Picamera2

Last reviewed Sep 13, 2026 · 805 words

Picamera2 is the right tool when you are writing the camera code, and the wrong tool when you just want a camera that records. It is Raspberry Pi's official Python library over libcamera, preinstalled on Raspberry Pi OS, BSD-2-Clause licensed, and it gives you a capture loop, an MJPEG or H.264 encoder and a file or network output in about 15 lines. What it does not give you is a web UI, a timeline, motion zones or a retention policy; those are an NVR's job, and a Pi with Picamera2 makes an excellent camera for Frigate or MotionEye rather than a replacement for them. Decide which side of that line you are on before you write anything.

Fifteen lines to a live stream

A minimal MJPEG server, roughly the mjpeg_server.py example in the repository, is enough to view the camera from any browser on the LAN:

from picamera2 import Picamera2
from picamera2.encoders import MJPEGEncoder
from picamera2.outputs import FileOutput

picam2 = Picamera2()
picam2.configure(picam2.create_video_configuration(main={"size": (1280, 720)}))
picam2.start_recording(MJPEGEncoder(), FileOutput(stream))

where stream is a small class that buffers each frame and an http.server handler that writes them out as multipart/x-mixed-replace. Swap MJPEGEncoder for H264Encoder and FileOutput for FfmpegOutput("-f rtsp rtsp://localhost:8554/cam") and the Pi publishes an RTSP feed that any NVR can consume, with a MediaMTX or go2rtc process holding the stream. That second pattern is the one I actually run: Picamera2 as the sensor driver, everything else off the Pi.

Pi 5 has no hardware encoder, and it matters

The Pi 4 and Zero 2 W encode H.264 in hardware, so a 1080p30 stream costs almost nothing. The Pi 5 dropped the hardware encoder, and Picamera2's H264Encoder on it runs in software on the CPU; 1080p30 is achievable but eats a core, and 4K from a Camera Module 3 or HQ camera is not realistic. MJPEG is cheap everywhere but 10 times the bandwidth. Plan the resolution and framerate around the board you have: 720p at 15 fps on a Zero 2 W with 256 MB free RAM, 1080p at 30 fps on a Pi 4, and CPU headroom on a Pi 5 if you also want to run detection on it.

Motion recording without an NVR

Picamera2 ships a CircularOutput that keeps the last few seconds of encoded video in RAM, so a script that detects motion can write a clip that starts before the trigger. The repository's capture_motion.py example compares consecutive frames from a low-resolution second stream with numpy and starts recording above a threshold; that is a 40-line DIY equivalent of the motion daemon. It is good for a doorbell-style single camera. It falls over the moment you want 3 cameras, object detection rather than pixel change, and a UI to review last night, which is where a proper NVR earns its RAM.

The libcamera break, and which camera to buy

Anything written for the old picamera library or raspistill does not work on current Raspberry Pi OS; the legacy stack was removed and Picamera2 with rpicam-apps replaced it. When copying examples, check the import line. On hardware, the Camera Module 3 (12 MP, autofocus, about 25 dollars at last check) is the default; the HQ Camera takes C-mount lenses for a fixed outdoor view; the Global Shutter camera is for fast motion. Third-party sensors need a device tree overlay and often a vendor libcamera fork, which is where "Raspberry Pi specific" in the cons becomes "one specific Pi image".

The bigger tools to compare against

For a no-code camera on the Pi itself, MotionEye wraps the motion daemon with a web UI and supports libcamera cameras through a streamer. For a multi-camera home system, Frigate on a separate x86 box or a Pi 5 with a Coral accelerator and each Pi camera as an RTSP source is the setup I recommend, and the video surveillance category lays out the field. Picamera2 sits underneath all of them on the camera side; it is never the thing you look at.

What I'd do

Write a 30-line Picamera2 script that publishes H.264 over RTSP through MediaMTX, run it as a systemd service on a Pi 4 or Zero 2 W with a Camera Module 3, and add that RTSP URL to Frigate. Keep the script dumb: no detection, no storage, no UI on the camera. Buy a Pi 5 for the NVR side rather than the camera side, because of the encoder. And if you only want one camera watching a doorway with clips in a folder, the CircularOutput motion example is a perfectly good evening project that needs nothing else installed.