Reduced Memory Mode
10-19
Display Mode 7 - Interlaced Luma/Interlaced Chroma with
Repositioning. Both the luma data and chroma data are treated as
interlaced. The chroma data is ltered using the bilinear chroma lter
to improve the chroma positioning. This display mode is suited for
either eld- or frame-structure pictures.
Display Mode 8 - Interlaced Luma/Interlaced Chroma 0.75
Letterbox Filtering. Both the luma and chroma data is treated as
interlaced and processed through the letterbox lter to achieve
decimation of four lines down to three. The main start and end rows
must be adjusted to account for this 0.75 decimation. The total
number of lines per eld should be adjusted according to the
following equation:
Display Mode 11 (0xB) - Interlaced Luma/Interlaced Chroma 0.5
Letterbox Filtering. Both the luma and chroma data is treated as
interlaced and processed through the letterbox lter to achieve
decimation of four lines down to two. The main start and end rows
must be adjusted to account for this 0.5 decimation. The total
number of lines per eld should be adjusted according to the
following equation:
10.7 Reduced Memory Mode
For applications where SDRAM space is limited, Reduced Memory Mode
(RMM) may be enabled to reduce the memory required for B-frame
reconstruction. RMM is intended for applications with PAL resolution
images, or when large OSD display areas limit the availability of SDRAM.
Since RMM overwrites the memory used for decoding the rst eld of the
B frame immediately after display, only a subset of the display modes
and features are available for use in RMM. The available display modes
include 4, 5, 6, 7, 8, and 10. However, since display modes 4 and 5
repeat the entire eld of chroma during the second eld time, only luma
data can utilize the benets of the reduced memory frame store. Care
must be taken to allot enough memory for the entire frame of chroma.
Main End Row - Main Start Row + 1 = (0.75*lines/field) - 2
Main End Row - Main Start Row + 1 = (0.5*lines/field) - 2