<?php
namespace ProtoneMedia\LaravelFFMpeg\Exporters;
use Closure;
use Illuminate\Support\Collection;
use ProtoneMedia\LaravelFFMpeg\Filters\TileFilter;
class VTTPreviewThumbnailsGenerator
{
private TileFilter $tileFilter;
private int $durationInSeconds;
private Closure $sequenceFilenameResolver;
public function __construct(TileFilter $tileFilter, int $durationInSeconds, Closure $sequenceFilenameResolver)
{
$this->tileFilter = $tileFilter;
$this->durationInSeconds = $durationInSeconds;
$this->sequenceFilenameResolver = $sequenceFilenameResolver;
}
/**
* Returns the x,y,w,h position of the given thumb key.
*
* @param integer $thumbKey
* @return string
*/
private function getPositionOnTile(int $thumbKey): string
{
$row = (int) floor($thumbKey / $this->tileFilter->columns);
$column = ($thumbKey - ($row * $this->tileFilter->columns)) % $this->tileFilter->columns;
$dimension = $this->tileFilter->getCalculatedDimension();
$width = $dimension->getWidth();
$height = $dimension->getHeight();
// base position
$x = $column * $width;
$y = $row * $height;
// add margin
$x += $this->tileFilter->margin;
$y += $this->tileFilter->margin;
// add padding
$x += $this->tileFilter->padding * $column;
$y += $this->tileFilter->padding * $row;
return implode(',', [$x, $y, $width, $height]);
}
/**
* Returns the formatted timestamp of the given thumb key.
*
* @param integer $thumbKey
* @return string
*/
private function getTimestamp(int $thumbKey): string
{
return sprintf(
'%02d:%02d:%02d.000',
($thumbKey * $this->tileFilter->interval) / 3600,
($thumbKey * $this->tileFilter->interval) / 60 % 60,
($thumbKey * $this->tileFilter->interval) % 60
);
}
/**
* Generates the WebVTT contents.
*
* @return string
*/
public function getContents(): string
{
$thumbsPerTile = $this->tileFilter->rows * $this->tileFilter->columns;
$totalFiles = ceil(
($this->durationInSeconds / $this->tileFilter->interval) / $thumbsPerTile
);
return Collection::range(1, $totalFiles * $thumbsPerTile)
->map(function ($thumb) use ($thumbsPerTile) {
$start = $this->getTimestamp($thumb - 1, $this->tileFilter->interval);
$end = $this->getTimestamp($thumb, $this->tileFilter->interval);
$fileKey = ceil($thumb / $thumbsPerTile);
$filename = sprintf(
call_user_func($this->sequenceFilenameResolver, $fileKey),
$fileKey
);
$positionOnTile = ($thumb - 1) % $thumbsPerTile;
$position = $this->getPositionOnTile($positionOnTile);
return implode(PHP_EOL, [
"{$start} --> {$end}",
"{$filename}#xywh={$position}",
]);
})
->prepend("WEBVTT")
->implode(PHP_EOL . PHP_EOL);
}
}