diff --git a/src-lib/testdata/poc.sh b/src-lib/testdata/poc.sh
index 3072d3f..5e4d091 100644
--- a/src-lib/testdata/poc.sh
+++ b/src-lib/testdata/poc.sh
@@ -1,15 +1,24 @@
 #! /bin/bash
 
 py="$(cat <<EOF
-from sys import stdin; lines = [i.strip() for i in stdin.readlines()];
-def keyword(line):
-  return "keep" if "keep" in line else "drop"
-somelines = lines[:1]
-for i in range(1, len(lines)):
-  if keyword(somelines[-1]) != keyword(lines[i]):
-    somelines.append(lines[i-1])
+from sys import stdin, stderr
+lines = [i.strip() for i in stdin.readlines()]
+
+def frame_duplicate_status(line):
+  return "keep" if "keep" in line else "drop", "Parsed_mpdecimate_0" in line
+somelines = []
+for i in range(len(lines)):
+  status, relevant = frame_duplicate_status(lines[i])
+  if not relevant:
+    continue
+  if not somelines:
     somelines.append(lines[i])
-somelines = [(keyword(i), i.split("pts_time:")[1].split()[0]) for i in somelines]
+  else:
+    prev_status, _ = frame_duplicate_status(somelines[-1])
+    if status != prev_status:
+      somelines.append(lines[i-1])
+      somelines.append(lines[i])
+somelines = [(frame_duplicate_status(i)[0], i.split("pts_time:")[1].split()[0]) for i in somelines]
 
 # just the keeps
 somelines = [i for i in somelines[2:] if i[0] == "keep"]
@@ -46,10 +55,13 @@ EOF
 d=$(mktemp -d)
 echo d=$d >&2
 for span in $(
-   ffmpeg -i $f -vf mpdecimate -loglevel debug -f null - 2>&1 \
-   | grep Parsed_mpdecimate_0 \
-   | grep -E ' (keep|drop) ' \
-   | python3 -c "$py"
+   (
+      ffmpeg -i $f -vf mpdecimate -af silencedetect=n=-50dB:d=1 -loglevel debug -f null -
+      #ffmpeg -i "$f" -af silencedetect=n=-50dB:d=1 -loglevel debug -f null -
+   ) 2>&1 \
+   | grep -E 'silencedetect|Parsed_mpdecimate_0|Duration: *[0-9]' \
+   | grep -E 'silencedetect| (keep|drop) |Duration: *[0-9]' \
+   | python3 -c "$py" >&2
 ); do
    n=$((n+1))
    ffmpeg -y -ss ${span%,*} -i "$f" -t ${span#*,} "$d/$(printf "%05d" $(ls "$d" | wc -l)).${f##*.}"
diff --git a/src-lib/testdata/stackoverflow.sh b/src-lib/testdata/stackoverflow.sh
index 96ba98e..3e6b9c1 100644
--- a/src-lib/testdata/stackoverflow.sh
+++ b/src-lib/testdata/stackoverflow.sh
@@ -37,3 +37,11 @@ echo 'ffmpeg -y -i "$f" -filter:v "select='gt(scene,0.50)',showinfo" -f null - 2
 # ffmpeg -i input.mp4 -vf mpdecimate,setpts=N/FRAME_RATE/TB out.mp4
 # ffmpeg -i "$f" -vf "split=2[full][crop];[crop]mpdecimate=hi=16:lo=16:frac=1:max=1000[crop];[crop][full]overlay" "$g"
 ffmpeg -y -i "$f" -vf "split=2[full][crop];[crop]mpdecimate,setpts=N/FRAME_RATE/TB[crop];[crop][full]overlay" "$g"
+
+# https://stackoverflow.com/questions/25697596/using-ffmpeg-with-silencedetect-to-remove-audio-silence
+#  [silencedetect @ 0000000004970f80] silence_start: -0.00154195
+#  [silencedetect @ 0000000004970f80] silence_end: 3.20435 | silence_duration: 3.2059
+#  ...
+#  [silencedetect @ 0000000004970f80] silence_start: 343.84
+
+ffmpeg -i "$f" -af silencedetect=n=-50dB:d=1 -f null - 2>&1 | grep silencedetect