/**
* Generate a wav file given the $letters in the code
* @todo Add ability to merge 2 sound files together to have random background sounds
* @param array $letters
* @return string The binary contents of the wav file
*/
protected function generateWAV($letters)
{
$wavCaptcha = new WavFile();
$first = true;
// reading first wav file
foreach ($letters as $letter) {
$letter = strtoupper($letter);
try {
$l = new WavFile($this->audio_path . '/' . $letter . '.wav');
if ($first) {
// set sample rate, bits/sample, and # of channels for file based on first letter
$wavCaptcha->setSampleRate($l->getSampleRate())->setBitsPerSample($l->getBitsPerSample())->setNumChannels($l->getNumChannels());
$first = false;
}
// append letter to the captcha audio
$wavCaptcha->appendWav($l);
// random length of silence between $audio_gap_min and $audio_gap_max
if ($this->audio_gap_max > 0 && $this->audio_gap_max > $this->audio_gap_min) {
$wavCaptcha->insertSilence(mt_rand($this->audio_gap_min, $this->audio_gap_max) / 1000.0);
}
} catch (Exception $ex) {
// failed to open file, or the wav file is broken or not supported
// 2 wav files were not compatible, different # channels, bits/sample, or sample rate
throw $ex;
}
}
/********* Set up audio filters *****************************/
$filters = array();
if ($this->audio_use_noise == true) {
// use background audio - find random file
$noiseFile = $this->getRandomNoiseFile();
if ($noiseFile !== false && is_readable($noiseFile)) {
try {
$wavNoise = new WavFile($noiseFile, false);
} catch (Exception $ex) {
throw $ex;
}
// start at a random offset from the beginning of the wavfile
// in order to add more randomness
$randOffset = 0;
if ($wavNoise->getNumBlocks() > 2 * $wavCaptcha->getNumBlocks()) {
$randBlock = mt_rand(0, $wavNoise->getNumBlocks() - $wavCaptcha->getNumBlocks());
$wavNoise->readWavData($randBlock * $wavNoise->getBlockAlign(), $wavCaptcha->getNumBlocks() * $wavNoise->getBlockAlign());
} else {
$wavNoise->readWavData();
$randOffset = mt_rand(0, $wavNoise->getNumBlocks() - 1);
}
$mixOpts = array('wav' => $wavNoise, 'loop' => true, 'blockOffset' => $randOffset);
$filters[WavFile::FILTER_MIX] = $mixOpts;
$filters[WavFile::FILTER_NORMALIZE] = $this->audio_mix_normalization;
}
}
if ($this->degrade_audio == true) {
// add random noise.
// any noise level below 95% is intensely distorted and not pleasant to the ear
$filters[WavFile::FILTER_DEGRADE] = mt_rand(95, 98) / 100.0;
}
if (!empty($filters)) {
$wavCaptcha->filter($filters);
// apply filters to captcha audio
}
return $wavCaptcha->__toString();
}
/**
* Generate a wav file given the $letters in the code
*
* @param array $letters The letters making up the captcha
* @return string The audio content in WAV format
*/
protected function generateWAV($letters)
{
$wavCaptcha = new WavFile();
$first = true;
// reading first wav file
if ($this->audio_use_sox && !is_executable($this->sox_binary_path)) {
throw new Exception("Path to SoX binary is incorrect or not executable");
}
foreach ($letters as $letter) {
$letter = strtoupper($letter);
try {
$letter_file = realpath($this->audio_path) . DIRECTORY_SEPARATOR . $letter . '.wav';
if ($this->audio_use_sox) {
$sox_cmd = sprintf("%s %s -t wav - %s", $this->sox_binary_path, $letter_file, $this->getSoxEffectChain());
$data = `{$sox_cmd}`;
$l = new WavFile();
$l->setIgnoreChunkSizes(true);
$l->setWavData($data);
} else {
$l = new WavFile($letter_file);
}
if ($first) {
// set sample rate, bits/sample, and # of channels for file based on first letter
$wavCaptcha->setSampleRate($l->getSampleRate())->setBitsPerSample($l->getBitsPerSample())->setNumChannels($l->getNumChannels());
$first = false;
}
// append letter to the captcha audio
$wavCaptcha->appendWav($l);
// random length of silence between $audio_gap_min and $audio_gap_max
if ($this->audio_gap_max > 0 && $this->audio_gap_max > $this->audio_gap_min) {
$wavCaptcha->insertSilence(mt_rand($this->audio_gap_min, $this->audio_gap_max) / 1000.0);
}
} catch (Exception $ex) {
// failed to open file, or the wav file is broken or not supported
// 2 wav files were not compatible, different # channels, bits/sample, or sample rate
throw new Exception("Error generating audio captcha on letter '{$letter}': " . $ex->getMessage());
}
}
/********* Set up audio filters *****************************/
$filters = array();
if ($this->audio_use_noise == true) {
// use background audio - find random file
$wavNoise = false;
$randOffset = 0;
/*
// uncomment to try experimental SoX noise generation.
// warning: sounds may be considered annoying
if ($this->audio_use_sox) {
$duration = $wavCaptcha->getDataSize() / ($wavCaptcha->getBitsPerSample() / 8) /
$wavCaptcha->getNumChannels() / $wavCaptcha->getSampleRate();
$duration = round($duration, 2);
$wavNoise = new WavFile();
$wavNoise->setIgnoreChunkSizes(true);
$noiseData = $this->getSoxNoiseData($duration,
$wavCaptcha->getNumChannels(),
$wavCaptcha->getSampleRate(),
$wavCaptcha->getBitsPerSample());
$wavNoise->setWavData($noiseData, true);
} else
*/
if (($noiseFile = $this->getRandomNoiseFile()) !== false) {
try {
$wavNoise = new WavFile($noiseFile, false);
} catch (Exception $ex) {
throw $ex;
}
// start at a random offset from the beginning of the wavfile
// in order to add more randomness
$randOffset = 0;
if ($wavNoise->getNumBlocks() > 2 * $wavCaptcha->getNumBlocks()) {
$randBlock = mt_rand(0, $wavNoise->getNumBlocks() - $wavCaptcha->getNumBlocks());
$wavNoise->readWavData($randBlock * $wavNoise->getBlockAlign(), $wavCaptcha->getNumBlocks() * $wavNoise->getBlockAlign());
} else {
$wavNoise->readWavData();
$randOffset = mt_rand(0, $wavNoise->getNumBlocks() - 1);
}
}
if ($wavNoise !== false) {
$mixOpts = array('wav' => $wavNoise, 'loop' => true, 'blockOffset' => $randOffset);
$filters[WavFile::FILTER_MIX] = $mixOpts;
$filters[WavFile::FILTER_NORMALIZE] = $this->audio_mix_normalization;
}
}
if ($this->degrade_audio == true) {
// add random noise.
// any noise level below 95% is intensely distorted and not pleasant to the ear
$filters[WavFile::FILTER_DEGRADE] = mt_rand(95, 98) / 100.0;
}
if (!empty($filters)) {
$wavCaptcha->filter($filters);
// apply filters to captcha audio
}
return $wavCaptcha->__toString();
}
