kplay - A simple jukebox for the RaspberryPi

• flutter as frontend
• vlc as backend

Setup

🧰 Hardware Installation

• [Optional] Install cooling solution
• Connect Display to RasPi via DSI
  • see Waveshare
• Install HiFiBerry Digi2 Pro as GPIO hat
• [Optional] Connect Power Button to pins 5 and 6 of the GPIO (GPIO 3 and GND)

💾 Image Installation

Raspberry Pi Imager

• use Raspberry Pi OS Lite (64-bit)
• edit config with username, keyboard layout, wifi and enable ssh
• after writing image, open config.txt:
  • add to the end: dtoverlay=vc4-kms-dsi-waveshare-panel,7_0_inchC
  • add to the end: dtoverlay=hifiberry-digi-pro
  • Disable all audio cards (except hifiberry):
    • change dtparam=audio=on to dtparam=audio=off
    • change dtoverlay=vc4-kms-v3d to dtoverlay=vc4-kms-v3d,noaudio

⚙ System Setup

• run sudo raspi-config
  • Auto Login: System Options -> Auto Login
• Allow 3D acceleration: sudo usermod -a -G render [USER_NAME]
• Update system: sudo apt update
• Upgrade system: sudo apt full-upgrade
• [Optional] update firmware/bootloader: sudo rpi-eeprom-update -a

🍓 Install FlutterPi

• Install necessary libraries: sudo apt install git cmake libgl1-mesa-dev libgles2-mesa-dev libegl1-mesa-dev libdrm-dev libgbm-dev ttf-mscorefonts-installer fontconfig libsystemd-dev libinput-dev libudev-dev libxkbcommon-dev
• Update System Fonts: sudo fc-cache
• Clone FlutterPi: git clone --recursive https://github.com/ardera/flutter-pi
• Compile and Install FlutterPi:
  • Switch to flutter-pi directory: cd flutter-pi
  • Create build directory and switch to it: mkdir build && cd build
  • Build FlutterPi: cmake ..
  • Compile FlutterPi: make make -j`nproc`
  • Install FlutterPi: sudo make install

▶ Install kplay

• install jq for download parsing: sudo apt-get install jq
• Create kplay directory: mkdir ~/kplay
• Switch to directory: cd ~/kplay
• download latest release archive: curl -s https://api.github.com/repos/krush62/kplay/releases/latest | jq -r '(.assets[].browser_download_url | select(. | contains("tar.gz")))' | xargs wget {} -O kplay_release.tar.gz
• extract archive: tar -xzvf kplay_release.tar.gz
• delete archive rm kplay_release.tar.gz

⚙ Install Additional Tools for kplay

Library	Purpose
VLC	audio backend
ExifTool	retrieving audio metadata
FFMpeg	retrieve album art
Sqlite	library database
Chromium	displaying YouTube and YT-Music
XOrg	display server for showing chromium
XTerm	needed by startx/xinit to start with relative paths

• Install: sudo apt-get install vlc exiftool ffmpeg libsqlite3-dev chromium xorg xterm

⚙ Set up Scripts

• Create bin directory in home: mkdir ~/bin

Gesture Detection for exiting Chrome

• Install required python package: sudo apt install python3-evdev
• Find touchscreen name: python3 -m evdev.evtest
• copy gesture_detect.py to ~/bin, chmod +x ~/bin/gesture_detect.py
• check if the touchscreen name in script is the one detected above

Switch from Chrome to Application

• copy switch_from_chrome.sh to ~/bin, chmod +x ~/bin/switch_from_chrome.sh

Switch from Application to Chrome

• copy switch_to_chrome.sh to ~/bin, chmod +x ~/bin/switch_to_chrome.sh

Startup

• copy startup.sh to ~/bin, chmod +x ~/bin/startup.sh

Configure Autostart

• export bin path
  • Add this to the end of ~/.bashrc: export PATH="$HOME/bin:$PATH"
• copy bash_profile as .bash_profile to ~
• [Optional] remove not-used profile: rm ~/.profile (.bash_profile has exclusive priority)
• Reboot: sudo reboot now

Build

Build on Linux Machine

• Prepare for FlutterPi (one time only)
• Install SDK: Flutter Documentation to ~/flutter
• Export paths:
  • export PATH="$PATH:~/.pub-cache/bin"
  • export PATH="$PATH:~/flutter/bin" (if that's the flutter location)
• Install/Activate flutterpi_tool: flutter pub global activate flutterpi_tool
• Clone FlutterPi: git clone --recursive https://github.com/krush62/kplay
• build application normally and for FlutterPi:
  • cd kplay (project folder)
  • flutter build linux
  • flutterpi_tool build --arch=arm64 --cpu=pi4 --release
• copy bundle to target (Raspberry Pi):
  • scp -r build/flutter_assets/ [USER_NAME]@[RASPI_NAME]:/home/[USER_NAME]/kplay
  • [Optional] copy music data to target (from Windows/Linux)
  • scp -r "/path/to/music/folder" [USER_NAME]@[RASPI_NAME]:/home/[USER_NAME]/Music (or any other directory)

Energy Consumption

The energy consumption of the Raspberry Pi 4 B was measured using a cheap, little USB-C measuring device.

Activity	Brightness	Power
halt state (shut down)	---	1.5W
kplay (playing/paused)	255	3.6W
kplay (playing/paused)	128	3.1W
kplay (playing/paused)	5	2.7W
kplay (playing/paused)	0/off	2.6W
Youtube Music	255	3.8W
Youtube Music	128	3.2W
Youtube Music	5	2.8W
Youtube Music	0/off	2.7W

Saving Power

Commenting out the line arm_boost=1 and adding arm_freq=800 and gpu_freq=250 to /boot/firmware/config.txt reduces the power consumption by ~0.25W.