find_best_pitch   958 libavfilter/af_arnndn.c     find_best_pitch(xcorr, y_lp4, len>>2, max_pitch>>2, best_pitch);
find_best_pitch   970 libavfilter/af_arnndn.c     find_best_pitch(xcorr, y, len>>1, max_pitch>>1, best_pitch);