-41. The Channel from which vertical ancillary data is extracted is a configuration option. For an input image of x active pixels per line, each line of Vertical Blanking Ancillary Data will have x bytes. Unlike the horizontal case, the CPU parsing this Ancillary Data will see a contiguous section of Vertical Ancillary Data that is not intermixed with Video data.
For Progressive source video, the FIELD ID does not change. So, the Vertical Ancillary Data Buffer will contain all the information beginning from the vertical blanking of the previous frame. This situation is shown in Figure 9-42.