avfilter/af_astats: measure minimal and mean difference between two consecutive samples

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

doc/filters.texi

@@ -952,7 +952,9 @@ Available keys for each channel are:
 DC_offset
 Min_level
 Max_level
+Min_difference
 Max_difference
+Mean_difference
 Peak_level
 RMS_peak
 RMS_trough
@@ -965,7 +967,9 @@ and for Overall:
 DC_offset
 Min_level
 Max_level
+Min_difference
 Max_difference
+Mean_difference
 Peak_level
 RMS_level
 RMS_peak
@@ -997,9 +1001,16 @@ Minimal sample level.
 @item Max level
 Maximal sample level.
 
+@item Min difference
+Minimal difference between two consecutive samples.
+
 @item Max difference
 Maximal difference between two consecutive samples.
 
+@item Mean difference
+Mean difference between two consecutive samples.
+The average of each 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

@@ -33,7 +33,8 @@ typedef struct ChannelStats {
     double min, max;
     double min_run, max_run;
     double min_runs, max_runs;
-    double max_diff;
+    double min_diff, max_diff;
+    double diff1_sum;
     uint64_t mask;
     uint64_t min_count, max_count;
     uint64_t nb_samples;
@@ -104,7 +105,7 @@ static void reset_stats(AudioStatsContext *s)
 
         p->min = p->min_sigma_x2 = DBL_MAX;
         p->max = p->max_sigma_x2 = DBL_MIN;
-        p->max_diff = -1;
+        p->min_diff = p->max_diff = -1;
     }
 }
 
@@ -162,7 +163,9 @@ static inline void update_stat(AudioStatsContext *s, ChannelStats *p, double d)
     p->sigma_x += d;
     p->sigma_x2 += d * d;
     p->avg_sigma_x2 = p->avg_sigma_x2 * s->mult + (1.0 - s->mult) * d * d;
+    p->min_diff = FFMIN(p->min_diff == -1 ? DBL_MAX : p->min_diff, FFABS(d - (p->min_diff == -1 ? DBL_MAX : p->last)));
     p->max_diff = FFMAX(p->max_diff, FFABS(d - (p->max_diff == -1 ? d : p->last)));
+    p->diff1_sum += FFABS(d - p->last);
     p->last = d;
     p->mask |= llrint(d * (1LLU<<63));
 
@@ -193,8 +196,9 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
 {
     uint64_t mask = 0, min_count = 0, max_count = 0, nb_samples = 0;
     double min_runs = 0, max_runs = 0,
-           min = DBL_MAX, max = DBL_MIN, max_diff = 0,
+           min = DBL_MAX, max = DBL_MIN, min_diff = DBL_MAX, max_diff = 0,
            max_sigma_x = 0,
+           diff1_sum = 0,
            sigma_x = 0,
            sigma_x2 = 0,
            min_sigma_x2 = DBL_MAX,
@@ -209,7 +213,9 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
 
         min = FFMIN(min, p->min);
         max = FFMAX(max, p->max);
+        min_diff = FFMIN(min_diff, p->min_diff);
         max_diff = FFMAX(max_diff, p->max_diff);
+        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;
@@ -226,7 +232,9 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
         set_meta(metadata, c + 1, "DC_offset", "%f", p->sigma_x / p->nb_samples);
         set_meta(metadata, c + 1, "Min_level", "%f", p->min);
         set_meta(metadata, c + 1, "Max_level", "%f", p->max);
+        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, "Peak_level", "%f", LINEAR_TO_DB(FFMAX(-p->min, p->max)));
         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)));
@@ -240,7 +248,9 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
     set_meta(metadata, 0, "Overall.DC_offset", "%f", max_sigma_x / (nb_samples / s->nb_channels));
     set_meta(metadata, 0, "Overall.Min_level", "%f", min);
     set_meta(metadata, 0, "Overall.Max_level", "%f", max);
+    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.Peak_level", "%f", LINEAR_TO_DB(FFMAX(-min, max)));
     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)));
@@ -298,8 +308,9 @@ static void print_stats(AVFilterContext *ctx)
     AudioStatsContext *s = ctx->priv;
     uint64_t mask = 0, min_count = 0, max_count = 0, nb_samples = 0;
     double min_runs = 0, max_runs = 0,
-           min = DBL_MAX, max = DBL_MIN, max_diff = 0,
+           min = DBL_MAX, max = DBL_MIN, min_diff = DBL_MAX, max_diff = 0,
            max_sigma_x = 0,
+           diff1_sum = 0,
            sigma_x = 0,
            sigma_x2 = 0,
            min_sigma_x2 = DBL_MAX,
@@ -314,7 +325,9 @@ static void print_stats(AVFilterContext *ctx)
 
         min = FFMIN(min, p->min);
         max = FFMAX(max, p->max);
+        min_diff = FFMIN(min_diff, p->min_diff);
         max_diff = FFMAX(max_diff, p->max_diff);
+        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;
@@ -332,7 +345,9 @@ static void print_stats(AVFilterContext *ctx)
         av_log(ctx, AV_LOG_INFO, "DC offset: %f\n", p->sigma_x / p->nb_samples);
         av_log(ctx, AV_LOG_INFO, "Min level: %f\n", p->min);
         av_log(ctx, AV_LOG_INFO, "Max level: %f\n", p->max);
+        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, "Peak level dB: %f\n", LINEAR_TO_DB(FFMAX(-p->min, p->max)));
         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)));
@@ -348,7 +363,9 @@ static void print_stats(AVFilterContext *ctx)
     av_log(ctx, AV_LOG_INFO, "DC offset: %f\n", max_sigma_x / (nb_samples / s->nb_channels));
     av_log(ctx, AV_LOG_INFO, "Min level: %f\n", min);
     av_log(ctx, AV_LOG_INFO, "Max level: %f\n", max);
+    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, "Peak level dB: %f\n", LINEAR_TO_DB(FFMAX(-min, max)));
     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)));