INTERP            171 libavfilter/vf_fade.c             p[r_idx] = INTERP(r_idx, 0);
INTERP            172 libavfilter/vf_fade.c             p[g_idx] = INTERP(g_idx, 1);
INTERP            173 libavfilter/vf_fade.c             p[b_idx] = INTERP(b_idx, 2);
INTERP            175 libavfilter/vf_fade.c                 p[a_idx] = INTERP(a_idx, 3);