VAR_S2R_MAIN_A    193 libavfilter/vf_scale.c          vars_w[VAR_S2R_MAIN_A]    || vars_h[VAR_S2R_MAIN_A]    ||
VAR_S2R_MAIN_A    442 libavfilter/vf_scale.c         scale->var_values[VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
VAR_S2R_MAIN_A    446 libavfilter/vf_scale.c             scale->var_values[VAR_S2R_MAIN_A] * scale->var_values[VAR_S2R_MAIN_SAR];