SPRUIL1D May 2019 – December 2024 DRA829J , DRA829J-Q1 , DRA829V , DRA829V-Q1 , TDA4VM , TDA4VM-Q1
This module down-samples the chroma components from 444-420 format; effectively reducing the chroma resolution to 50% in both the horizontal and vertical direction.
The downsampling is performed using a 3 Tap fitering [1 2 1] followed by decimation. The conversion logic generates chroma in co-sited/co-located format in both the horizontal and vertical direction.
Figure 6-96 shows the block diagram of the format conversion module. The Chorma output can be optionally downshifted from 12 bits to 8 bits using the LUT/SFT module. Only one copy of the Horizontal averaging filter is required since there is a decimation step following the filtering. Only even locations of both Cb/Cr are retained while the odd locations are decimated, however from design perspective the Hz Averager module works on Cb on even cycles and Cr on odd cycles.
Figure 6-96 444 to 420 ModuleAdditionally another mode of operation is to support planar YUV422 mode. In this case the chroma is only downsampled in the horizontal direction and the vertical averaging/downsampling is disabled.
The mode is referred to pseudo 422 since actual 422 mode requires the data to be interleaved between the Y and the chroma channels. In this case the interleaving of Y & C is handled by LSE whereas the Flexible CC module will only generate Y & Cb/Cr (interleaved) planes separately.