/**
* @param resource $handle
*
* @return array
*/
protected static function parseDataSection($handle)
{
$data = ['id' => Helper::readString($handle, 4), 'size' => Helper::readLong($handle)];
if ($data['size'] > 0) {
$data['raw'] = fread($handle, $data['size']);
}
return $data;
}
/**
* @param string $note
* @param int $octave
* @param number $duration
*
* @return Sample
*/
public function note($note, $octave, $duration)
{
$result = new \SplFixedArray((int) ceil($this->getSampleRate() * $duration * 2));
$octave = min(8, max(1, $octave));
$frequency = Note::get($note) * pow(2, $octave - 4);
$attack = $this->generator->getAttack($this->getSampleRate(), $frequency, $this->getVolume());
$dampen = $this->generator->getDampen($this->getSampleRate(), $frequency, $this->getVolume());
$attackLength = (int) ($this->getSampleRate() * $attack);
$decayLength = (int) ($this->getSampleRate() * $duration);
for ($i = 0; $i < $attackLength; $i++) {
$value = $this->getVolume() * ($i / ($this->getSampleRate() * $attack)) * $this->getGenerator()->getWave($this->getSampleRate(), $frequency, $this->getVolume(), $i);
$result[$i << 1] = Helper::packChar($value);
$result[($i << 1) + 1] = Helper::packChar($value >> 8);
}
for (; $i < $decayLength; $i++) {
$value = $this->getVolume() * pow(1 - ($i - $this->getSampleRate() * $attack) / ($this->getSampleRate() * ($duration - $attack)), $dampen) * $this->getGenerator()->getWave($this->getSampleRate(), $frequency, $this->getVolume(), $i);
$result[$i << 1] = Helper::packChar($value);
$result[($i << 1) + 1] = Helper::packChar($value >> 8);
}
return new Sample($result->getSize(), implode('', $result->toArray()));
}
/**
* @param resource $handle
*/
protected function writeDataSection($handle)
{
Helper::writeString($handle, $this->dataSection->getId());
Helper::writeLong($handle, $this->dataSection->getSize());
Helper::writeString($handle, $this->dataSection->getRaw());
}
