avfilter/af_astats: add RMS difference too

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -1614,6 +1614,7 @@ Max_level
 Min_difference
 Max_difference
 Mean_difference
+RMS_difference
 Peak_level
 RMS_peak
 RMS_trough
@@ -1629,6 +1630,7 @@ Max_level
 Min_difference
 Max_difference
 Mean_difference
+RMS_difference
 Peak_level
 RMS_level
 RMS_peak
@@ -1670,6 +1672,9 @@ Maximal difference between two consecutive samples.
 Mean difference between two consecutive samples.
 The average of each difference between two consecutive samples.
 
+@item RMS difference
+Root Mean Square difference between two consecutive samples.
+
 @item Peak level dB
 @item RMS level dB
 Standard peak and RMS level measured in dBFS.

libavfilter/af_astats.c

@@ -36,6 +36,7 @@ typedef struct ChannelStats {
     double min_runs, max_runs;
     double min_diff, max_diff;
     double diff1_sum;
+    double diff1_sum_x2;
     uint64_t mask, imask;
     uint64_t min_count, max_count;
     uint64_t nb_samples;
@@ -121,6 +122,7 @@ static void reset_stats(AudioStatsContext *s)
         p->min_runs = 0;
         p->max_runs = 0;
         p->diff1_sum = 0;
+        p->diff1_sum_x2 = 0;
         p->mask = 0;
         p->imask = 0xFFFFFFFFFFFFFFFF;
         p->min_count = 0;
@@ -197,6 +199,7 @@ static inline void update_stat(AudioStatsContext *s, ChannelStats *p, double d,
     p->min_diff = FFMIN(p->min_diff, fabs(d - p->last));
     p->max_diff = FFMAX(p->max_diff, fabs(d - p->last));
     p->diff1_sum += fabs(d - p->last);
+    p->diff1_sum_x2 += (d - p->last) * (d - p->last);
     p->last = d;
     p->mask |= i;
     p->imask &= i;
@@ -232,6 +235,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
            nmin = DBL_MAX, nmax = DBL_MIN,
            max_sigma_x = 0,
            diff1_sum = 0,
+           diff1_sum_x2 = 0,
            sigma_x = 0,
            sigma_x2 = 0,
            min_sigma_x2 = DBL_MAX,
@@ -251,7 +255,8 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
         nmax = FFMAX(nmax, p->nmax);
         min_diff = FFMIN(min_diff, p->min_diff);
         max_diff = FFMAX(max_diff, p->max_diff);
-        diff1_sum += p->diff1_sum,
+        diff1_sum += p->diff1_sum;
+        diff1_sum_x2 += p->diff1_sum_x2;
         min_sigma_x2 = FFMIN(min_sigma_x2, p->min_sigma_x2);
         max_sigma_x2 = FFMAX(max_sigma_x2, p->max_sigma_x2);
         sigma_x += p->sigma_x;
@@ -272,6 +277,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
         set_meta(metadata, c + 1, "Min_difference", "%f", p->min_diff);
         set_meta(metadata, c + 1, "Max_difference", "%f", p->max_diff);
         set_meta(metadata, c + 1, "Mean_difference", "%f", p->diff1_sum / (p->nb_samples - 1));
+        set_meta(metadata, c + 1, "RMS_difference", "%f", sqrt(p->diff1_sum_x2 / (p->nb_samples - 1)));
         set_meta(metadata, c + 1, "Peak_level", "%f", LINEAR_TO_DB(FFMAX(-p->nmin, p->nmax)));
         set_meta(metadata, c + 1, "RMS_level", "%f", LINEAR_TO_DB(sqrt(p->sigma_x2 / p->nb_samples)));
         set_meta(metadata, c + 1, "RMS_peak", "%f", LINEAR_TO_DB(sqrt(p->max_sigma_x2)));
@@ -290,6 +296,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
     set_meta(metadata, 0, "Overall.Min_difference", "%f", min_diff);
     set_meta(metadata, 0, "Overall.Max_difference", "%f", max_diff);
     set_meta(metadata, 0, "Overall.Mean_difference", "%f", diff1_sum / (nb_samples - s->nb_channels));
+    set_meta(metadata, 0, "Overall.RMS_difference", "%f", sqrt(diff1_sum_x2 / (nb_samples - s->nb_channels)));
     set_meta(metadata, 0, "Overall.Peak_level", "%f", LINEAR_TO_DB(FFMAX(-nmin, nmax)));
     set_meta(metadata, 0, "Overall.RMS_level", "%f", LINEAR_TO_DB(sqrt(sigma_x2 / nb_samples)));
     set_meta(metadata, 0, "Overall.RMS_peak", "%f", LINEAR_TO_DB(sqrt(max_sigma_x2)));
@@ -419,6 +426,7 @@ static void print_stats(AVFilterContext *ctx)
            min = DBL_MAX, max = DBL_MIN, min_diff = DBL_MAX, max_diff = 0,
            nmin = DBL_MAX, nmax = DBL_MIN,
            max_sigma_x = 0,
+           diff1_sum_x2 = 0,
            diff1_sum = 0,
            sigma_x = 0,
            sigma_x2 = 0,
@@ -439,7 +447,8 @@ static void print_stats(AVFilterContext *ctx)
         nmax = FFMAX(nmax, p->nmax);
         min_diff = FFMIN(min_diff, p->min_diff);
         max_diff = FFMAX(max_diff, p->max_diff);
-        diff1_sum += p->diff1_sum,
+        diff1_sum_x2 += p->diff1_sum_x2;
+        diff1_sum += p->diff1_sum;
         min_sigma_x2 = FFMIN(min_sigma_x2, p->min_sigma_x2);
         max_sigma_x2 = FFMAX(max_sigma_x2, p->max_sigma_x2);
         sigma_x += p->sigma_x;
@@ -461,6 +470,7 @@ static void print_stats(AVFilterContext *ctx)
         av_log(ctx, AV_LOG_INFO, "Min difference: %f\n", p->min_diff);
         av_log(ctx, AV_LOG_INFO, "Max difference: %f\n", p->max_diff);
         av_log(ctx, AV_LOG_INFO, "Mean difference: %f\n", p->diff1_sum / (p->nb_samples - 1));
+        av_log(ctx, AV_LOG_INFO, "RMS difference: %f\n", sqrt(p->diff1_sum_x2 / (p->nb_samples - 1)));
         av_log(ctx, AV_LOG_INFO, "Peak level dB: %f\n", LINEAR_TO_DB(FFMAX(-p->nmin, p->nmax)));
         av_log(ctx, AV_LOG_INFO, "RMS level dB: %f\n", LINEAR_TO_DB(sqrt(p->sigma_x2 / p->nb_samples)));
         av_log(ctx, AV_LOG_INFO, "RMS peak dB: %f\n", LINEAR_TO_DB(sqrt(p->max_sigma_x2)));
@@ -480,6 +490,7 @@ static void print_stats(AVFilterContext *ctx)
     av_log(ctx, AV_LOG_INFO, "Min difference: %f\n", min_diff);
     av_log(ctx, AV_LOG_INFO, "Max difference: %f\n", max_diff);
     av_log(ctx, AV_LOG_INFO, "Mean difference: %f\n", diff1_sum / (nb_samples - s->nb_channels));
+    av_log(ctx, AV_LOG_INFO, "RMS difference: %f\n", sqrt(diff1_sum_x2 / (nb_samples - s->nb_channels)));
     av_log(ctx, AV_LOG_INFO, "Peak level dB: %f\n", LINEAR_TO_DB(FFMAX(-nmin, nmax)));
     av_log(ctx, AV_LOG_INFO, "RMS level dB: %f\n", LINEAR_TO_DB(sqrt(sigma_x2 / nb_samples)));
     av_log(ctx, AV_LOG_INFO, "RMS peak dB: %f\n", LINEAR_TO_DB(sqrt(max_sigma_x2)));