lavfi/ebur128: print peak metering in dBFS

Signed-off-by: Jean First <jeanfirst@gmail.com>

doc/filters.texi

@@ -9334,13 +9334,14 @@ Disable any peak mode (default).
 @item sample
 Enable sample-peak mode.
 
-Simple peak mode looking for the higher sample value.
+Simple peak mode looking for the higher sample value. It logs a message
+for sample-peak (identified by @code{SPK}).
 @item true
 Enable true-peak mode.
 
 If enabled, the peak lookup is done on an over-sampled version of the input
-stream for better peak accuracy. This mode requires a build with
-@code{libswresample}.
+stream for better peak accuracy. It logs a message for true-peak.
+(identified by @code{TPK}). This mode requires a build with @code{libswresample}.
 @end table
 
 @end table

libavfilter/f_ebur128.c

@@ -23,7 +23,6 @@
  * EBU R.128 implementation
  * @see http://tech.ebu.ch/loudness
  * @see https://www.youtube.com/watch?v=iuEtQqC-Sqo "EBU R128 Introduction - Florian Camerer"
- * @todo True Peak
  * @todo implement start/stop/reset through filter command injection
  * @todo support other frequencies to avoid resampling
  */
@@ -443,6 +442,7 @@ static int config_audio_output(AVFilterLink *outlink)
 
 #define ENERGY(loudness) (pow(10, ((loudness) + 0.691) / 10.))
 #define LOUDNESS(energy) (-0.691 + 10 * log10(energy))
+#define DBFS(energy) (20 * log10(energy))
 
 static struct hist_entry *get_histogram(void)
 {
@@ -793,10 +793,10 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
 
 #define PRINT_PEAKS(str, sp, ptype) do {                            \
     if (ebur128->peak_mode & PEAK_MODE_ ## ptype ## _PEAKS) {       \
-        av_log(ctx, ebur128->loglevel, " [" str ":");           \
+        av_log(ctx, ebur128->loglevel, "  " str ":");               \
         for (ch = 0; ch < nb_channels; ch++)                        \
-            av_log(ctx, ebur128->loglevel, " %.5f", sp[ch]);    \
-        av_log(ctx, ebur128->loglevel, "]");                    \
+            av_log(ctx, ebur128->loglevel, " %5.1f", DBFS(sp[ch])); \
+        av_log(ctx, ebur128->loglevel, " dBFS");                    \
     }                                                               \
 } while (0)
 
@@ -867,11 +867,28 @@ static av_cold void uninit(AVFilterContext *ctx)
            "    LRA:       %5.1f LU\n"
            "    Threshold: %5.1f LUFS\n"
            "    LRA low:   %5.1f LUFS\n"
-           "    LRA high:  %5.1f LUFS\n",
+           "    LRA high:  %5.1f LUFS",
            ebur128->integrated_loudness, ebur128->i400.rel_threshold,
            ebur128->loudness_range,      ebur128->i3000.rel_threshold,
            ebur128->lra_low, ebur128->lra_high);
 
+#define PRINT_PEAK_SUMMARY(str, sp, ptype) do {                  \
+    int ch;                                                      \
+    double maxpeak;                                              \
+    maxpeak = 0.0;                                               \
+    if (ebur128->peak_mode & PEAK_MODE_ ## ptype ## _PEAKS) {    \
+        for (ch = 0; ch < ebur128->nb_channels; ch++)            \
+            maxpeak = FFMAX(maxpeak, sp[ch]);                    \
+        av_log(ctx, AV_LOG_INFO, "\n\n  " str " peak:\n"         \
+               "    Peak:      %5.1f dBFS",                      \
+               DBFS(maxpeak));                                   \
+    }                                                            \
+} while (0)
+
+    PRINT_PEAK_SUMMARY("Sample", ebur128->sample_peaks, SAMPLES);
+    PRINT_PEAK_SUMMARY("True",   ebur128->true_peaks,   TRUE);
+    av_log(ctx, AV_LOG_INFO, "\n");
+
     av_freep(&ebur128->y_line_ref);
     av_freep(&ebur128->ch_weighting);
     av_freep(&ebur128->true_peaks);