Streamed processing

.env.example

@@ -0,0 +1,3 @@
+PIFM_PATH=/home/pi/PiFmRds/src/pi_fm_rds
+NODE_ENV=production
+HOST=localhost

README.md

@@ -7,4 +7,32 @@ mpd2fm tracks *tinyfm* tracks and turn them into FM modulations.
 # Requirements
 
 - a [Raspberry Pi with an antenna/metalic wire](http://makezine.com/projects/make-38-cameras-and-av/raspberry-pirate-radio/#steppers);
-- a [tinyfm sandbox](https://github.com/tinyfm/sandbox)-like Pi configuration;
+- a [tinyfm sandbox](https://github.com/tinyfm/sandbox)-like Pi configuration;
+
+# Install
+
+```bash
+npm install -g git+https://github.com/tinyfm/mpd2fm.git
+```
+
+# Usage
+
+Use `mpd2fm --help` to display help about available commands.
+
+## init.d config
+
+Prints out the Debian `initd` config.
+
+```bash
+mpd2fm --initd-config
+```
+
+Pretty much handy to daemonize the command-line tool on a Raspberry Pi.
+
+## Playback events to FM
+
+Listens to tinyfm audio playback events (backed by [mopidy](https://www.mopidy.com/)) and broadcasts them as an FM signal.
+
+```
+mpd2fm --base-dir /usr/share/tinyfm --start
+```

bin/cli.js

@@ -0,0 +1,57 @@
+#!/usr/bin/env node
+
+'use strict';
+
+var fs = require('fs');
+var path = require('path');
+var Mopidy = require('mopidy');
+var encoder = require('../lib/encoder');
+
+var argv = require('yargs')
+  .options('initd-config', {
+    alias: 'i',
+    boolean: true,
+    default: false,
+    description: 'Displays out the related Debian initd script.'
+  })
+  .options('base-dir', {
+    alias: 'd',
+    default: '/usr/share/tinyfm',
+    description: 'Base directory to resolve event media filepath from.'
+  })
+  .options('start', {
+    boolean: true,
+    default: false,
+    description: 'Starts to media playback to FM broadcasting server.'
+  })
+  .strict()
+  .argv;
+
+if (argv.initdConfig) {
+  return fs.createReadStream(path.join(__dirname, '..', 'dist', 'init.d', 'mpd2fm'))
+    .pipe(process.stdout);
+}
+
+if (argv.start) {
+  var mopidy = new Mopidy({
+    callingConvention: 'by-position-or-by-name',
+    webSocketUrl: 'ws://' + (process.env.HOST || 'localhost') + ':6680/mopidy/ws/'
+  });
+
+  var broadcast = encoder({ baseDir: argv.baseDir, env: 'test' });
+  var currentStream;
+
+  mopidy.on("event:trackPlaybackStarted", function (event) {
+    // catch the uri
+    var filepath = event.tl_track.track.uri.split(":").pop();
+    console.log("-----------------------------------");
+    console.log("New song:", filepath);
+
+    currentStream = broadcast(filepath);
+  }, logErrors);
+}
+
+
+function logErrors(err){
+  console.error(err);
+}

bin/test.js

@@ -0,0 +1,17 @@
+'use strict';
+
+/*
+ This test case demonstrates our ability to swap a stream with another one.
+
+ $ node bin/test.js audioFile1.wav audioFile2.wav
+
+ It will play an audio file and swap with a second audio file a second later.
+ */
+
+var broadcast = require('../lib/encoder')({ env: 'test' });
+
+broadcast(process.argv[2]);
+
+setTimeout(function(){
+  broadcast(process.argv[3])
+}, 1000);

dist/init.d/mpd2fm

@@ -6,17 +6,17 @@
 # Default-Start:     2 3 4 5
 # Default-Stop:      0 1 6
 # Short-Description: tinyfm audio playback to FM transmission.
-# Description:       
+# Description:       tinyfm audio playback to FM transmission.
 ### END INIT INFO
 
 # Author: tinyfm
 
 # PATH should only include /usr/* if it runs after the mountnfs.sh script
-PATH=/sbin:/usr/sbin:/bin:/usr/bin
-DESC="Description of the service"
+PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/bin
+DESC=tinyfm audio playback to FM transmission."
 NAME=mpd2fm
-DAEMON=/usr/local/bin/node
-DAEMON_ARGS="/home/pi/mpd2fm/script.js"
+DAEMON=$(which mpd2fm)
+DAEMON_ARGS="--start"
 PIDFILE=/var/run/$NAME.pid
 SCRIPTNAME=/etc/init.d/$NAME
 

lib/encoder.js

@@ -0,0 +1,55 @@
+'use strict';
+
+var child_process = require('child_process');
+var path = require('path');
+var fs = require('fs');
+
+// path is expected to be something like /home/pi/PiFmRds/src/pi_fm_rds (on a tinyfm vanilla install)
+var pifmPath = process.env.PIFM_PATH || path.join('/', 'home', 'pi', 'PiFmRds', 'src', 'pi_fm_rds');
+var activeStream;
+
+module.exports = function(options){
+  var resolvedOptions = options || {};
+  var pipeline = resolveStreamer(resolvedOptions.env || process.env.NODE_ENV || null);
+
+  return function streamFrom(filepath){
+    clearStream(function(){
+      var resolvedFilepath = path.resolve(resolvedOptions.baseDir, filepath);
+      var stream = fs.createReadStream(resolvedFilepath);
+
+      stream.pipe(pipeline.stdin);
+
+      return stream;
+    });
+  };
+};
+
+function clearStream(fn){
+  if (activeStream){
+    activeStream.unpipe();
+
+    activeStream.close(function(){
+      activeStream = fn();
+    });
+  }
+  else {
+    process.nextTick(function(){
+      activeStream = fn();
+    });
+  }
+}
+
+function resolveStreamer(env){
+  var args = [];
+
+  if (env !== 'production'){
+    args = ['play', ['-']];
+  }
+  else {
+    var pifmPath = require.resolve(pifmPath);
+
+    args = [pifmPath, ["-audio", "-"]];
+  }
+
+  return child_process.spawn.apply(child_process, args);
+}

package.json

@@ -2,10 +2,14 @@
   "name": "mpd2fm",
   "version": "1.0.0",
   "description": "tinyfm mdp to FM transmitter bridge.",
-  "main": "index.js",
+  "main": "./lib/encoder.js",
   "dependencies": {
     "mopidy": "^0.4.1",
-    "when": "^3.6.3"
+    "when": "^3.6.3",
+    "yargs": "^1.3.3"
+  },
+  "bin": {
+    "mpd2fm": "./bin/cli.js"
   },
   "devDependencies": {},
   "scripts": {