Implement our own quicktime parser

app/Media/QuickTime/Atoms/moov/trak/tkhd.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace App\Media\QuickTime\Atoms\moov\trak;
+
+// An atom that specifies the characteristics of a single track within a movie
+
+use Illuminate\Support\Arr;
+
+use App\Media\QuickTime\Atoms\SubAtom;
+
+class tkhd extends SubAtom
+{
+	protected const unpack = [
+		'version'=>['c',1],
+		'flags'=>['a3',3],
+		'create'=>['N',4],
+		'modified'=>['N',4],
+		'trakid'=>['N',4],	// The value 0 cannot be used
+		'reserved1'=>['a4',4],
+		'duration'=>['N',4],
+		'reserved2'=>['a8',8],
+		'layer'=>['n',2],
+		'altgroup'=>['n',2],
+		'volume'=>['a2',2],	// 16 bit fixed point
+		'reserved3'=>['a2',2],
+		'matrix'=>['a36',36],
+		'twidth'=>['a4',4],	// 32 bit fixed point
+		'theight'=>['a4',4], // 32 bit fixed point
+	];
+
+	public function __construct(int $offset,int $size,string $filename,?string $data)
+	{
+		parent::__construct($offset,$size,$filename,$data);
+
+		$this->cache = $this->cache();
+
+		// For debugging
+		if (FALSE)
+			$this->debug = hex_dump($data ?: $this->data());
+	}
+
+	public function __get($key): mixed
+	{
+		switch ($key) {
+			case 'height':
+				return fixed_point_int_to_float(Arr::get($this->cache(),'theight'));
+
+			case 'width':
+				return fixed_point_int_to_float(Arr::get($this->cache(),'twidth'));
+
+			default:
+				return parent::__get($key);
+		}
+	}
+}