Audio resilience: three-tier fallback for sunrise audio; add freesound download script

daily_sunrise_video.sh: priority chain is camera mic → library random MP3 →
overlay-only → sped video promotion.  If audio mixing fails a warning
notification fires and the script retries with overlay-only so a video is
always produced and uploaded.

download-sunrise-sounds.py: downloads CC-licensed ambient sounds from
freesound.org into 11 weather/season category folders (~275 files total at
25 per category), writing a manifest.json with attribution data.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

daily_sunrise_video.sh

@@ -140,27 +140,62 @@ DT="${DT}:x=w-tw-18:y=(h-th)/2"
 DT="${DT}:shadowcolor=black@0.55:shadowx=1:shadowy=1"
 
 # ── Step 3: Overlay + optional audio ─────────────────────────────────────────
-# With audio: DT must go into -filter_complex (can't mix -vf and -filter_complex)
-# Without audio: plain -vf is simpler and avoids any filter_complex overhead.
-# If overlay fails either way, the sped video is promoted so upload still fires.
+# Priority: (1) camera mic recording, (2) library fallback, (3) no audio.
+# If audio mixing fails, step 3 retries with overlay-only so the video is
+# always made.  If overlay itself fails, the sped video is promoted so upload
+# still fires.
 final_video="$output_dir/$current_date-daily-sunrise.mp4"
-audio_file="$image_dir/sunrise-audio.m4a"
+fade_out=$(echo "scale=1; $SUNRISE_TARGET_SECS - 0.5" | bc)
+
+# ── Pick audio source ─────────────────────────────────────────────────────────
+audio_src=""
+audio_offset="0"
+
+cam_audio="$image_dir/sunrise-audio.m4a"
+if [ "${AUDIO_ENABLED:-false}" = "true" ]; then
+    if [ -f "$cam_audio" ]; then
+        # Camera recording: offset centres the clip on actual sunrise
+        buffer_sec=$(( ${AUDIO_PRE_BUFFER_MIN:-2} * 60 ))
+        audio_offset=$(echo "scale=1; $SUNRISE_PRE_MIN * 60 + $buffer_sec - $SUNRISE_TARGET_SECS / 2" | bc)
+        audio_src="$cam_audio"
+        echo "Audio: camera recording  offset=${audio_offset}s"
+    else
+        # Library fallback: random file from sunrise-sounds/
+        library_dir="$SCRIPT_DIR/sunrise-sounds"
+        if [ -d "$library_dir" ]; then
+            random_file=$(find "$library_dir" -name "*.mp3" | shuf -n 1 2>/dev/null || true)
+            if [ -n "$random_file" ]; then
+                audio_src="$random_file"
+                echo "Audio: library fallback  $(basename "$audio_src")"
+            fi
+        fi
+    fi
+fi
+
+# ── Attempt overlay + audio (falls back to overlay-only if audio fails) ───────
+audio_mixed=false
 step3_ok=true
 
-if [ "${AUDIO_ENABLED:-false}" = "true" ] && [ -f "$audio_file" ]; then
-    buffer_sec=$(( ${AUDIO_PRE_BUFFER_MIN:-2} * 60 ))
-    audio_offset=$(echo "scale=1; $SUNRISE_PRE_MIN * 60 + $buffer_sec - $SUNRISE_TARGET_SECS / 2" | bc)
-    fade_out=$(echo "scale=1; $SUNRISE_TARGET_SECS - 0.5" | bc)
-    echo "Step 3/3: overlay + camera audio (offset ${audio_offset}s) → $final_video"
-    ffmpeg -loglevel warning \
+if [ -n "$audio_src" ]; then
+    echo "Step 3/3: overlay + audio → $final_video"
+    if ffmpeg -loglevel warning \
         -i "$sped_video" \
-        -ss "$audio_offset" -t "$SUNRISE_TARGET_SECS" -i "$audio_file" \
+        -ss "$audio_offset" -t "$SUNRISE_TARGET_SECS" -i "$audio_src" \
         -filter_complex "[0:v]${DT}[vout];[1:a]afade=t=in:st=0:d=0.5,afade=t=out:st=${fade_out}:d=0.5[aout]" \
         -map "[vout]" -map "[aout]" \
         -c:v libx264 -pix_fmt yuv420p -crf "$CRF_SUNRISE" \
         -c:a aac -b:a 128k \
-        -y "$final_video" || step3_ok=false
-else
+        -y "$final_video"; then
+        audio_mixed=true
+    else
+        echo "Audio mix failed — retrying with overlay only"
+        "$SCRIPT_DIR/notify.sh" "WARNING: sunrise audio mix failed $current_date" \
+            "Audio could not be mixed — falling back to overlay-only" || true
+        [ "$audio_src" = "$cam_audio" ] && rm -f "$cam_audio"
+    fi
+fi
+
+if ! $audio_mixed; then
     echo "Step 3/3: overlay (no audio) → $final_video"
     ffmpeg -loglevel warning \
         -i "$sped_video" \
@@ -173,7 +208,7 @@ if $step3_ok; then
     actual_dur=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$final_video")
     echo "Done: $final_video  (${actual_dur}s, sunrise at ${SR_TIME})"
     rm -f "$sped_video"
-    [ -f "$audio_file" ] && rm -f "$audio_file"
+    [ -f "$cam_audio" ] && rm -f "$cam_audio"
     "$SCRIPT_DIR/notify.sh" "Sunrise ready: $current_date" \
         "$(basename "$final_video") — ${actual_dur}s, sunrise at ${SR_TIME}" || true
 else