DurationHelper.php

<?php

// Needs PHP-FFMpeg

namespace App\Helpers;

use FFMpeg\Coordinate\TimeCode;

class DurationHelper
{
    private int|float $seconds;

    private int $splitDuration;

    public array $intervals;

    public array $segments;

    public function __construct(int|float $seconds, int $splitDuration)
    {
        $this->seconds = $seconds;
        $this->splitDuration = $splitDuration;
        $this->setIntervals();
        $this->setSegments();
    }

    public static function segments(int|float $seconds): array
    {
        return (new self($seconds))->segments;
    }

    public static function intervals(int|float $seconds): array
    {
        return (new self($seconds))->intervals;
    }

    private function setSegments(): void
    {

      foreach(range(1, $this->intervals['whole']) as $index => $value) {
        $this->segments[] = $this->segmentItem( $this->startingPoint($index), $this->splitDuration);
      }

       $this->insertLastSegment();
    }

    public function insertLastSegment(): void
    {
        if (0 !== $this->intervals['fractionSeconds']) {
            $this->segments[] = $this->segmentItem( $this->endingPoint(), $this->intervals['fractionSeconds']);
        }
    }

    private function setIntervals(): void
    {
        $totalSeconds = (int) $this->seconds;

        $segments = $totalSeconds / $this->splitDuration;
        $whole = (int) $segments;
        $wholeSeconds = $whole * $this->splitDuration;

        $fraction = $segments - $whole;
        $fractionSeconds = $totalSeconds - $wholeSeconds;

        $this->intervals = [
            'whole' => $whole,
            'fraction' => $fraction,
            'totalSeconds' => $totalSeconds,
            'wholeSeconds' => $wholeSeconds,
            'fractionSeconds' => $fractionSeconds,
        ];
    }

    private function startingPoint(int $segment): string
    {
        return $segment * $this->splitDuration;
    }

    private function endingPoint(): string
    {
        return $this->intervals['totalSeconds'] - $this->intervals['fractionSeconds'];
    }

    private function segmentItem(int $start, int $duration)
    {
        return [
          'start' => (string) TimeCode::fromSeconds($start), 
          'duration' => (string) TimeCode::fromSeconds($duration)
        ];
    }
}