Text to Speech with PHP (TTS)

A really quick and easy Text to Speech class for PHP that will generate an MP3 file. You can also easily setup an Ajax call on a website to play the text to speech audio file as you generate it. The quality is pretty good compared to other solutions but I haven’t figured out how to adjust pitch and tone or mix background music with it (yet.)

This is not really a solid solution for robust TTS as it relies on Google’s TTS API service; for more advanced solutions with lots of controls and embedding into videos we use Microsoft’s TTS system. But for easy to deploy and on demand web services this solution is a synch.

This Text to Speech with PHP version can be found on my CodeSlinger GitHub page.

<?php
/******************************************************************
Projectname:   PHP Text 2 Speech Class 
Version:       1.0 
Author:        Radovan Janjic <rade@it-radionica.com> 
Last modified: 11 06 2013 
Copyright (C): 2012 IT-radionica.com, All Rights Reserved 

* GNU General Public License (Version 2, June 1991) 
* 
* This program is free software; you can redistribute 
* it and/or modify it under the terms of the GNU
* General Public License as published by the Free
* Software Foundation; either version 2 of the License, 
* or (at your option) any later version.
* 
* This program is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the 
* implied warranty of MERCHANTABILITY or FITNESS FOR A 
* PARTICULAR PURPOSE. See the GNU General Public License 
* for more details. 

Description: 

PHP Text 2 Speech Class 

This class converts text to speech using Google text to  
speech API to transform text to mp3 file which will be  
downloaded and later used as eg. embed file.  

Example: 

****************************************************************** 
<?php
$t2s = new PHP_Text2Speech; 
?> 

// Simple example 
<audio controls="controls" autoplay="autoplay"> 
  <source src="<?php echo $t2s->speak('If you hear this sount it means that you are using PHP text to speech class.'); ?>" type="audio/mp3" /> 
</audio>

// Example use of other language 
<audio controls="controls" autoplay="autoplay"> 
  <source src="<?php echo $t2s->speak('Wie geht es Ihnen', 'de'); ?>" type="audio/mp3" /> 
</audio> 

******************************************************************/ 

class PHP_Text2Speech { 
     
    /** Max text characters
     * @var    Integer  
     */ 
    var $maxStrLen = 100; 
     
    /** Text len
     * @var    Integer  
     */ 
    var $textLen = 0; 
     
    /** No of words 
     * @var    Integer  
     */ 
    var $wordCount = 0; 
     
    /** Language of text (ISO 639-1) 
     * @var    String  
     * @link https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes 
     */ 
    var $lang = 'en'; 
     
    /** Text to speak 
     * @var    String  
     */ 
    var $text = NULL; 
     
    /** File name format 
     * @var    String  
     */ 
    var $mp3File = "%s.mp3"; 
     
    /** Directory to store audio file
     * @var    String  
     */ 
    var $audioDir = "audio/"; 

    /** Contents 
    * @var    String 
    */ 
    var $contents = NULL; 
     
    /** Function make request to Google translate, download file and returns audio file path 
     * @param     String     $text        - Text to speak 
     * @param     String     $lang         - Language of text (ISO 639-1) 
     * @return     String     - mp3 file path 
     * @link https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
     */ 
    function speak($text, $lang = NULL) { 
         
        if ($lang !== NULL) { 
            $this->lang = $lang; 
        } 

        // Create dir if not exists 
        if (!is_dir($this->audioDir)) { 
            mkdir($this->audioDir, 0755) or die('Could not create audio dir: ' . $this->audioDir); 
        } 
         
        // Try to set writing permissions for audio dir. 
        if (!is_writable($this->audioDir)) {  
            chmod($this->audioDir, 0755) or die('Could not set appropriate permissions for audio dir: ' . $this->audioDir); 
        } 
         
        // Can not handle more than 100 characters so split text 
        if (strlen($text) > $this->maxStrLen) {
            $this->text = $text;

            // Generate unique mp3 file name 
            $file = sprintf($this->mp3File, $this->audioDir . md5($this->text)); 
            if (!file_exists($file)) {
                $texts = array();
                $words = explode(' ', $this->text);
                $i = 0;
                $texts[$i] = NULL;
                foreach ($words as $w) {
                    $w = trim($w);
                    if (strlen($texts[$i] . ' ' . $w) < $this->maxStrLen) {
                        $texts[$i] = $texts[$i] . ' ' . $w;
                        if (preg_match('/[:;,.!?-]$/', $w)) { $i++; } // seperate at common breaks
                    } else {
                        $texts[++$i] = $w;
                    } 
                }

                // Get get separated files contents and marge them into one
                foreach ($texts as $txt) {
                    $pFile = $this->speak($txt, $this->lang); 
                    $this->contents .= $this->stripTags(file_get_contents($pFile)); 
                    unlink($pFile);
                }
                unset($words, $texts); 
                 
                // Save file
                file_put_contents($file, $this->contents); 
                $this->contents = NULL;
            }
        } else {
             
            // Generate unique mp3 file name 
            $file = sprintf($this->mp3File, $this->audioDir . md5($text)); 

            if (!file_exists($file)) { 
                // Text lenght 
                $this->textLen = strlen($text); 
                 
                // Words count 
                $this->wordCount = str_word_count($text); 

                // Encode string 
                $text = urlencode($text);

                // Download new file
                $this->download("http://translate.google.com/translate_tts?ie=UTF-8&q={$text}&tl={$this->lang}&total={$this->wordCount}&idx=0&textlen={$this->textLen}", $file);
            }
        } 
         
        // Returns mp3 file path 
        return $file; 
    } 
     
    /** Function to find the beginning of the mp3 file 
     * @param     String     $contents        - File contents 
     * @return     Integer 
     */  
    function getStart($contents) { 
        for($i=0; $i < strlen($contents); $i++){ 
            if(ord(substr($contents, $i, 1)) == 255){ 
                return $i; 
            } 
        } 
    } 
     
    /** Function to find the end of the mp3 file 
     * @param     String     $contents        - File contents 
     * @return     Integer 
     */  
    function getEnd($contents) { 
        $c = substr($contents, (strlen($contents) - 128)); 
        if(strtoupper(substr($c, 0, 3)) == 'TAG'){ 
            return $c; 
        }else{ 
            return FALSE; 
        } 
    } 

    /** Function to remove the ID3 tags from mp3 files 
     * @param     String     $contents        - File contents
     * @return     String
     */
    function stripTags($contents) {
        // Remove start
        $start = $this->getStart($contents);
        if ($start === FALSE) { 
            return FALSE;
        } else { 
            return substr($contents, $start);
        } 
        // Remove end tag 
        if ($this->getEnd($contents) !== FALSE){ 
            return substr($contents, 0, (strlen($contents) - 129));
        } 
    } 

    /** Function to download and save file 
     * @param     String     $url        - URL 
     * @param     String     $path         - Local path 
     */
    function download($url, $path) {  
        // Is curl installed? 
        if (!function_exists('curl_init')){ // use file get contents  
            $output = file_get_contents($url);
        }else{ // use curl  
            $ch = curl_init();  
            curl_setopt($ch, CURLOPT_URL, $url);  
            curl_setopt($ch, CURLOPT_AUTOREFERER, true);
            curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 5.1; rv:1.7.3) Gecko/20041001 Firefox/0.10.1");  
            curl_setopt($ch, CURLOPT_HEADER, 0);  
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
            curl_setopt($ch, CURLOPT_TIMEOUT, 10);
            $output = curl_exec($ch);  
            curl_close($ch);
        } 
        // Save file
        file_put_contents($path, $output);
    }
}

Here is an example of using the TTS class in PHP.

<?php
include 'PHP_Text2Speech.class.php';

$t2s = new PHP_Text2Speech;
?>

<audio controls="controls" autoplay="autoplay">
  <source src="<?php echo $t2s->speak('What are you looking at? Wipe that face off your head.'); ?>" type="audio/mp3" />
</audio>