OSC-based audience participation

This was an installation project I did. A telephone number was projected on the wall and audience members would dial it. The Asterisk PBX I was running and gave an Interactive Voice Prompt to the person on the phone.

Once they were on the phone, various combinations of buttons would then change sound and light in the room.

Part of it also allowed members to play a game with each other, which would - again via OSC - control lights (talking to a DMX board) and sounds (triggers via MIDI) in the room.

So this is how the audience part of it went:

  1. User accesses address
  2. Browser is assigned a unique session
  3. Session ID (ID) is assigned to a team: ‘red’ or ‘blue’
  4. ID is assigned a random ‘strategy’ within a list of options
  5. User interacts with strategy via interface
  6. Interface ‘translates’ input to OSC, transmits to Pd
  7. User may be given a score/rank


We need a database and some backendy stuff.

Database bit first:

CREATE TABLE `scores` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(11) DEFAULT NULL,
  `score` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)

CREATE TABLE `state` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `x` tinyint(11) DEFAULT NULL,
  `y` tinyint(11) DEFAULT NULL,
  `z` tinyint(1) DEFAULT NULL,
  PRIMARY KEY (`id`)

CREATE TABLE `users` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `sid` varchar(32) DEFAULT NULL,
  `lasttime` int(11) DEFAULT NULL,
  `team` varchar(4) DEFAULT NULL,
  `model` int(11) DEFAULT NULL,
  `delta` int(11) unsigned NOT NULL,
  PRIMARY KEY (`id`)

Backend bit:


// Use Andy W. Schmeder's library <andy@a2hd.com>
require ('osc.php');


$db = mysql_connect("", "255", "j8qT9qrO") or die(mysql_error());
mysql_select_db("255", $db) or die(mysql_error());

function pointmod($uid, $team, $value) {
        // Ouick routine for updating scores, we'll need to redefine DB resource.

        $dba = mysql_connect("", "255", "j8qT9qrO") or die(mysql_error());
        mysql_select_db("255", $dba) or die(mysql_error());

        // Give users less points than their team as a whole.
        // Rounding with intval() will mess up scores if changes are less than division factor below.
        $uvalue = intval($value / 3);
        mysql_query(sprintf("UPDATE scores SET score=score+'%s' WHERE name='%s'", $value, $team), $dba);
        mysql_query(sprintf("UPDATE users SET delta=delta+'%s' WHERE sid='%s'", $uvalue, $uid), $dba);

// TODO: Purge users from DB older than 5 minutes
$time = time();

$id = session_id();

// Check if session already exists (i.e. we've seen the user before)
if ((mysql_num_rows(mysql_query(sprintf("SELECT * FROM users where sid='%s'", $id), $db))) == 0) {

        // Assign team to new user, even ID is blue, odd ID is red.
        if ((mysql_num_rows(mysql_query("SELECT * FROM users", $db))) == 0) {
                $team = "red";
        elseif ((mysql_num_rows(mysql_query("SELECT * FROM users", $db))) % 2 == 0) {
                $team = "blue";
        else {
                $team = "red";

        // Assign 'model' which corresponds to profile in Pd project
        // OSC path is /public/$model $buttonNumber, e.g. "/public/4 2"
        // Todo: Distribute users evenly, rather than completely at random
        $model = rand(1, 7);

        // Write all we want to store about the user to DB
        mysql_query(sprintf("INSERT INTO users(sid,lasttime,team,model)
                VALUES ('%s','%s','%s','%s')", $id, $time, $team, $model), $db);

} else {
        // Grab data (if user's already been seen) from DB
        $result = mysql_query("SELECT lasttime,team,model FROM users WHERE sid='$id'", $db);
        while($row = mysql_fetch_array($result)) {
                $lasttime = $row['lasttime'];
                $team = $row['team'];
                $model = $row['model'];

if ($_POST) {
        // Construct OSC packet for delivery to sound controller
        $c = new OSCClient();
        $c->set_destination("", 3890);
        $c->send(new OSCMessage("/public/$model", array($_POST['button'])));

        // Each strategy flips beween 'on' and 'off'.
        // Let's find out the status of the selected ($POST) strategy
        // TODO: Bug in SQL statement, if NULL, cannot compare to '0'.
        if (mysql_result(mysql_query(sprintf("SELECT z FROM state WHERE x='%s'
                AND y='%s'", $_POST['model'], $_POST['button']), $db), 0) == '1') {
                mysql_query(sprintf("UPDATE state SET z='0' WHERE x='%s' AND y='%s'",
                        $_POST['model'], $_POST['button']), $db);
        } else {
                mysql_query(sprintf("UPDATE state SET z='1' WHERE x='%s' AND y='%s'",
                        $_POST['model'], $_POST['button']), $db);

        $result = mysql_query("SELECT x, y, z FROM state", $db);
        while($states = mysql_fetch_array($result)) {
                $state[$states['x']][$states['y']] = $states['z'];

        // Matrix comparison.
        // There's probably a better way of defining these 'rules'
        switch ($state[$_POST['model']][$_POST['button']]) {
                case $state['1']['1']:
                pointmod($id, $team, '-10');

                // And so on ...

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<style type="text/css">
body {
#form .button {
        padding: 15px;
        margin: 5px;

<div style="padding:20px;margin:3px;width:80px;background-color:#<?php
        if ($team == "blue") {echo ("0000FF"); } else { echo ("FF0000"); } ?>">
<form id="form" name="form" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
  <input type="submit" name="button" id="1" value="1" tabindex="1" class="button" />
  <input type="submit" name="button" id="2" value="2" tabindex="2" class="button" />
  <input type="hidden" name="model" value="<?php echo $model; ?>">
<div style="padding:10px;margin:3px;width:80px;font-weight:800;color:#ddd;background-color:#660099;">
                // Get team score
                $score = mysql_query(sprintf("SELECT score FROM scores WHERE name='%s'", $team), $db);
                $row = mysql_fetch_row($score) or die(mysql_error());
                echo $row[0];
<div style="padding:10px;margin:3px;width:80px;font-weight:800;color:#ddd;background-color:#990066;">
                // Get user (session) score
                $score = mysql_query(sprintf("SELECT delta FROM users WHERE sid='%s'", $id), $db);
                $row = mysql_fetch_row($score) or die(mysql_error());
                echo $row[0];
<div style="padding:10px;margin:3px;width:80px;font-weight:800;color:#ddd;background-color:#669900;">
                // Cough up a short session ID (last 5 characters of $id)
                echo substr($id, -5);

All that’s left is the OSC part, which is actually taking that data and doing something useful with it. Behold: the patch.