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CodeWithKyrianCodeWithKyrian
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Add Audio Util class and Feature Extractor
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Lines changed: 1533 additions & 52 deletions

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‎examples/composer.json‎

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"require": {
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"php": "^8.1",
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"symfony/console": "^7.0",
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"codewithkyrian/transformers": "*"
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"codewithkyrian/transformers": "*",
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"php-ffmpeg/php-ffmpeg": "dev-master"
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},
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"require-dev": {
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"symfony/var-dumper": "^7.0"

‎examples/image_detection.php‎

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‎examples/sounds/cat_meow.wav‎

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‎examples/sounds/dog_barking.wav‎

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‎src/DataStructures/FFT.php‎

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<?php
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declare(strict_types=1);
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namespace Codewithkyrian\Transformers\DataStructures;
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use SplFixedArray;
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class FFT
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{
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private bool $isPowerOfTwo;
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private NP2FFT|P2FFT $fft;
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public int $outputBufferSize;
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public function __construct(protected int $fftLength)
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{
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$this->isPowerOfTwo = self::isPowerOfTwo($fftLength);
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if ($this->isPowerOfTwo) {
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$this->fft = new P2FFT($fftLength);
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$this->outputBufferSize = 2 * $fftLength;
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} else {
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$this->fft = new NP2FFT($fftLength);
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$this->outputBufferSize = $this->fft->bufferSize;
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}
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}
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public function realTransform(SplFixedArray $out, SplFixedArray $input): void
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{
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$this->fft->realTransform($out, $input);
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}
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public function transform(SplFixedArray $out, SplFixedArray $input): void
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{
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$this->fft->transform($out, $input);
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}
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public static function isPowerOfTwo($n): bool
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{
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return ($n > 0) && (($n & ($n - 1)) == 0);
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}
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}

‎src/DataStructures/NP2FFT.php‎

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<?php
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declare(strict_types=1);
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namespace Codewithkyrian\Transformers\DataStructures;
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use Exception;
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use SplFixedArray;
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class NP2FFT
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{
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public int $bufferSize;
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private int $a;
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private $chirpBuffer;
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private $buffer1;
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private $buffer2;
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private $outBuffer1;
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private $outBuffer2;
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private $slicedChirpBuffer;
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private $f;
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/**
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* Constructs a new NP2FFT object.
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* @param int $fftLength The length of the FFT
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* @throws Exception
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*/
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public function __construct(int $fftLength)
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{
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// Helper variables
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$a = 2 * ($fftLength - 1);
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$b = 2 * (2 * $fftLength - 1);
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$nextP2 = pow(2, ceil(log($b, 2)));
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$this->bufferSize = $nextP2;
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$this->a = $a;
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// Define buffers
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// Compute chirp for transform
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$chirp = new SplFixedArray($b);
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$ichirp = new SplFixedArray($nextP2);
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$this->chirpBuffer = new SplFixedArray($nextP2);
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$this->buffer1 = new SplFixedArray($nextP2);
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$this->buffer2 = new SplFixedArray($nextP2);
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$this->outBuffer1 = new SplFixedArray($nextP2);
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$this->outBuffer2 = new SplFixedArray($nextP2);
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// Compute complex exponentiation
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$theta = -2 * M_PI / $fftLength;
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$baseR = cos($theta);
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$baseI = sin($theta);
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// Precompute helper for chirp-z transform
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for ($i = 0; $i < $b >> 1; ++$i) {
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// Compute complex power:
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$e = pow(($i + 1 - $fftLength), 2) / 2.0;
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// Compute the modulus and argument of the result
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$resultMod = pow(sqrt(pow($baseR, 2) + pow($baseI, 2)), $e);
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$resultArg = $e * atan2($baseI, $baseR);
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// Convert the result back to rectangular form
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// and assign to chirp and ichirp
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$i2 = 2 * $i;
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$chirp[$i2] = $resultMod * cos($resultArg);
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$chirp[$i2 + 1] = $resultMod * sin($resultArg);
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// conjugate
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$ichirp[$i2] = $chirp[$i2];
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$ichirp[$i2 + 1] = -$chirp[$i2 + 1];
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}
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$this->slicedChirpBuffer = SplFixedArray::fromArray(array_slice($chirp->toArray(), $a, $b - $a));
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// create object to perform Fast Fourier Transforms
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// with `nextP2` complex numbers
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$this->f = new P2FFT($nextP2 >> 1);
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$this->f->transform($this->chirpBuffer, $ichirp);
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}
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private function transform(SplFixedArray $output, SplFixedArray $input, bool $real = false): void
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{
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$ib1 = $this->buffer1;
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$ib2 = $this->buffer2;
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$ob2 = $this->outBuffer1;
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$ob3 = $this->outBuffer2;
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$cb = $this->chirpBuffer;
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$sb = $this->slicedChirpBuffer;
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$a = $this->a;
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if ($real) {
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// Real multiplication
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for ($j = 0; $j < count($sb); $j += 2) {
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$j2 = $j + 1;
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$j3 = $j >> 1;
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$aReal = $input[$j3];
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$ib1[$j] = $aReal * $sb[$j];
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$ib1[$j2] = $aReal * $sb[$j2];
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}
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} else {
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// Complex multiplication
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for ($j = 0; $j < count($sb); $j += 2) {
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$j2 = $j + 1;
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$ib1[$j] = $input[$j] * $sb[$j] - $input[$j2] * $sb[$j2];
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$ib1[$j2] = $input[$j] * $sb[$j2] + $input[$j2] * $sb[$j];
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}
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}
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$this->f->transform($ob2, $ib1);
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for ($j = 0; $j < count($cb); $j += 2) {
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$j2 = $j + 1;
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$ib2[$j] = $ob2[$j] * $cb[$j] - $ob2[$j2] * $cb[$j2];
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$ib2[$j2] = $ob2[$j] * $cb[$j2] + $ob2[$j2] * $cb[$j];
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}
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$this->f->inverseTransform($ob3, $ib2);
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for ($j = 0; $j < count($ob3); $j += 2) {
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$aReal = $ob3[$j + $a];
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$a_imag = $ob3[$j + $a + 1];
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$b_real = $sb[$j];
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$b_imag = $sb[$j + 1];
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$output[$j] = $aReal * $b_real - $a_imag * $b_imag;
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$output[$j + 1] = $aReal * $b_imag + $a_imag * $b_real;
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}
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}
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public function realTransform(SplFixedArray $output, SplFixedArray $input): void
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{
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$this->transform($output, $input, true);
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}
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}

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