Per-camera capture interval; ambient recorder; fix 4-seasons one-frame bug

Per-camera capture interval:
  CAPTURE_INTERVAL_<cam> in sky-cam.conf overrides the global value for
  a specific camera.  capture.sh and 4-seasons.sh both respect it.
  Example: south at 30s saves storage; north at 5s gives smoother motion.

4-seasons.sh one-frame bug fix:
  Same root cause as the sunrise scripts — concat list had no 'duration'
  entries, collapsing all JPEG frames to timestamp 0.  Fixed by writing
  'duration INTERVAL' per frame.  Added fps=25 to the speed-adjust step
  so the VFR source resamples to a standard frame rate.

ambient-record.sh (new):
  Continuous AAC recorder for natural sounds (birds, rain, wind).
  Saves AMBIENT_CHUNK_SECS chunks to AMBIENT_DIR/<cam>/YYYY-MM-DD/HH-MM-SS.m4a.
  Reconnects automatically on stream failure.  Rolling retention via
  AMBIENT_RETENTION_DAYS.  Enabled by setting AMBIENT_ENABLED=true and
  listing cameras in AMBIENT_CAMS in sky-cam.conf, then re-running install.sh.

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

4-seasons.sh

@@ -72,6 +72,10 @@ if [ "$total_images" -lt 1 ]; then
 fi
 echo "Images found: $total_images"
 
+# ── Per-camera capture interval ───────────────────────────────────────────────
+interval_var="CAPTURE_INTERVAL_${CAM_NAME}"
+INTERVAL="${!interval_var:-${CAPTURE_INTERVAL:-10}}"
+
 # ── Prepare output directory ──────────────────────────────────────────────────
 output_dir="$MOVIES_DIR/$CAM_NAME/$ASTRO_YEAR/$SEASON/Mvt$MVT_NUM"
 mkdir -p "$output_dir"
@@ -82,12 +86,14 @@ temp_video="$output_dir/${yesterday}_Mvt${MVT_NUM}-temp.mp4"
 cleanup() { rm -f "$temp_file" "$temp_video" 2>/dev/null || true; }
 trap cleanup EXIT
 
-find "$image_dir" -type f -name "*.jpg" | sort | while read -r img; do
+mapfile -t images < <(find "$image_dir" -type f -name "*.jpg" | sort)
-    echo "file '$img'"
+for img in "${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 at default frame rate ─────────────────────────────
+# ── Step 1: Build raw video ───────────────────────────────────────────────────
-echo "Step 1/2: encoding raw video..."
+echo "Step 1/2: encoding raw video from ${#images[@]} frames..."
 ffmpeg -loglevel warning \
     -f concat -safe 0 -i "$temp_file" \
     -c:v libx264 -pix_fmt yuv420p -preset "$ENCODE_PRESET" -crf "$CRF_SEASONS_RAW" -vsync 2 -an \
@@ -103,7 +109,7 @@ echo "Step 2/2: speed factor $speed_factor..."
 final_file="$output_dir/${yesterday}_Mvt${MVT_NUM}-Day${DAY_OF_MVT}of${DAYS_IN_MVT}-final.mp4"
 if ! ffmpeg -loglevel warning \
     -i "$temp_video" \
-    -vf "setpts=PTS/$speed_factor" \
+    -vf "setpts=PTS/$speed_factor,fps=25" \
     -c:v libx264 -pix_fmt yuv420p -preset "$ENCODE_PRESET" -crf "$CRF_SEASONS_FINAL" \
     -t "$target_per_clip" -an \
     -y "$final_file"; then

ambient-record.sh

@@ -0,0 +1,79 @@
+#!/bin/bash
+# ambient-record.sh <cam-name> — continuous ambient audio recorder.
+#
+# Records RTSP audio in AMBIENT_CHUNK_SECS chunks, saves to:
+#   AMBIENT_DIR/<cam>/YYYY-MM-DD/HH-MM-SS.m4a
+#
+# Files are named by the recording start time so the collection is easy to
+# browse and pick from for white-noise / nature sound playback.
+#
+# Runs as a permanent systemd service (Type=simple) alongside capture.sh.
+# Reconnects automatically if the camera stream drops.
+# Applies rolling retention (AMBIENT_RETENTION_DAYS).
+#
+# Camera audio is typically 8 kHz mono (phone quality) — suitable for bird
+# song, rain, wind, and ambient nature sounds; check your camera's web
+# interface for a higher sample rate setting if available.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(dirname "$(realpath "$0")")"
+source "$SCRIPT_DIR/sky-cam.conf"
+source "$SCRIPT_DIR/.env" 2>/dev/null || true
+export TZ="$TIMEZONE"
+
+CAM="${1:-}"
+if [ -z "$CAM" ]; then
+    echo "Usage: $0 <camera-name>"
+    exit 1
+fi
+
+rtsp_var="CAM_RTSP_${CAM}"
+RTSP_URL="${!rtsp_var:-}"
+if [ -z "$RTSP_URL" ]; then
+    echo "ERROR: CAM_RTSP_${CAM} not set in .env"
+    exit 1
+fi
+
+CHUNK="${AMBIENT_CHUNK_SECS:-1800}"
+BITRATE="${AMBIENT_BITRATE:-96k}"
+RETAIN="${AMBIENT_RETENTION_DAYS:-30}"
+SAVE_DIR="${AMBIENT_DIR:-$BASE_DIR/ambient}"
+
+echo "Ambient recorder started: cam=$CAM  chunk=${CHUNK}s  bitrate=$BITRATE  retain=${RETAIN}d"
+echo "Saving to: $SAVE_DIR/$CAM/"
+
+while true; do
+    today=$(date +%Y-%m-%d)
+    dir="$SAVE_DIR/$CAM/$today"
+    mkdir -p "$dir"
+
+    timestamp=$(date +%H-%M-%S)
+    outfile="$dir/${timestamp}.m4a"
+
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] Recording → $outfile  (${CHUNK}s)"
+
+    ffmpeg -loglevel warning \
+        -rtsp_transport tcp \
+        -i "$RTSP_URL" \
+        -t "$CHUNK" \
+        -vn \
+        -c:a aac -b:a "$BITRATE" \
+        -y "$outfile" || true
+
+    if [ ! -s "$outfile" ]; then
+        echo "[$(date '+%Y-%m-%d %H:%M:%S')] [$CAM] recording failed or empty — retrying in 30s"
+        rm -f "$outfile"
+        sleep 30
+        continue
+    fi
+
+    actual=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$outfile" 2>/dev/null || echo "?")
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] Saved: $(basename "$outfile")  (${actual}s)"
+
+    # Rolling retention
+    if [ "${RETAIN}" -gt 0 ]; then
+        deleted=$(find "$SAVE_DIR/$CAM" -name "*.m4a" -mtime +"$RETAIN" -print -delete 2>/dev/null | wc -l)
+        [ "$deleted" -gt 0 ] && echo "Retention: deleted $deleted file(s) older than ${RETAIN}d"
+    fi
+done

capture.sh

@@ -31,7 +31,8 @@ if [ -z "$RTSP_URL" ]; then
     exit 1
 fi
 
-INTERVAL="${CAPTURE_INTERVAL:-10}"
+interval_var="CAPTURE_INTERVAL_${CAM}"
+INTERVAL="${!interval_var:-${CAPTURE_INTERVAL:-10}}"
 echo "Starting capture: cam=$CAM  interval=${INTERVAL}s"
 
 while true; do

install.sh

@@ -187,6 +187,38 @@ if [ "${AUDIO_ENABLED:-false}" = "true" ]; then
     timers+=("sky-cam-audio-capture")
 fi
 
+# ── Ambient audio recording services ─────────────────────────────────────────
+# One long-running service per camera in AMBIENT_CAMS.
+# Enabled alongside the capture services so install.sh restarts them on update.
+if [ "${AMBIENT_ENABLED:-false}" = "true" ]; then
+    for cam in "${AMBIENT_CAMS[@]}"; do
+        rtsp_var="CAM_RTSP_${cam}"
+        if [ -n "${!rtsp_var:-}" ]; then
+            cat > "$UNIT_DIR/sky-cam-ambient-${cam}.service" <<EOF
+[Unit]
+Description=Sky-Cam — ${cam}: ambient audio recorder
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=$SCRIPT_DIR/ambient-record.sh ${cam}
+Restart=on-failure
+RestartSec=30
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=default.target
+EOF
+            echo "  wrote sky-cam-ambient-${cam}.service"
+            capture_services+=("sky-cam-ambient-${cam}")
+        else
+            echo "  WARNING: CAM_RTSP_${cam} not set — skipping ambient service for ${cam}"
+        fi
+    done
+fi
+
 # ── Per-camera Four Seasons jobs ─────────────────────────────────────────────
 # Reads CAMERAS and SCHEDULE_SEASONS_<cam> from sky-cam.conf.
 # Script receives the camera name as $1 so it knows which camera to process.

sky-cam.conf

@@ -287,8 +287,16 @@ MONTAGE_MUSIC_LOOPS_Spring_2=2
 # CAPTURE_STALE_SECS should always be at least 2× CAPTURE_INTERVAL.
 CAPTURE_INTERVAL=10
 
+# Per-camera overrides — uncomment and set to override the global value above.
+# Useful when cameras serve different purposes (e.g. south records ambient audio
+# so fewer frames is fine; north faces a busy scene and benefits from 5s).
+#CAPTURE_INTERVAL_east=10
+#CAPTURE_INTERVAL_north=10
+#CAPTURE_INTERVAL_south=30
+
 # Seconds without a new frame before the watchdog sends a stall notification.
 # A recovery notification fires automatically when capture resumes.
+# Must always be at least 2× the effective CAPTURE_INTERVAL for that camera.
 CAPTURE_STALE_SECS=30
 
 # ── Sunrise audio capture ──────────────────────────────────────────────────────
@@ -302,6 +310,19 @@ CAPTURE_AUDIO_BITRATE=96k     # bitrate for the sunrise audio recording
 # Audio is recorded for exactly SUNRISE_TARGET_SECS, centred on actual sunrise:
 # floor(TARGET/2) seconds before, ceil(TARGET/2) after (odd second → post-sunrise).
 
+# ── Ambient audio library ──────────────────────────────────────────────────────
+# Continuously records natural sounds (birds, rain, wind) from AMBIENT_CAMS to
+# build a reusable audio library.  Runs as a permanent systemd service alongside
+# capture.sh.  Camera audio is 8 kHz mono (phone quality) — enough for nature
+# sounds and white-noise style playback.
+#
+AMBIENT_ENABLED=false
+AMBIENT_CAMS=(south)                    # cameras to record from
+AMBIENT_DIR="${BASE_DIR}/ambient"       # root storage directory
+AMBIENT_CHUNK_SECS=1800                 # seconds per file (default 30 min)
+AMBIENT_BITRATE=96k                     # AAC bitrate; 64–96k is plenty at 8 kHz
+AMBIENT_RETENTION_DAYS=30              # delete files older than this; 0 = keep forever
+
 # ── Mattermost — daily sunrise upload ─────────────────────────────────────────
 # mattermost_url, access_token, channel_id go in .env (see bottom of this file).