Media Control Web Application

About

I made this web application to effortlessly control certain aspects of my home entertainment ecosystem using my phone. This application is mostly hard-coded around my specific use case and hardware. See Software and Hardware sections for usage.

Features

• Easily view, refresh, and change information about inputs at a glance
• Select between various HDMI inputs (using multi-port HDMI switch)
• Select between various USB ports for a single USB Hub input (using multi-port USB switch)
• Capture audio from HDMI devices and stream to wireless USB headset

Overview

The following image outlines the all the involved components and how the application ties in.

Software

Environment

• Raspbian (with root access to install services)
• Node.JS server

Languages/Scripts

• JavaScript (vanilla frontend, Node.JS backend)
• Python (used in backend to communicate with GPIO)
• Bash (used in backend to run services and execute scripts)

Setup Procedure

Note: Ensure hardware procedure is setup and tested first. cd into the root of this repo.

Audio Relay Service/Script:

• Update service/audio.sh to point to the right input and output devices
• Ensure the path to service/audio.sh in service/audrelay.service is correct
• Install the service: sudo cp service/audrelay.service /lib/systemd/system/audrelay.service

Node Application:

• npm install
• npm start
• The app will be running from localhost:3000 and can be used assuming hardware is setup properly

Hardware

Components

• HDMI Switch (Five inputs, one output)
• USB Switch (One input, four outputs)
• USB sound card with line-in
• HDMI line-out extractor
• Analog-Digital Converter (ADC: MCP3008)
• Relay Board (With two or more modules)
• Raspberry Pi Model B+
• Wireless USB headset

Setup Procedure

Triggering switches:

• To control the HDMI and USB switches remotely, the button presses need to be simulated from the Pi
• I soldered wires to the leads under the buttons and connected them to the relay board
  • One module for the HDMI switch and one for the USB switch
• To use the relay board with the Pi, I followed this video
• The script python/click.py triggers a relay module through a specified pin via command-line argument

Reading selected inputs:

• I used this guide to connect the understand the ADC pinout and connect it to the Pi.
• To tell which input is active in the switches, we can read the voltages of the leds.
• I soldered a wire to a lead of each of four of the five HDMI switch leds and three of the four USB switch leds.
  • Next I soldered each wire to a separate channel in the ADC.
• The script python/read.py should be updated to read the right channels and have an appropriate threshold for checking the voltages

Connecting everything together:

• Connect all the HDMI devices to the HDMI switch inputs
• Connect the HDMI switch output to the HDMI line-out extractor device
• Connect the HDMI line-out extractor to the TV and USB sound card accordingly
• Connect the USB sound card to the Pi
• Connect all the USB devices to the USB switch outputs
  • Connect whatever USB peripherals you wish to use between these devices to the input (in my case, the wireless USB headset)
• Provide power to all devices and ssh into the Pi (over wired or wireless network) to begin the software procedure.