SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The Horizontal scaler is implemented using a 32-phase × 7-tap polyphase filter preceded by two sets of 1/2x decimators. The general configuration of the Horizontal scaler is performed as follows:
if (scale_factor>=1/2) {
mux=0; mod_scale_factor=scale factor;
} else if (scale_factor>=1/4) {
mux=1; mod_scale_factor=2*scale_factor;
} else {
mux=2; mod_scale_factor=4*scale_factor;
}
In auto mode (CFG_AUTO_HS == 1), scaler will operate as per above recommendation. In addition to this, for (CFG_AUTO_HS==1), polyphase filtering will be bypassed when (scale_factor == 1) or (scale_factor == ½) or (scale_factor == ¼). If CFG_AUTO_HS==0) is used, user must provide proper values for dcm_2x, dcm_4x, proper values for all inputs to polyphase filter in the registers as well as appropriate coefficient sets. There is no constraint on polyphase filtering in terms of scaling ratio. However, there are constraints on input and output image width for scaler. Frame dimensions are limited from 64x64 to 2047x2047.