HISTOGRAM_MAX     332 libavfilter/af_astats.c     index = av_clip(FFABS(nd) * HISTOGRAM_MAX, 0, HISTOGRAM_MAX);
HISTOGRAM_MAX     336 libavfilter/af_astats.c         p->histogram[av_clip(FFABS(drop) * HISTOGRAM_MAX, 0, HISTOGRAM_MAX)]--;
HISTOGRAM_MAX     346 libavfilter/af_astats.c                 noise_floor = i / (double)HISTOGRAM_MAX;