Webcam over websocket in Python, using OpenCV and Tornado.
The code runs a recorder process that continuously reads images from the webcam. Upon every capture it updates the mapper, a tiny local storage server which keeps the latest captured image in memory. The mapper is accessible via plain socket interface.
Separately, a server process (running Tornado) handles websocket messages. Upon receiving a request message (sent from client web browser) it connects to the mapper, retrieves latest image and sends it to the client over websocket connection.
The client web page is dead simple:
It sends an initial request on a WebSocket.
When image data comes in, it assigns it to src attribute of the
<img> tag, then simply sends the next request. That's it!
The code uses Python and third-party modules installed in a
virtualenv with pip. But since OpenCV is not part
of the Python Package Index, you're gonna need to install
it system-wide. (Later below, make will manually pull the library
into the virtual environment):
yum install opencv-python
Now go ahead and grab the source code repo:
git clone https://github.com/vmlaker/hello-websocket cd hello-websocket
Build the virtual environment with all needed modules:
make
There are three separate programs that need to be running:
- mapper - a lightweight server that keeps the current captured image in memory and serves it to multiple local clients.
- recorder - webcam capture process that feeds the mapper.
- server - the Tornado server which reads current image from the mapper and serves to requesting WebSocket clients.
First run the mapper:
make mapper
Now (in a different shell) run the recorder:
make recorder
Finally (in a third shell) run the server:
make server
Go to http://localhost:9000 to view the webcam.
If your O/S has
systemd
(e.g. Fedora), you have the option of installing
mapper, recorder and server as systemd services.
Begin by customizing settings in file systemd/hello.conf.
Then, from the project root directory, generate your service files:
python systemd/create.py
Install your newly-created services into your systemd location:
sudo cp `pwd`/systemd/*.service /usr/lib/systemd/system/
You can now start all three services by starting the server (mapper and recorder are dependencies, and will start automatically):
sudo systemctl start hws-server
To shut down all three services, just stop the mapper (recorder and server depend on mapper, and will stop automatically):
sudo systemctl stop hws-mapper