SrtParser\srtFile::sync PHP Метод

    public function sync($startIndex, $startTime, $endIndex, $endTime, $syncLast = true)
    {
        $keys = array_keys($this->subs);
        $sub_count = sizeof($keys);
        //set first and last subtitles index
        if (!$startIndex) {
            $startIndex = 0;
        }
        if (!$endIndex) {
            $endIndex = $sub_count - 1;
        }
        //check subtitles do exist
        $startSubtitle = $this->getSub($startIndex);
        $endSubtitle = $this->getSub($endIndex);
        if (!$startSubtitle || !$endSubtitle) {
            return false;
        }
        if (!($startTime < $endTime)) {
            return false;
        }
        $shift = $startTime - $startSubtitle->getStart();
        $factor = ($endTime - $startTime) / ($endSubtitle->getStart() - $startSubtitle->getStart());
        /* Shift subtitles to the start point */
        if ($shift) {
            $this->shift($shift, $startIndex, $endIndex);
        }
        /* Sync timings with proportion */
        for ($index = $startIndex; $index <= $endIndex; $index++) {
            $entry = $this->getSub($index);
            $entry->scale($startTime, $factor);
        }
        return true;
    }