Pi-Eye

A simple web page to take pictures, create time lapse and record videos with your raspberry pi.

Summary

Pi-Eye is a web interface to trigger raspistill and raspivid on your Raspberry Pi. Behind the scene it is using NodeJS (ExpressJS to be more specific.)

Installation

Prerequisites

raspistill and raspivid

I assume your Raspberry is already able to take pictures and record videos using raspistill and raspivid. If you're not sure, have a look at the official documentation:

• Enable the camera.
• Take pictures.
• Record videos.

NodeJS (and npm)

I also assume you already have NodeJS and npm installed on your Pi. If not, have a look at this post on Stackoverflow.

As an example, for the Pi Zero W you need NodeJS for ARM 6:

wget https://nodejs.org/dist/latest-v10.x/node-v10.16.3-linux-armv6l.tar.gz
tar -xvf node-v10.16.3-linux-armv6l.tar.gz
sudo cp -r node-v10.16.3-linux-armv6l/* /usr/local/

MP4Box

Last assumption, to create an MP4 video from the raw H264 format raspivid is creating, you need MP4Box to be installed. This binary is part of the gpac package. sudo apt install gpac will do the trick. Be warned: it is a big package! 480 MB!

Download the NodeJS modules

The next step is to download the NodeJS dependencies by running the following command in the project folder:

npm install

Start the the server

The last step is to start the back-end server that will listen to your request and talk to the Pi and take some pictures and videos. To do that you have to run the following command:

npm start

Web Interface

The web interface is accessible on the port 3000. Find the IP address of your Pi (for instance using ifconfig) and use this address to open a browser.

For instance my IP address is 192.168.1.174. I can then point a browser to http://192.168.1.174:3000/ and I will see the web interface.

API

The web interface is using the API to do its job. If needed the interface can be skipped and the API can be contacted directly. For instance you can reuse the API and write your own interface to interact with it.

There are three routes so far:

Take a picture

To take a picture you need to call the /pic route and provide the correct name parameter.

GET /pic/:name

If the process is successfull, this will create a name.jpg picture in the public folder and return a JSON object:

{"status":"OK", "type": "image", "path": "/content/name.jpg"}

Create a timelapse

You can create a series of images using the /timelapse route. You need to provide a name prefix, a duration (in seconds) and an interval (in seconds).

GET /timelapse/:name/:duration/:interval

Here is a bit more details:

• name prefix: your images will start with this prefix and have a number from 000000 to 999999. For instance picture0001.jpg.
• duration: how many seconds the camera will stay active.
• interval: how many seconds between capturing two images.

For instance to take a picture every 10 seconds for one hour (3600 seconds) and name the file pic000***.jpg you will have to call:

GET /timelapse/pic/3600/10

For more info about timelapse with the raspberry pi you can read this page.

Record a video

A video recording can be triggered using the route:

GET /video/:name/:time_sec

• :name is obviously the name of the video with no extension.
• :time_sec is the duration in seconds of the video.

Behind the scene the application is calling the program raspivid. By default the camera is recording using the format (encoding?) h264. As soon as raspivid is finished the application starts a conversion to mp4 using MP4Box.

For instance to record a one minute video named myVid01.mp4 use the following:

GET /video/myVid01/60

As a video recording can be long the application is not waiting for the video to be recorded and sends the following response:

{"status":"pending","type":"video","path":"/content/myVid01.mp4"}

At the moment there is no way to retrieve an error message using the API if something went wrong. But it is possible to turn on the debug messages and see on the application logs if an error has been raised.

For info about the size of a video file: I made a one minute video and it was 126 927 324 bytes

Questions

• Q: What is the default format of the video?

• A: It is 1920 x 1080 pixels at 25 frames per second.

• Q: How big is a video?

• A: A one minute video was around 127 MB.

• Q: What is the default format of a picture?

• A: It is a JPG file at 2592 x 1944 pixels.

• Q: How big is a picture?

• A: With the default option used in the application a picture is around 2.5 MB

• Q: Why yet another module about the pi camera?

• A: I reviewed the existing ones and they were not exactly doing what I wanted. So, I decided to re-invent the wheel.

• Q: When are you going to make a nice web interface to the application?

• A: UPDATE! There is one now! OK, it is not the prettiest one... but it works! isn't it?...