Klogskabet - Audio player

Description

This is a simple Node.js app for the Klogskabet audio module. It wraps an mpg123 process to play the MP3 audio files assigned to it in the Klogskabet CMS.

The code specifically targets a Raspberry Pi 3 running Raspbian "stretch", using a JustBoom DAC hat for audio output.

Requirements

Raspbian "stretch"
Node.js 8.x & npm
mpg123

Installation

NOTE: The following assumes you're running a regular Raspberry Pi with a passwordless-sudo pi user account. The config files for this app assumes the app will be installed in /home/pi/klogskabet-audio-player/.

Of course it also assumes that the audio module has been built as specified.

First, if you haven't already, install the JustBoom DAC hardware and enable its device tree overlay (see also JustBoom's docs), by editing /boot/config.txt (e.g. with $ sudo nano /boot/config.txt):

Change the line dtparam=audio=on to dtparam=audio=off
Add the line dtoverlay=justboom-dac

Next, install dependencies (Node.js 8.x, device-tree compiler, and mpg123):

$ curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
$ sudo apt-get update
$ sudo apt-get install -y nodejs build-essential device-tree-compiler mpg123

Download or clone this source code, and cd into the /home/pi/klogskabet-audio-player directory (if you've downloaded a .zip from GitHub, you may have to rename the directory to get rid of the branch name).

$ cd klogskabet-audio-player

Compile the device-tree-overlay for the buttons, and move it to /boot/overlays/:

$ dtc -W no-unit_address_vs_reg -@ -I dts -O dtb -o ./devicetree/klogskabet-audio-buttons.dtbo ./devicetree/klogskabet-audio-buttons.dts
$ sudo cp ./devicetree/klogskabet-audio-buttons.dtbo /boot/overlays/klogskabet-audio-buttons.dtbo
$ sudo chown root:root /boot/overlays/klogskabet-audio-buttons.dtbo

Install the overlay by editing /boot/config.txt again and add the line dtoverlay=klogskabet-audio-buttons.

Install npm packages

$ npm install

Set up the device's ID for use with the CMS by copying the example config, and editing it:

$ cp config/device.js.example config/device.js
$ nano config/device.js

Reboot the Raspberry Pi:

$ sudo reboot

Test the setup by issuing:

$ sudo node index.js

Provided everything works, perform these final two steps to make the app start automatically and manage log files:

Install the logrotate configuration:

$ sudo cp ./config/klogskabet-audio-player.logrotate /etc/logrotate.d/klogskabet-audio-player.logrotate
$ sudo chmod 0644 /etc/logrotate.d/klogskabet-audio-player.logrotate
$ sudo chown root:root /etc/logrotate.d/klogskabet-audio-player.logrotate

And install the systemd service script:

$ sudo cp ./config/klogskabet-audio-player.service /lib/systemd/system/klogskabet-audio-player.service
$ sudo systemctl daemon-reload
$ sudo systemctl enable klogskabet-audio-player.service

Reboot the Pi to ensure it starts up automatically. If you need to stop it when it's running as a service, you can issue:

$ sudo systemctl stop klogskabet-audio-player.service

And conversely, to start it again:

$ sudo systemctl start klogskabet-audio-player.service

Overview

The app loads a playlist of MP3 files from the Klogskabet CMS, and loops through it.

Three GPIO-connected buttons allow users to skip to the next/previous track, and play/pause the current track.

Player API

The player is rather simple:

Methods

`Player#load(filePath) => undefined`

Load and play the given file

`Player#loadPaused(filePath) => undefined`

Load - but don't auto-play - the given file

`Player#playPause() => undefined`

Toggle pause. Note that pausing might seem "delayed" slightly. This is mpg123's fault; it doesn't clear the audio buffer when pausing, so anything already in there will play.

`Player#quit() => undefined`

Quit the mpg123 process. Note that if this is called, the player object becomes pretty usable.

Properties

`Player#state => number`

A number describing the state:
0: Stopped (no track loaded)
1: Paused (track loaded)
2: Playing

`Player#isPlaying => boolean`

Whether anything is being played.

`Player#elapsed => number`

Get elapsed time in seconds.

`Player#remaining => number`

Get remaining time in seconds.

Events

`playing`

State changed to playing.

`paused`

State changed to paused.

`stopped`

Playback stopped.

`statechange: number`

State (playing/paused/stopped) changed. Listeners receive the new state number. This is emitted before the specfic paused/playing/stopped events.

`timestamp: number, number`

Elapsed/remaining time updated. Listeners receive both values as numbers. The values may be negative, indicating nothing's playing.

`error: message`

mpg123 spat out an error. Listeners receive the error text.

Development

The version number in package.json should be bumped for new releases (and npm install should be run to update package-lock.json before committing!).

Known issues

Pausing is "delayed" slightly, as mpg123 doesn't clear already-buffered audio when pausing, so that has to play through.

Committing

Adhere to the git-flow model for branching etc..

Version history

1.1.0

Added server check-in to report IP addresses, and more robust file downloading.

1.0.0

Initial release.

License

See COPYING

yokecph / klogskabet-audio-player Goto Github PK