SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The VIP/VPDMA support Frame Buffers in DDR memory for Active Video and Ancillary Data.
4:2:2 data is always saved in packed pixel buffers.
4:2:0 data is saved in Planar Luma buffers and Planar CbCr pair buffers.
A Luma Frame Buffer is a Planar storage area. Each line is the width in pixels (1Byte/pixel) of the output picture size format. The frame buffer contains the number of active video lines in the output picture size format.
A Chroma Pair Frame Buffer is Planar storage of CbCr pixel pairs, with each pixel being a byte. For 4:2:0 storage, N lines in the output picture active video results in N/2 lines of CbCr pairs being stored.
The Ancillary Data buffer is different than the Active Video Frame Buffers. The Ancillary Data buffer only stores Vertical Blanking Ancillary Data. The number of lines in the Ancillary Data buffer is the same as the number of Vertical Blanking lines. Typically, only one channel is extracted from the Vertical Blanking data, so the width of the Ancillary Data buffer is the same as the width of the Luma Buffer.
In 8-bit input mode, it is possible for both Luma and Chroma sites to be extracted for Vertical Ancillary data. Each color component is strobed on separate input clock cycles. In this case, the line width of the Ancillary data is twice the Luma line width of the picture. Both Luma and Chroma sites cannot be extracted for 16-bit input mode because both Luma and Chroma are sent on the same input clock cycle and the Ancillary port to the VPDMA VPI is only 8 bits wide.
Figure 11-22 shows how the planar data regions are stored in DDR memory. The vertical blanking data is stored in a set of Planar Buffers. Note that the bottom of the Vertical Ancillary Data from the previous field or frame is stored in the same buffer as the top of the Vertical Ancillary Data from the current field or frame.
The Luma representing Active Video is stored in a set of Planar Buffers. The CbCr Chroma Pairs are stored in a set of Planar Buffers.