diff --git a/main.py b/main.py
index 65a9620..c2ade46 100644
--- a/main.py
+++ b/main.py
@@ -1,15 +1,21 @@
+import datetime
 from functools import partial
 import json
 from os import getuid
 from pathlib import Path
 from queue import Empty, Queue
 import subprocess
-from time import sleep
+from time import monotonic, sleep
 from typing import Literal
 import pyudev
 from gpiozero import LED, Button
 from threading import Thread, Event
 from dataclasses import asdict, dataclass
+import numpy as np
+from libcamera import controls
+from picamera2 import Picamera2
+from picamera2.encoders import H264Encoder
+from picamera2.outputs import CircularOutput
 
 red = LED(17)
 yellow = LED(27)
@@ -25,6 +31,7 @@ class DiskEvent:
 
 
 DiskState = Literal["disconnected", "pairing", "connecting", "connected"]
+CameraState = Literal["off", "armed", "recording"]
 
 
 @dataclass
@@ -35,10 +42,12 @@ class Config:
 @dataclass
 class AppState:
     stopEvent = Event()
+    cameraStopComplete = Event()
     diskEventQueue: Queue[DiskEvent] = Queue()
     diskState: DiskState = "disconnected"
     config = Config()
     failedUmount: bool = False
+    cameraState = "off"
 
 
 def saveConfig(config: Config, path: Path) -> None:
@@ -103,12 +112,14 @@ def diskPollWorker(state) -> None:
 
 def ledWorker(state: AppState) -> None:
     yellowCtr = 0
-    previousState: DiskState | None = None
+    blueCtr = 0
+    previousDiskState: DiskState | None = None
+    previousCameraState: CameraState | None = None
 
     while not state.stopEvent.is_set():
-        if state.diskState != previousState:
+        if state.diskState != previousDiskState:
             yellowCtr = 0
-            previousState = state.diskState
+            previousDiskState = state.diskState
 
         if state.diskState == "disconnected":
             yellow.off()
@@ -130,6 +141,20 @@ def ledWorker(state: AppState) -> None:
 
         yellowCtr += 1
 
+        if state.cameraState != previousCameraState:
+            blueCtr = 0
+            previousCameraState = state.cameraState
+
+        if state.cameraState == "off":
+            blue.off()
+        elif state.cameraState == "armed":
+            blue.on()
+        elif state.cameraState == "recording":
+            if blueCtr % 4 < 2:
+                blue.on()
+            else:
+                blue.off()
+
         state.stopEvent.wait(0.25)
 
 
@@ -152,10 +177,7 @@ def mountDisk(state: AppState) -> None:
     state.diskState = "connecting"
     node = findDiskNode(state.config.diskSerial)
     try:
-        subprocess.run(
-            ["mkdir", "-p", f"/mnt/{state.config.diskSerial}"],
-            check=True,
-        )
+        Path(f"/mnt/{state.config.diskSerial}").mkdir(parents=True, exist_ok=True)
         sleep(1)
         subprocess.run(
             [
@@ -205,6 +227,170 @@ def unmountDisk(state: AppState) -> None:
         state.failedUmount = False
 
 
+def cameraWorker(state: AppState) -> None:
+    VIDEO_SIZE = (1280, 720)
+    ANALYSIS_SIZE = (320, 240)
+
+    FRAME_RATE = 15
+    BITRATE = 2_000_000
+
+    QUIET_SECONDS = 10.0
+
+    PRE_RECORD_SECONDS = 2.0
+
+    WARMUP_SECONDS = 3.0
+
+    PIXEL_CHANGE_THRESHOLD = 25
+
+    MOTION_AREA_THRESHOLD = 0.015
+
+    ANALYSIS_SAMPLE_STEP = 2
+
+    OUTPUT_DIRECTORY = Path(f"/mnt/{state.config.diskSerial}/cctv")
+
+    camera = Picamera2()
+
+    configuration = camera.create_video_configuration(
+        main={
+            "size": VIDEO_SIZE,
+            "format": "YUV420",
+        },
+        lores={
+            "size": ANALYSIS_SIZE,
+            "format": "YUV420",
+        },
+        controls={
+            "FrameRate": FRAME_RATE,
+        },
+        buffer_count=6,
+    )
+
+    camera.configure(configuration)
+
+    camera.set_controls(
+        {
+            "AfMode": controls.AfModeEnum.Continuous,
+        }
+    )
+
+    encoder = H264Encoder(
+        bitrate=BITRATE,
+        repeat=True,
+        iperiod=FRAME_RATE,
+    )
+
+    prebuffer_frames = max(
+        1,
+        round(FRAME_RATE * PRE_RECORD_SECONDS),
+    )
+
+    circular_output = CircularOutput(
+        buffersize=prebuffer_frames,
+    )
+
+    encoder.output = circular_output
+
+    recording = False
+    recording_path: Path | None = None
+    recording_trigger_time = 0.0
+    last_motion_time = 0.0
+
+    camera_started = False
+    encoder_started = False
+
+    try:
+        camera.start()
+        camera_started = True
+
+        camera.start_encoder(encoder)
+        encoder_started = True
+
+        sleep(WARMUP_SECONDS)
+
+        analysis_width, analysis_height = ANALYSIS_SIZE
+
+        first_frame = camera.capture_array("lores")
+        previous_frame = first_frame[:analysis_height, :analysis_width]
+        previous_frame = previous_frame[
+            ::ANALYSIS_SAMPLE_STEP,
+            ::ANALYSIS_SAMPLE_STEP,
+        ].astype(np.int16)
+
+        while not state.stopEvent.is_set():
+            if state.diskState != "connected":
+                state.cameraState = "off"
+                state.stopEvent.wait(1)
+                continue
+            if state.cameraState == "off":
+                state.cameraState = "armed"
+            frame = camera.capture_array("lores")
+
+            # YUV420 starts with the full-resolution greyscale Y plane.
+            current_frame = frame[:analysis_height, :analysis_width]
+            current_frame = current_frame[
+                ::ANALYSIS_SAMPLE_STEP,
+                ::ANALYSIS_SAMPLE_STEP,
+            ].astype(np.int16)
+
+            difference = np.abs(current_frame - previous_frame)
+
+            changed_pixels = np.count_nonzero(difference >= PIXEL_CHANGE_THRESHOLD)
+
+            changed_fraction = changed_pixels / difference.size
+            motion_detected = changed_fraction >= MOTION_AREA_THRESHOLD
+
+            now = monotonic()
+
+            if motion_detected:
+                last_motion_time = now
+
+                if not recording:
+                    if not OUTPUT_DIRECTORY.exists():
+                        OUTPUT_DIRECTORY.mkdir(parents=True, exist_ok=True)
+
+                    filename_timestamp = datetime.now().strftime("%Y-%m-%d_%H-%M-%S")
+
+                    recording_path = OUTPUT_DIRECTORY / f"{filename_timestamp}.h264"
+
+                    # Start writing the circular pre-buffer and all subsequent
+                    # encoded H.264 packets directly to the file.
+                    circular_output.fileoutput = str(recording_path)
+                    circular_output.start()
+
+                    recording = True
+                    state.cameraState = "recording"
+                    recording_trigger_time = now
+
+            elif recording and now - last_motion_time >= QUIET_SECONDS:
+                circular_output.stop()
+                state.cameraState = "armed"
+                recording = False
+
+                elapsed = now - recording_trigger_time
+
+                recording_path = None
+
+            previous_frame = current_frame
+    finally:
+        if recording:
+            circular_output.stop()
+
+        if encoder_started:
+            try:
+                camera.stop_encoder()
+            except Exception:
+                pass
+
+        if camera_started:
+            try:
+                camera.stop()
+            except Exception:
+                pass
+
+        camera.close()
+        state.cameraStopComplete.set()
+
+
 def main() -> None:
     try:
         state = AppState()
@@ -257,6 +443,7 @@ def main() -> None:
 
     finally:
         state.stopEvent.set()
+        state.cameraStopComplete.wait()
         if state.diskState == "connected":
             unmountDisk(state)
             if state.failedUmount: