diff --git a/4-seasons.sh b/4-seasons.sh
index f308b29..344ada0 100755
--- a/4-seasons.sh
+++ b/4-seasons.sh
@@ -86,14 +86,26 @@ temp_video="$output_dir/${yesterday}_Mvt${MVT_NUM}-temp.mp4"
 cleanup() { rm -f "$temp_file" "$temp_video" 2>/dev/null || true; }
 trap cleanup EXIT
 
-mapfile -t images < <(find "$image_dir" -type f -name "*.jpg" | sort)
+mapfile -t all_images < <(find "$image_dir" -type f -name "*.jpg" | sort)
+images=()
+bad=0
+for img in "${all_images[@]}"; do
+    if [ -r "$img" ] && [ -s "$img" ]; then
+        images+=("$img")
+    else
+        echo "WARNING: skipping unreadable/empty frame: $img"
+        ((bad++)) || true
+    fi
+done
+[ "$bad" -gt 0 ] && echo "WARNING: skipped $bad bad frame(s) out of ${#all_images[@]} found"
+
 for img in "${images[@]}"; do
     printf "file '%s'\nduration %s\n" "$img" "$INTERVAL"
 done > "$temp_file"
 printf "file '%s'\n" "${images[-1]}" >> "$temp_file"
 
 # ── Step 1: Build raw video ───────────────────────────────────────────────────
-echo "Step 1/2: encoding raw video from ${#images[@]} frames..."
+echo "Step 1/2: encoding raw video from ${#images[@]} frames ($(( ${#images[@]} * INTERVAL / 3600 ))h coverage)..."
 ffmpeg -loglevel warning \
     -f concat -safe 0 -i "$temp_file" \
     -c:v libx264 -pix_fmt yuv420p -preset "$ENCODE_PRESET" -crf "$CRF_SEASONS_RAW" -vsync 2 -an \
@@ -101,6 +113,14 @@ ffmpeg -loglevel warning \
 
 raw_duration=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$temp_video")
 echo "Raw duration: $raw_duration s"
+# Warn if raw video covers less than 50% of expected image count (big gap or camera outage)
+expected_dur=$(echo "scale=0; ${#images[@]} * $INTERVAL" | bc)
+coverage_pct=$(echo "scale=0; $raw_duration * 100 / $expected_dur" | bc 2>/dev/null || echo "?")
+if [ "$coverage_pct" != "?" ] && [ "$coverage_pct" -lt 50 ]; then
+    echo "WARNING: raw video is ${coverage_pct}% of expected ${expected_dur}s — significant image gap detected"
+    "$SCRIPT_DIR/notify.sh" "WARNING: [$CAM_NAME] $SEASON Mvt$MVT_NUM Day$DAY_OF_MVT — only ${coverage_pct}% coverage ($yesterday)" \
+        "Raw video ${raw_duration}s of expected ${expected_dur}s — check camera logs for gaps" || true
+fi
 
 # ── Step 2: Speed-adjust to target clip duration ──────────────────────────────
 speed_factor=$(echo "scale=6; $raw_duration / $target_per_clip" | bc)