SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The necessary minimum buffer size depends on the SDRAM prefetch size and on initiator support in terms of the following:
Let N be the maximum number of elements per line for a given mode (element size) and orientation, P be the SDRAM memory prefetch size in bytes, and max be the function returning the maximum of the two parameters. The minimum necessary line buffer size to handle all resolutions in a given mode and orientation is listed in Table 15-17.
0- or 180- Degree Orientation (S = 0) | 90- or 270-Degree Orientation (S = 1) | |
---|---|---|
8-bit mode | 4 × N bytes | max (4,P/4) × N bytes |
16-bit mode | None | max (8,P/2) × N bytes |
32-bit mode | None | max (8,P/2) × N bytes |
This minimal buffer size can be reached only with an advanced FIFO management scheme. The standard ping-pong buffer requires twice this buffer size.
Given their nature, field accesses to an interlaced frame-buffer require buffers twice as small as in the standard progressive case.
For instance, an initiator that must handle only a single progressive frame-buffer in any orientation of:
requires a line buffer of at least 15,360 bytes because:
and a line buffer of at least 30,720 bytes when using a simple ping-pong buffer scheme.