Picam
Picam is an Elixir library that provides a simple API for streaming MJPEG video and capturing JPEG stills using the camera module on Raspberry Pi devices running Linux.
Features currently supported by the API:
- Set sharpness, contrast, brightness, saturation, ISO, and shutter speed values
- Set the exposure, sensor, metering, and white balance modes
- Set image and color effects
- Rotate and flip the image vertically and horizontally
- Set the exposure compensation (EV) level
- Change the image size
- Adjust JPEG fidelity through quality level, restart intervals, and region of interest
- Enable or disable video stabilization
- Adjust the video framerate
- Display text annotations on the image frame(s)
For specifics on the above features, please consult the Hex docs.
Requirements
| Requirement | Notes | |
|---|---|---|
| Host Device | Raspberry Pi 1, 2, 3, Zero, Zero W | Zero and Zero W require a special ribbon cable |
| Operating System | Linux | Works out of the box with Raspian and Nerves builds |
| Camera Module | V1, V2 | Regular, NoIR |
| C Libraries | Broadcom VideoCore | Located in /opt/vc by default. Override with VIDEOCORE_DIR |
Installation
The package can be installed by adding picam to your list of dependencies in mix.exs:
def deps do
[{:picam, "~> 0.1.0"}]
end
Usage
Picam uses a port application named raspijpgs that interfaces with the underlying Multi-Media Abstraction Layer (MMAL) API in VideoCore. The port is started by the Picam.Camera process.
For example, to write a JPEG still using the :sketch image effect to /tmp/frame.jpg:
iex(1)> Picam.Camera.start_link
{:ok, #PID<0.160.0>}
iex(2)> Picam.set_img_effect(:sketch)
:ok
iex(3)> Picam.set_size(640, 0) # 0 automatically calculates height
:ok
iex(4)> File.write!(Path.join(System.tmp_dir!, "frame.jpg"), Picam.next_frame)
:ok
iex(5)> Picam.set_img_effect(:none) # Disable the effect
:ok
More than likely you'll want to put the Picam.Camera process in your supervision tree rather than starting it manually:
children = [
worker(Picam.Camera, []),
# ...
]
Examples
The examples directory is where you can find other useful demos of Picam in action. More examples will be added over time.
| Directory | Demo |
|---|---|
| picam_http | Streaming MJPEG video using plug |
Limitations
- Currently only one camera is supported. If you intend to use more than one camera through an add-on compute module, please submit an issue.
Copyright and License
Copyright (c) 2013-2017, Broadcom Europe Ltd, Silvan Melchior, James Hughes, Frank Hunleth, Jeff Smith
Picam source code is licensed under the BSD 3-Clause License.