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 writes the image to a Redis key-value store.
Separately, a server process (running Tornado) handles websocket messages. Upon receiving a request message (sent from client web browser) it retrieves the latest image from the Redis database 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):
apt-get install python-opencv
Also install Redis server:
apt-get install redis-server
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 two separate programs that need to be running:
- recorder - webcam capture process that writes to Redis database.
- server - the Tornado server which reads current image from the Redis database and serves to requesting WebSocket clients.
First run the recorder:
make recorder
Now (in a different shell) run the server:
make server
Go to http://localhost:9000 to view the webcam.
If your O/S has
systemd
you have the option of installing
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 the two services by starting the server (recorder is a dependency, 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