From 030929dd0663c5e97a02132ce037580167c28cca Mon Sep 17 00:00:00 2001 From: Ulf Zibis Date: 12.07.2019, 23:24:24 avutil/statistics: New statistic functions for mean and variance diff --git a/Changelog b/Changelog index c22d16c..1a8b249 100644 --- a/Changelog +++ b/Changelog @@ -36,6 +36,7 @@ - derain filter - deesser filter - mov muxer writes tracks with unspecified language instead of English by default +- libavutil statistics version 4.1: diff --git a/libavutil/Makefile b/libavutil/Makefile index 8a7a44e..356d80f 100644 --- a/libavutil/Makefile +++ b/libavutil/Makefile @@ -69,6 +69,7 @@ sha.h \ sha512.h \ spherical.h \ + statistics.h \ stereo3d.h \ threadmessage.h \ time.h \ @@ -150,6 +151,7 @@ sha512.o \ slicethread.o \ spherical.o \ + statistics.o \ stereo3d.o \ threadmessage.o \ time.o \ diff --git a/libavutil/statistics.c b/libavutil/statistics.c new file mode 100644 index 0000000..8a90d8a --- /dev/null +++ b/libavutil/statistics.c @@ -0,0 +1,71 @@ +/* + * statistic functions + * Copyright (c) 2019 Ulf Zibis + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * statistic functions, mostly useful for debugging/logging purposes + * @author Michael Ulf Zibis + */ + +#include "common.h" +#include "statistics.h" + +float av_weighted_arith_mean(int16_t x_0, int16_t *weights, uint16_t span) +{ + float weights_sum = 0, weighted_sum = 0; + for (int16_t i = 0, x = x_0; i < span; i++, x++) { + weighted_sum += x * weights[i]; + weights_sum += weights[i]; + } + return weighted_sum / weights_sum; +} + +float av_weighted_quadr_mean(int16_t x_0, int16_t *weights, uint16_t span, uint8_t signd) +{ + float weights_sum = 0, weighted_sum = 0; + for (int16_t i = 0, x = x_0; i < span; i++, x++) { + weighted_sum += weights[i] * pow(x, 2) * (signd && x < 0 ? -1 : 1); + weights_sum += weights[i]; + } + weighted_sum /= weights_sum; + return sqrt(fabs(weighted_sum)) * (weighted_sum < 0 ? -1 : 1); +} + +float av_weighted_cubic_mean(int16_t x_0, int16_t *weights, uint16_t span) +{ + float weights_sum = 0, weighted_sum = 0; + for (int16_t i = 0, x = x_0; i < span; i++, x++) { + weighted_sum += weights[i] * pow(x, 3); + weights_sum += weights[i]; + } + weighted_sum /= weights_sum; + return pow(fabs(weighted_sum), 1 / 3.0) * (weighted_sum < 0 ? -1 : 1); +} + +float av_weighted_variance(int16_t x_0, int16_t *weights, uint16_t span, float mean) +{ + float weights_sum = 0, weighted_sum = 0; + for (int16_t i = 0, x = x_0; i < span; i++, x++) { + weighted_sum += pow(x, 2) * weights[i]; + weights_sum += weights[i]; + } + return sqrt(weighted_sum / weights_sum - pow(mean, 2)); +} diff --git a/libavutil/statistics.h b/libavutil/statistics.h new file mode 100644 index 0000000..50c29d9 --- /dev/null +++ b/libavutil/statistics.h @@ -0,0 +1,77 @@ +/* + * statistic functions + * Copyright (c) 2019 Ulf Zibis + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * statistic functions, mostly useful for debugging/logging purposes + * @author Michael Ulf Zibis + */ + +#ifndef AVUTIL_STATISTICS_H +#define AVUTIL_STATISTICS_H + +#if defined(__cplusplus) && !defined(__STDC_FORMAT_MACROS) && !defined(PRId64) +#error missing -D__STDC_FORMAT_MACROS / #define __STDC_FORMAT_MACROS +#endif + +/** + * Calculate the weighted arithmetical mean of a given value span. + * + * @param x_0 the first value of the span + * @param weights the array with the corresponding weights, must at least contain span values + * @param span the number of values from x_0 on + * @return the weighted arithmetical mean + */ +float av_weighted_arith_mean(int16_t x_0, int16_t *weights, uint16_t span); + +/** + * Calculate the weighted quadratical mean of a given value span. + * + * @param x_0 the first value of the span + * @param weights the array with the corresponding weights, must at least contain span values + * @param span the number of values from x_0 on + * @param signd if true, respect signed values and return signed result + * @return the weighted quadratical mean + */ +float av_weighted_quadr_mean(int16_t x_0, int16_t *weights, uint16_t span, uint8_t signd); + +/** + * Calculate the weighted cubic mean of a given value span. + * + * @param x_0 the first value of the span + * @param weights the array with the corresponding weights, must at least contain span values + * @param span the number of values from x_0 on + * @return the weighted cubic mean + */ +float av_weighted_cubic_mean(int16_t x_0, int16_t *weights, uint16_t span); + +/** + * Calculate the weighted variance of a given value span. + * + * @param x_0 the first value of the span + * @param weights the array with the corresponding weights, must at least contain span values + * @param span the number of values from x_0 on + * @param mean the to be precalculated mean of the given value span + * @return the weighted variance + */ +float av_weighted_variance(int16_t x_0, int16_t *weights, uint16_t span, float mean); + +#endif /* AVUTIL_STATISTICS_H */