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Using PHP to Read the Contents of a Folder

  • Episode 326
  • December 17, 2013
Chat Logs Download Video (734.17 MB) Download MP3 (56.35 MB) Donate

Robbie starts the development of a PHP tool to read all MIDI files from a folder and play them.

Topics Covered:

  • {play 4:07}Prize Giveaway: $25 prepaid Visa card from ESET.
  • {play 5:48}Happy birthday wishes.
  • Watch O Holy Night with Robbie and Carrie Webb, accompanied by Eric Kidd and Christina Skala.
  • {play 9:15}Thank you to all who have supported the show. Announcing our new crowdfunding campaign where you get a gift card of your choice in the same monetary value of your donation.
  • {play 11:35}Eric signs Robgor's 8x10.
  • {play 16:03}Featured Viewer Question: I have a Raspberry Pi controlling my Christmas lights, synchronized to music. I'd like to be able to control which MIDI file is playing from any computer on my network with a PHP script. How can this be done?
    • First, we need the php5 package installed via apt-get, which gives us PHP and a running Apache server.
    • Using PHP's opendir() along with readdir() to load a list of files from our MIDI storage folder.
    • Determining which ports you can use for aplaymidi.
    • Playing midi files on Linux using aplaymidi.
    • Assigning the song names to an array for security reasons.
    • Piping all output to /dev/null and returning control to our script to avoid it hanging up while a song plays.
    • Creating a form which allows us to select and play any MIDI file in our MIDI storage folder.
    • Note: We did not get any playback because of a PulseAudio issue. The script works as is! All we had to do was run this command (where Apache is running as the www-data user:
      sudo usermod -a -G pulse-access www-data
    • The final, working script (as written on the show):
      &lt?php
        ///////////////////////////////////////////////////////////////////////////
        // This script was written live on Category5 Technology TV episode 326.  //
        // Check out the episode at http://www.category5.tv/episodes/326.php     //
        // Note: While live on the air, we couldn't get it to play--turns out    //
        //       it was a pulseaudio issue, fixed with the following command...  //
        //       Assuming your apache (like ours) is running as www-data user,   //
        //       and that your system is using PulseAudio, make it go with:      //
        //       sudo usermod -a -G pulse-access www-data                        //
        //       MAY BE A GOOD IDEA TO REBOOT at that point, just to be sure...  //
        ///////////////////////////////////////////////////////////////////////////
        
        $folder = './mid';
        if ($handle = opendir($folder)) {
          while (false !== ($entry = readdir($handle))) {
            if (stristr($entry, '.mid')) {
              $songs[] = $entry;
            }
          }
        }
      
        if (is_array($songs)) {
          foreach ($songs as $id => $song) {
            if ($_POST['song'] == $id) {
              exec('killall -9 aplaymidi');
              exec('aplaymidi -p 128 "' . $folder . '/' . $song . '" > /dev/null 2>/dev/null &');
            }
          }
      
          echo '<form method="post">';
          echo '<select name="song">';
          foreach ($songs as $id => $song) {
           echo '<option value="' . $id . '"> ' . $song . ' </option>' . PHP_EOL;
          }
          echo '</select>';
          echo '<input type="submit" value="Play" />';
          echo '</form>';
        }
      ?>
    • While adding the user to the pulse-access group makes the above script work, Robbie also described an alternative playback option: bypass the Apache user by instead outputting a script (/tmp/midi.sh) and running it by a cronjob. Here is an example of how that may be done, based on the above script. Only use this version if you truly cannot get the above script working.
      <?php
        ///////////////////////////////////////////////////////////////////////////
        // This script is a cronjob alternative as described on Category5        //
        // Technology TV episode 326 and based on the script created then.       //
        // Check out the episode at http://www.category5.tv/episodes/326.php     //
        // Note: this is built to be run alongside a cronjob as follows:         //
        //       */1 * * * * /tmp/midi.sh                                        //
        // midi.sh won't exist until you press play (it's automatically created) //
        // Due to the nature of cron, the song will start playing as late as     //
        // one minute after clicking "play".                                     //
        ///////////////////////////////////////////////////////////////////////////
        
        $folder = '/var/www/mid';
        if ($handle = opendir($folder)) {
          while (false !== ($entry = readdir($handle))) {
            if (stristr($entry, '.mid')) {
              $songs[] = $entry;
            }
          }
        } 
      
        $command = '#!/bin/bash' . PHP_EOL;
        if (is_array($songs)) {
          foreach ($songs as $id => $song) {
            if ($_POST['song'] == $id) {
              $command .= '/usr/bin/killall -9 aplaymidi' . PHP_EOL;
              $command .= '/usr/bin/aplaymidi -p 128:0 "' . $folder . '/' . $song . '" > /dev/null 2>/dev/null &' . PHP_EOL;
            }
          }
      
          $filename = '/tmp/midi.sh';
          $command .= 'rm -f ' . $filename;
          file_put_contents($filename, $command);
          exec('chmod +x ' . $filename);
          
          echo '<form method="post">';
          echo '<select name="song">';
          foreach ($songs as $id => $song) {
           echo '<option value="' . $id . '"> ' . $song . ' </option>' . PHP_EOL;
          }
          echo '</select>';
          echo '<input type="submit" value="Play" />';
          echo '</form>';
      }
      ?>
  • {play 51:18}Top Stories from the Category5.TV Newsroom
    • A Bitcoin startup has raised $25m in venture capital funding.
    • Game developers say they want YouTube to leave gameplay videos online even though they “technically” breach copyright.
    • A green supercomputer has been built at Cambridge University using just 1 Watt per 3,361 Mega-flops.
    • Xbox One key sequence to allow 360 games in fact bricks the console.
  • {play 57:51}SteamOS Beta has arrived! store.steampowered.com/steamos
  • {play 59:00}Giveaway: Yet another $25 preloaded Visa card from ESET.
  • {play 60:46}How to win a free copy of Telestream Wirecast 5 Pro.
  • {play 61:23}Greetings to our newly registered viewers!

  • Host: Robbie Ferguson
  • Co-Host: Eric Kidd

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