The SVL CabCam Project

As Silicon Valley Lines adapts to the current global pandemic, it has become clear we will not be meeting as a full club in person for some time. This has spurred our search for a solution to allow us to run operating sessions and have fun with trains as SVL is foremost a operating layout. We tried a few approaches but it quickly became apparent that we need to give remote operators a way to get immersed with running a train on the layout. We wanted to provide a view from the locomotive cab that is fast and responsive. Thus the SVL CabCam Project was born. In addition we provide layout overview cameras and/or views from key locations on the railroad.

This write-up is the result of a lot of trial and error, getting products fully running then realizing the end-to-end latency was so severe it wouldn’t be workable. It is intended as a general overview for hobbyists wishing to get a track-level view of their own layout, and provides technical instructions for replicating our approach.

A cab view camera is useful for more than remote operations during COVID. Local ops sessions can benefit from this as well.

Overview

We describe how to set up a small computer to stream cab view video from an HO locomotive. This allows remote operation of trains at local or remote layouts, optionally connecting it to video conferencing software like Google Meet or Zoom.

Goals

  1. Easy to set up and maintain.
  2. Easy to access the cab view via a URL or via conference software eg. Zoom or Meet.
  3. Distribute the setup to others for the betterment of the hobby.
  4. Provide a low latency video stream to enable remote control via Engine Driver/WiThrottle
  5. Keep the hardware within HO NMRA clearances.
  6. Use commonly available components and open-source software where possible.

Implementation

Hardware: We are using one Raspberry Pi Zero WH per CabCam car.

Camera: The Pi Zero Spy Camera works well for our purposes.

Software: The project uses Raspian Buster running MJPG Streamer on the CabCam car. This streams video from a URL on the local network. The video can be viewed locally or streamed to conference software via OBS and the OBS VirtualCam plugin.

Power: The Juiceb0x Zero is a “hat” for the Pi Zero. While the Pi Zero WH comes with the required header already installed, soldering is required to install header pins on the Juiceb0x Zero board.

Rolling Stock: The easiest approach is build a mounting sled out of styrene as shown below. With a little bit more work the setup can be installed inside a dummy engine, too.

IMG_20200710_191346

How To

This section describes the setup in more detail. Some familiarity with Raspberry Pi and respective software management is helpful.

1. Gathering the hardware

You will need:

2. Setting up the hardware

Connect the camera to the Pi Zero WH. Solder the header pins to the Juiceb0x Zero per the instructions that come with it and attach it to the Pi Zero WH. Connect the battery to the Juiceb0x Zero. Connect the USB charger to the Juiceb0x Zero to charge the battery.

Never connect power to the USB ports of the Pi Zero WH while the Juiceb0x Zero is attached. 

3. Burning the image and setting up the software

Download and install the Raspberry Pi Imager, formerly called NOOBS. 

Run the software and select Choose OS, then Raspberry Pi OS (Other) and select Raspberry Pi OS Lite.
Next Select your SD Card via Choose SD Card and hit Write. Once it is done writing, eject and reinsert the SD card into your computer.

4. WiFi Setup

Now we will configure wifi for your home or club network. With a text editor create (or edit) a file named wpa_supplicant.conf in the /etc/wpa_supplicant/ folder on the SD card. Paste the following text to this file.

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
      ssid="NETWORK-NAME"
      psk="NETWORK-PASSWORD"
}

Change the country code to your two character country code per the  ISO 3166 alpha-2 country code. For many of us it will likely be US or GB. SSID refers to your wifi network name and PSK is your network’s password. Save this file and safely eject the SD card. 

Remove the SD card from your computer, insert it into the Pi, and power up the Pi by moving the small slider switch on the Juiceb0x Zero to On. The blue LED on the Juiceb0x Zero should light up, and you should see flashing green lights. Some cameras have LEDs on the connector strip, those should light up briefly as well. Give the Pi about two minutes to boot up. 

5. Logging in to the Pi

Find the IP address your Pi is using and log in using ssh as user pi.

The default password is raspberry.

On a Mac use Terminal. On Windows use PuTTY (you may have to download it)  and put in the IP of your Pi in the Hostname block. When you connect, the default username is pi and the password is raspberry.

On many networks the following also works:

ssh pi@raspberrypi.local

6. Configuring the Pi

Once on the Pi command line type

sudo raspi-config

to enter the configuration page for the Pi. First enter Change User Password and enter a new password if you want to secure the device. Next enter Network Options, select Hostname, and give your Pi a unique name like LayoutCabCam1 or similar. This is helpful to identify which Pi is which if your network supports hostnames. Next select Interfacing Options, select P1 Camera, and enable the camera interface. The last thing to do in the configurator is to expand the file system. Go to Advanced and select A1 Expand Filesystem. After that finishes, exit the configurator and allow the Pi to reboot. 

7. Configuring MJPG Streamer

Now we are going to configure the software to allow us to stream the cab POV. 

Log back into your Pi and run the following commands

sudo apt-get update
sudo apt-get upgrade

Follow this with

sudo apt-get install git 
sudo apt-get install cmake libjpeg8-dev -y
sudo apt-get install gcc g++ -y

This will take a while.

Run the following commands to clone and compile MJPG Streamer, this will also take some time. 

git clone https://github.com/jacksonliam/mjpg-streamer
cd mjpg-streamer/mjpg-streamer-experimental

make && sudo make install

Sit back for a bit and enjoy a drink.

Next run

mjpg_streamer -i "input_raspicam.so" -o "output_http.so"

to test the stream with the most basic settings. This should output some stuff on your terminal to let you know it is working. Point the browser on your computer  to http://IP:8080?action=stream (replace IP with the IP address for the Pi from earlier). If you see output from your camera you are ready to move on. In the terminal, hit Ctrl+C to close the stream.

The following command uses the parameters we set at SVL.

mjpg_streamer -i "input_raspicam.so -x 640 -y 480 -fps 15" \-o "output_http.so"

The Internet uplink bandwidth at SVL is quite limited. For cab control with remote operators we found that SD resolution is sufficient and limits bandwidth demand. We are using a frame rate of 15 images per second. The stream doesn’t get smoother turning this up, it only gets darker. If your camera is upside down you may need to insert -rot 180 before -fps.

We want to turn on the stream at on startup. A small startup script will get us there.

Enter the following

sudo nano /home/pi/startcam.sh 

Enter the following in the text editor.

#!/bin/bash

mjpg_streamer \

-i "input_raspicam.so -x 640 -y 480 -rot 180 -fps 15" \
-o “output_http.so”

Hit CTRL+X to leave the editor, hit Y and  Enter to write the file to the SD card. 

Make this file executable with

sudo chmod a+x /home/pi/startcam.sh

To cause the camera stream to start whenever the Pi boots, edit the /etc/rc.local file. To do this run

sudo nano /etc/rc.local

and add /home/pi/startcam.sh close to the bottom of the file right above the exit 0 command. Exit the editor with CTRL+X Y Enter.

Reboot the Pi with sudo shutdown -r now. After reboot you should be able to see the stream in your browser at the URL you used above. After placing the camera on a flatcar, it should look something like this.

Put your CabCam car on the front of a train, and run the train while watching the video stream in the browser.

Bernhard wrote down some thoughts on camera placement and car choice on his blog.

9. What’s Next?

To stream the video to remote operators we use OBS with the VirtualCam plugin, configured with CabCam feeds. This is connected to Google Meet and can even stream to Youtube Live. Other video conferencing software like Zoom, Duo, Skype, etc. can be used, too. Remote operators join the video conference and use Engine Driver or WiThrottle to control trains via JMRI. We’ll cover that in a separate post.

Variations

Hardware: While we are using a Raspberry Pi Zero WH, any Pi with built-in Wifi will work.

Camera: Any compatible Raspberry Pi camera can be made to work. Possible options are the official Pi camera, the spy cameras, or other compatible cameras available from e.g. Adafruit.

Power: The Zero2Go board is an alternative to the Juiceb0x Zero. However, the Zero2Go can’t charge the battery. In either case, do not power the Pi from the onboard USB while the power solution board is attached.

Some people had success with using a small form-factor USB power bank connected to a Pi Zero without additional hardware.

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