diff --git a/roomcam-service/README.md b/roomcam-service/README.md
index bf319ce6..5df283a9 100644
--- a/roomcam-service/README.md
+++ b/roomcam-service/README.md
@@ -19,7 +19,7 @@ Lightweight systemd service that serves a JPEG snapshot from any MJPEG-capable w
    - `QUALITY=5` (ffmpeg MJPEG quality; lower is higher quality)
    - `PORT=8080`
    - `WORKDIR=/run/roomcam`
-   - `INPUT_FORMAT=mjpeg` (use `bayer_grbg8` for OV534/raw Bayer cams; auto-converts to JPEG)
+   - `INPUT_FORMAT=mjpeg` (use `bayer_grbg8` for OV534/raw Bayer cams; aliases `GRBG`/`grbg` are accepted)
 3) Point the server `roomCameras[].url` to `http://<host>:8080/snapshot.jpg`.
 
 Notes:
diff --git a/roomcam-service/room-cam-snapshot.sh b/roomcam-service/room-cam-snapshot.sh
index bfe056eb..056bcb51 100644
--- a/roomcam-service/room-cam-snapshot.sh
+++ b/roomcam-service/room-cam-snapshot.sh
@@ -12,6 +12,7 @@ INPUT_FORMAT="${INPUT_FORMAT:-mjpeg}"
 
 mkdir -p "${WORKDIR}"
 SNAPSHOT_PATH="${WORKDIR}/snapshot.jpg"
+rm -f "${SNAPSHOT_PATH}"
 
 cleanup() {
   [[ -n "${FFMPEG_PID:-}" ]] && kill "${FFMPEG_PID}" 2>/dev/null || true
@@ -27,7 +28,7 @@ if [[ "${INPUT_FORMAT}" == bayer_* ]]; then
   FFMPEG_FILTERS=(-pix_fmt yuv420p)
 fi
 
-/usr/bin/ffmpeg \
+/usr/bin/ffmpeg -y \
   -loglevel warning -nostats \
   "${FFMPEG_INPUT_ARGS[@]}" \
   "${FFMPEG_FILTERS[@]}" \
diff --git a/roomcam-service/room-cam.service b/roomcam-service/room-cam.service
index dde719d3..89c91630 100644
--- a/roomcam-service/room-cam.service
+++ b/roomcam-service/room-cam.service
@@ -10,6 +10,7 @@ Environment=RESOLUTION=640x480
 Environment=QUALITY=5
 Environment=PORT=8088
 Environment=WORKDIR=/run/roomcam
+Environment=INPUT_FORMAT=mjpeg
 WorkingDirectory=/home/daniel/gits/MultiRoombaRover/roomcam-service
 ExecStart=/usr/bin/env bash /home/daniel/gits/MultiRoombaRover/roomcam-service/room-cam-snapshot.sh
 Restart=always