stereo_transform 1123 libavfilter/af_surround.c         stereo_transform(&x, &y, s->angle);
stereo_transform 1159 libavfilter/af_surround.c         stereo_transform(&x, &y, s->angle);
stereo_transform 1194 libavfilter/af_surround.c         stereo_transform(&x, &y, s->angle);