Input mp3 file returns 0 - php

Question

When I try to input an mp3 file the $_FILES returns null.
Controller:
$audio = $_FILES['muziek']['tmp_name'];
if ($audio != ''){
$audioContent = file_get_contents($audio);
$this->load->model('muziek_model');
$this->muziek_model->insertMuziek($audioContent);
}
var_dump($audio);
var_dump($audioContent);
View:
<?php echo form_open_multipart('Muziek/uploadMuziek');?>
<table>
<tr>
<td><?php echo form_label('MP3 Bestand:', 'muziek'); ?></td>
<td><input type="file" name="muziek" id="muziek" accept=".mp3" style="margin-left: 10px; padding-bottom: 35px; color: black" class="btn btn-login form-control login-formcontrol bg-white"/></td>
</tr>
<tr>
<td></td>
<td>
<?php echo form_submit('knop', 'Uploaden', 'class = "btn btn-login login-formcontrol"'); ?>
</td>
</tr>
</table>
<?php echo form_close();?>
When I select an mp3 file audio should not be null

Answer 1

File uploads can fail for a variety of reasons. https://www.php.net/manual/en/features.file-upload.errors.php
Your's is failing because it is too big:
Value: 1; The uploaded file exceeds the upload_max_filesize directive
in php.ini.
If you have access to php.ini you can change this variable to make it accept larger files.
Even if you do this with success, I would suggest checking for upload errors if(!isset($_FILES['muziek']['tmp_name']) || $_FILES['muziek']['error'] !== 0) { echo 'error'; } before trying to perform actions on a file that may or may not exist.
I personally use: https://github.com/verot/class.upload.php
but Codeigniter has an in-built upload library.