diff -u b/core/modules/file/file.module b/core/modules/file/file.module
--- b/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -564,10 +564,10 @@
       'render element' => 'element',
     ),
     'file_audio' => array(
-      'variables' => array( 'files' => array(), 'attributes' => NULL),
+      'variables' => array('files' => array(), 'attributes' => NULL),
     ),
     'file_video' => array(
-      'variables' => array( 'files' => array(), 'attributes' => NULL),
+      'variables' => array('files' => array(), 'attributes' => NULL),
     ),
 
     // From file.field.inc.
diff -u b/core/modules/file/src/Plugin/Field/FieldFormatter/FileAudioFormatter.php b/core/modules/file/src/Plugin/Field/FieldFormatter/FileAudioFormatter.php
--- b/core/modules/file/src/Plugin/Field/FieldFormatter/FileAudioFormatter.php
+++ b/core/modules/file/src/Plugin/Field/FieldFormatter/FileAudioFormatter.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- *  Contains Drupal\file\Plugin\Field\FieldFormatter\FileAudioFormatter
- */
-
 namespace Drupal\file\Plugin\Field\FieldFormatter;
 
 
@@ -32,14 +27,17 @@
 class FileAudioFormatter extends FileMediaFormatter implements ContainerFactoryPluginInterface {
 
   /**
+   * {@inheritdoc}
+   */
+  const APPLICABLE_MIME_TYPE = 'audio';
+
+  /**
    * The renderer service.
    *
    * @var \Drupal\Core\Render\RendererInterface
    */
   protected $renderer;
 
-  const applicableMimeType = 'audio';
-
   /**
    * Constructs a FileAudioFormatter instance.
    *
@@ -57,10 +55,8 @@
    *   The view mode.
    * @param array $third_party_settings
    *   Any third party settings settings.
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
-   *   The entity manager.
-   * @param Drupal\Core\Render\RendererInterface $renderer
-   *   The rendered service
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The rendered service.
    */
   public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, $label, $view_mode, array $third_party_settings, RendererInterface $renderer) {
     parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $label, $view_mode, $third_party_settings);
@@ -87,12 +83,12 @@
    * {@inheritdoc}
    */
   public static function defaultSettings() {
-    return array(
+    return [
       'controls' => TRUE,
       'autoplay' => FALSE,
       'loop' => FALSE,
       'multiple_file_behavior' => 'tags',
-    ) + parent::defaultSettings();
+    ] + parent::defaultSettings();
   }
 
   /**
@@ -131,7 +127,7 @@
    * {@inheritdoc}
    */
   public function settingsSummary() {
-    $summary = array();
+    $summary = [];
     $summary[] = t('Controls: %controls', array('%controls' => $this->getSetting('controls') ? 'visible' : 'hidden'));
     $summary[] = t('Autoplay: %autoplay', array('%autoplay' => $this->getSetting('autoplay') ? t('yes') : t('no')));
     $summary[] = t('Loop: %loop', array('%loop' => $this->getSetting('loop') ? t('yes') : t('no')));
@@ -143,15 +139,11 @@
    * {@inheritdoc}
    */
   public function viewElements(FieldItemListInterface $items, $langcode) {
-    $elements = array();
+    $elements = [];
     $multiple_file_behavior = $this->getSetting('multiple_file_behavior');
-    $source_files = array();
+    $source_files = [];
     // Because we can have the files grouped in a single audio tag, we do a
     // grouping in case the multiple file behavior is not 'tags'.
-    /**
-     * @var integer $delta
-     * @var File $file
-     */
     foreach ($this->getEntitiesToView($items, $langcode) as $delta => $file) {
       $mimeTypeType = static::getMimeTypeType($file->getMimeType());
 
diff -u b/core/modules/file/src/Plugin/Field/FieldFormatter/FileMediaFormatter.php b/core/modules/file/src/Plugin/Field/FieldFormatter/FileMediaFormatter.php
--- b/core/modules/file/src/Plugin/Field/FieldFormatter/FileMediaFormatter.php
+++ b/core/modules/file/src/Plugin/Field/FieldFormatter/FileMediaFormatter.php
@@ -1,8 +1,4 @@
 <?php
-/**
- * @file
- * Contains
- */
 
 namespace Drupal\file\Plugin\Field\FieldFormatter;
 
@@ -10,9 +6,15 @@
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Symfony\Component\HttpFoundation\File\MimeType\MimeTypeGuesserInterface;
 
+/**
+ * Base class for media file formatter.
+ */
 abstract class FileMediaFormatter extends FileFormatterBase {
 
-  const applicableMimeType = FALSE;
+  /**
+   * The applicable mimetype for a formatter.
+   */
+  const APPLICABLE_MIME_TYPE = FALSE;
 
   /**
    * {@inheritdoc}
@@ -29,7 +31,7 @@
 
       $mimeType = $extensionMimeTypeGuesser->guess('fakedFile.' . $extension);
 
-      if (static::getMimeTypeType($mimeType) == static::applicableMimeType) {
+      if (static::getMimeTypeType($mimeType) == static::APPLICABLE_MIME_TYPE) {
         $applicable = TRUE;
       }
     }
@@ -43,8 +45,12 @@
+   * @param string $mimeType
+   *   The full mimeType.
+   *
    * @return string
-   *   The mimetype.
+   *   The last part of a mimetype.
    */
   public static function getMimeTypeType($mimeType) {
     list($type, $subtype) = explode('/', $mimeType, 2);
     return $type;
   }
-}
\ No newline at end of file
+
+}
diff -u b/core/modules/file/src/Plugin/Field/FieldFormatter/FileVideoFormatter.php b/core/modules/file/src/Plugin/Field/FieldFormatter/FileVideoFormatter.php
--- b/core/modules/file/src/Plugin/Field/FieldFormatter/FileVideoFormatter.php
+++ b/core/modules/file/src/Plugin/Field/FieldFormatter/FileVideoFormatter.php
@@ -1,10 +1,5 @@
 <?php
 
-/**
- * @file
- *  Contains Drupal\file\Plugin\Field\FieldFormatter\FileVideoFormatter.
- */
-
 namespace Drupal\file\Plugin\Field\FieldFormatter;
 
 
@@ -31,7 +26,10 @@
  */
 class FileVideoFormatter extends FileMediaFormatter implements ContainerFactoryPluginInterface {
 
-  const applicableMimeType = 'video';
+  /**
+   * {@inheritdoc}
+   */
+  const APPLICABLE_MIME_TYPE = 'video';
 
   /**
    * The renderer service.
@@ -57,10 +55,8 @@
    *   The view mode.
    * @param array $third_party_settings
    *   Any third party settings settings.
-   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
-   *   The entity manager.
-   * @param Drupal\Core\Render\RendererInterface $renderer
-   *   The rendered service
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The rendered service.
    */
   public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, $label, $view_mode, array $third_party_settings, RendererInterface $renderer) {
     parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $label, $view_mode, $third_party_settings);
@@ -166,7 +162,7 @@
     if ($width && $height) {
       $summary[] = t('Size: %width x %height pixels', array(
         '%width' => $this->getSetting('width'),
-        '%height' => $this->getSetting('height')
+        '%height' => $this->getSetting('height'),
       ));
     }
     $summary[] = t('Multiple files: %multiple', array('%multiple' => $this->getSetting('multiple_file_behavior')));
@@ -182,11 +178,6 @@
     $source_files = array();
     // Because we can have the files grouped in a single video tag, we do a
     // grouping in case the multiple file behavior is not 'tags'.
-
-    /**
-     * @var integer $delta
-     * @var FileInterface $file
-     */
     foreach ($this->getEntitiesToView($items, $langcode) as $delta => $file) {
       $mimeTypeType = static::getMimeTypeType($file->getMimeType());
       if ($mimeTypeType == 'video') {
@@ -233 +224,2 @@
-}
\ No newline at end of file
+
+}
diff -u b/core/modules/file/tests/src/Kernel/Formatter/FileAudioFormatterTest.php b/core/modules/file/tests/src/Kernel/Formatter/FileAudioFormatterTest.php
--- b/core/modules/file/tests/src/Kernel/Formatter/FileAudioFormatterTest.php
+++ b/core/modules/file/tests/src/Kernel/Formatter/FileAudioFormatterTest.php
@@ -18,21 +18,29 @@
 class FileAudioFormatterTest extends KernelTestBase {
 
   /**
+   * The entity type.
+   *
    * @var string
    */
   protected $entityType;
 
   /**
+   * The bundle type.
+   *
    * @var string
    */
   protected $bundle;
 
   /**
+   * The field name.
+   *
    * @var string
    */
   protected $fieldName;
 
   /**
+   * The view display.
+   *
    * @var \Drupal\Core\Entity\Display\EntityViewDisplayInterface
    */
   protected $display;
@@ -86,8 +94,7 @@
     ]);
     $this->display->setComponent($this->fieldName, [
       'type' => 'file_audio',
-      'settings' => [
-      ],
+      'settings' => [],
     ]);
     $this->display->save();
 
@@ -103,12 +110,14 @@
       'uri' => 'public://file.mp3',
       'filename' => 'file.mp3',
     ]);
-    $file-> save();
+    $file->save();
 
     $entity = EntityTest::create([
-      $this->fieldName => [[
-        'target_id' => $file->id(),
-      ],],
+      $this->fieldName => [
+        [
+          'target_id' => $file->id(),
+        ],
+      ],
     ]);
     $entity->save();
 
@@ -136 +145 @@
-}
\ No newline at end of file
+}
diff -u b/core/modules/file/tests/src/Kernel/Formatter/FileVideoFormatterTest.php b/core/modules/file/tests/src/Kernel/Formatter/FileVideoFormatterTest.php
--- b/core/modules/file/tests/src/Kernel/Formatter/FileVideoFormatterTest.php
+++ b/core/modules/file/tests/src/Kernel/Formatter/FileVideoFormatterTest.php
@@ -18,21 +18,29 @@
 class FileVideoFormatterTest extends KernelTestBase {
 
   /**
+   * The entity type.
+   *
    * @var string
    */
   protected $entityType;
 
   /**
+   * The bundle type.
+   *
    * @var string
    */
   protected $bundle;
 
   /**
+   * The field name.
+   *
    * @var string
    */
   protected $fieldName;
 
   /**
+   * The view display.
+   *
    * @var \Drupal\Core\Entity\Display\EntityViewDisplayInterface
    */
   protected $display;
@@ -86,8 +94,7 @@
     ]);
     $this->display->setComponent($this->fieldName, [
       'type' => 'file_video',
-      'settings' => [
-      ],
+      'settings' => [],
     ]);
     $this->display->save();
 
@@ -103,12 +110,14 @@
       'uri' => 'public://file.mp4',
       'filename' => 'file.mp4',
     ]);
-    $file-> save();
+    $file->save();
 
     $entity = EntityTest::create([
-      $this->fieldName => [[
-        'target_id' => $file->id(),
-      ],],
+      $this->fieldName => [
+        [
+          'target_id' => $file->id(),
+        ],
+      ],
     ]);
     $entity->save();
 
@@ -136 +145 @@
-}
\ No newline at end of file
+}