diff --git a/lib/private/preview.php b/lib/private/preview.php
index c9d8810be6..6547d5b325 100644
--- a/lib/private/preview.php
+++ b/lib/private/preview.php
@@ -21,7 +21,7 @@ require_once 'preview/movie.php';
 require_once 'preview/mp3.php';
 require_once 'preview/svg.php';
 require_once 'preview/txt.php';
-require_once 'preview/office.php';
+require_once 'preview/office-cl.php';
 require_once 'preview/bitmap.php';
 
 class Preview {
@@ -744,10 +744,11 @@ class Preview {
 			return;
 		}
 
-		if (count(self::$providers) > 0) {
+		if (!empty(self::$providers)) {
 			return;
 		}
 
+		self::registerCoreProviders();
 		foreach (self::$registeredProviders as $provider) {
 			$class = $provider['class'];
 			$options = $provider['options'];
@@ -759,7 +760,74 @@ class Preview {
 
 		$keys = array_map('strlen', array_keys(self::$providers));
 		array_multisort($keys, SORT_DESC, self::$providers);
+	}
 
+	protected static function registerCoreProviders() {
+		self::registerProvider('OC\Preview\TXT');
+		self::registerProvider('OC\Preview\MarkDown');
+		self::registerProvider('OC\Preview\Image');
+		self::registerProvider('OC\Preview\MP3');
+
+		// SVG, Office and Bitmap require imagick
+		if (extension_loaded('imagick')) {
+			$checkImagick = new \Imagick();
+
+			$imagickProviders = array(
+				'SVG'	=> 'OC\Preview\SVG',
+				'TIFF'	=> 'OC\Preview\TIFF',
+				'PDF'	=> 'OC\Preview\PDF',
+				'AI'	=> 'OC\Preview\Illustrator',
+				'PSD'	=> 'OC\Preview\Photoshop',
+				// Requires adding 'eps' => array('application/postscript', null), to lib/private/mimetypes.list.php
+				'EPS'	=> 'OC\Preview\Postscript',
+			);
+
+			foreach ($imagickProviders as $queryFormat => $provider) {
+				if (count($checkImagick->queryFormats($queryFormat)) === 1) {
+					self::registerProvider($provider);
+				}
+			}
+
+			if (count($checkImagick->queryFormats('PDF')) === 1) {
+				// Office previews are currently not supported on Windows
+				if (!\OC_Util::runningOnWindows() && \OC_Helper::is_function_enabled('shell_exec')) {
+					$officeFound = is_string(\OC::$server->getConfig()->getSystemValue('preview_libreoffice_path', null));
+
+					if (!$officeFound) {
+						//let's see if there is libreoffice or openoffice on this machine
+						$whichLibreOffice = shell_exec('command -v libreoffice');
+						$officeFound = !empty($whichLibreOffice);
+						if (!$officeFound) {
+							$whichOpenOffice = shell_exec('command -v openoffice');
+							$officeFound = !empty($whichOpenOffice);
+						}
+					}
+
+					if ($officeFound) {
+						self::registerProvider('OC\Preview\MSOfficeDoc');
+						self::registerProvider('OC\Preview\MSOffice2003');
+						self::registerProvider('OC\Preview\MSOffice2007');
+						self::registerProvider('OC\Preview\OpenDocument');
+						self::registerProvider('OC\Preview\StarOffice');
+					}
+				}
+			}
+		}
+
+		// Video requires avconv or ffmpeg and is therefor
+		// currently not supported on Windows.
+		if (!\OC_Util::runningOnWindows()) {
+			$avconvBinary = \OC_Helper::findBinaryPath('avconv');
+			$ffmpegBinary = ($avconvBinary) ? null : \OC_Helper::findBinaryPath('ffmpeg');
+
+			if ($avconvBinary || $ffmpegBinary) {
+				// FIXME // a bit hacky but didn't want to use subclasses
+				\OC\Preview\Movie::$avconvBinary = $avconvBinary;
+				\OC\Preview\Movie::$ffmpegBinary = $ffmpegBinary;
+
+				self::registerProvider('OC\Preview\Movie');
+			}
+		}
 	}
 
 	/**
diff --git a/lib/private/preview/bitmap.php b/lib/private/preview/bitmap.php
index 748a63a6af..4632285348 100644
--- a/lib/private/preview/bitmap.php
+++ b/lib/private/preview/bitmap.php
@@ -9,10 +9,6 @@ namespace OC\Preview;
 
 use Imagick;
 
-if (extension_loaded('imagick')) {
-
-	$checkImagick = new Imagick();
-
 	class Bitmap extends Provider {
 
 		public function getMimeType() {
@@ -23,11 +19,11 @@ if (extension_loaded('imagick')) {
 			$tmpPath = $fileview->toTmpFile($path);
 
 			//create imagick object from bitmap or vector file
-			try{
+			try {
 				// Layer 0 contains either the bitmap or
 				// a flat representation of all vector layers
 				$bp = new Imagick($tmpPath . '[0]');
-				
+
 				$bp->setImageFormat('png');
 			} catch (\Exception $e) {
 				\OC_Log::write('core', $e->getmessage(), \OC_Log::ERROR);
@@ -35,17 +31,14 @@ if (extension_loaded('imagick')) {
 			}
 
 			unlink($tmpPath);
-			
+
 			//new bitmap image object
 			$image = new \OC_Image($bp);
 			//check if image object is valid
 			return $image->valid() ? $image : false;
 		}
-
 	}
-	
-	if(count($checkImagick->queryFormats('PDF')) === 1) {
-	
+
 		//.pdf
 		class PDF extends Bitmap {
 
@@ -54,12 +47,7 @@ if (extension_loaded('imagick')) {
 			}
 
 		}
-		
-		\OC\Preview::registerProvider('OC\Preview\PDF');
-	}
-	
-	if(count($checkImagick->queryFormats('TIFF')) === 1) {
-	
+
 		//.tiff
 		class TIFF extends Bitmap {
 
@@ -68,12 +56,7 @@ if (extension_loaded('imagick')) {
 			}
 
 		}
-		
-		\OC\Preview::registerProvider('OC\Preview\TIFF');
-	}
 
-	if(count($checkImagick->queryFormats('AI')) === 1) {
-	
 		//.ai
 		class Illustrator extends Bitmap {
 
@@ -82,12 +65,6 @@ if (extension_loaded('imagick')) {
 			}
 
 		}
-		
-		\OC\Preview::registerProvider('OC\Preview\Illustrator');
-	}
-	
-	// Requires adding 'eps' => array('application/postscript', null), to lib/private/mimetypes.list.php
-	if(count($checkImagick->queryFormats('EPS')) === 1) {
 
 		//.eps
 		class Postscript extends Bitmap {
@@ -98,11 +75,6 @@ if (extension_loaded('imagick')) {
 
 		}
 
-		\OC\Preview::registerProvider('OC\Preview\Postscript');
-	}
-	
-	if(count($checkImagick->queryFormats('PSD')) === 1) {
-	
 		//.psd
 		class Photoshop extends Bitmap {
 
@@ -111,7 +83,3 @@ if (extension_loaded('imagick')) {
 			}
 
 		}
-		
-		\OC\Preview::registerProvider('OC\Preview\Photoshop');
-	}
-}
diff --git a/lib/private/preview/image.php b/lib/private/preview/image.php
index 7bcbddc649..511052caf2 100644
--- a/lib/private/preview/image.php
+++ b/lib/private/preview/image.php
@@ -35,5 +35,3 @@ class Image extends Provider {
 	}
 
 }
-
-\OC\Preview::registerProvider('OC\Preview\Image');
diff --git a/lib/private/preview/movie.php b/lib/private/preview/movie.php
index d69266ceb3..850027c1a6 100644
--- a/lib/private/preview/movie.php
+++ b/lib/private/preview/movie.php
@@ -8,13 +8,6 @@
  */
 namespace OC\Preview;
 
-// movie preview is currently not supported on Windows
-if (!\OC_Util::runningOnWindows()) {
-	$avconvBinary = \OC_Helper::findBinaryPath('avconv');
-	$ffmpegBinary = ($avconvBinary) ? null : \OC_Helper::findBinaryPath('ffmpeg');
-
-	if ($avconvBinary || $ffmpegBinary) {
-
 		class Movie extends Provider {
 			public static $avconvBinary;
 			public static $ffmpegBinary;
@@ -95,12 +88,3 @@ if (!\OC_Util::runningOnWindows()) {
 				return false;
 			}
 		}
-
-		// a bit hacky but didn't want to use subclasses
-		Movie::$avconvBinary = $avconvBinary;
-		Movie::$ffmpegBinary = $ffmpegBinary;
-
-		\OC\Preview::registerProvider('OC\Preview\Movie');
-	}
-}
-
diff --git a/lib/private/preview/mp3.php b/lib/private/preview/mp3.php
index bb4d3dfce8..661cb92bf6 100644
--- a/lib/private/preview/mp3.php
+++ b/lib/private/preview/mp3.php
@@ -44,5 +44,3 @@ class MP3 extends Provider {
 	}
 
 }
-
-\OC\Preview::registerProvider('OC\Preview\MP3');
diff --git a/lib/private/preview/office-cl.php b/lib/private/preview/office-cl.php
index f5c791e37f..0f175e811d 100644
--- a/lib/private/preview/office-cl.php
+++ b/lib/private/preview/office-cl.php
@@ -7,9 +7,6 @@
  */
 namespace OC\Preview;
 
-// office preview is currently not supported on Windows
-if (!\OC_Util::runningOnWindows()) {
-
 	//we need imagick to convert
 	class Office extends Provider {
 
@@ -90,8 +87,6 @@ if (!\OC_Util::runningOnWindows()) {
 
 	}
 
-	\OC\Preview::registerProvider('OC\Preview\MSOfficeDoc');
-
 	//.docm, .dotm, .xls(m), .xlt(m), .xla(m), .ppt(m), .pot(m), .pps(m), .ppa(m)
 	class MSOffice2003 extends Office {
 
@@ -101,8 +96,6 @@ if (!\OC_Util::runningOnWindows()) {
 
 	}
 
-	\OC\Preview::registerProvider('OC\Preview\MSOffice2003');
-
 	//.docx, .dotx, .xlsx, .xltx, .pptx, .potx, .ppsx
 	class MSOffice2007 extends Office {
 
@@ -112,8 +105,6 @@ if (!\OC_Util::runningOnWindows()) {
 
 	}
 
-	\OC\Preview::registerProvider('OC\Preview\MSOffice2007');
-
 	//.odt, .ott, .oth, .odm, .odg, .otg, .odp, .otp, .ods, .ots, .odc, .odf, .odb, .odi, .oxt
 	class OpenDocument extends Office {
 
@@ -123,8 +114,6 @@ if (!\OC_Util::runningOnWindows()) {
 
 	}
 
-	\OC\Preview::registerProvider('OC\Preview\OpenDocument');
-
 	//.sxw, .stw, .sxc, .stc, .sxd, .std, .sxi, .sti, .sxg, .sxm
 	class StarOffice extends Office {
 
@@ -133,6 +122,3 @@ if (!\OC_Util::runningOnWindows()) {
 		}
 
 	}
-
-	\OC\Preview::registerProvider('OC\Preview\StarOffice');
-}
diff --git a/lib/private/preview/office.php b/lib/private/preview/office.php
deleted file mode 100644
index b47cbc6e08..0000000000
--- a/lib/private/preview/office.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-/**
- * Copyright (c) 2013 Georg Ehrke georg@ownCloud.com
- * This file is licensed under the Affero General Public License version 3 or
- * later.
- * See the COPYING-README file.
- */
-//both, libreoffice backend and php fallback, need imagick
-if (extension_loaded('imagick')) {
-
-	$checkImagick = new Imagick();
-
-	if(count($checkImagick->queryFormats('PDF')) === 1) {
-		$isShellExecEnabled = \OC_Helper::is_function_enabled('shell_exec');
-
-		// LibreOffice preview is currently not supported on Windows
-		if (!\OC_Util::runningOnWindows()) {
-			$whichLibreOffice = ($isShellExecEnabled ? shell_exec('command -v libreoffice') : '');
-			$isLibreOfficeAvailable = !empty($whichLibreOffice);
-			$whichOpenOffice = ($isShellExecEnabled ? shell_exec('command -v openoffice') : '');
-			$isOpenOfficeAvailable = !empty($whichOpenOffice);
-			//let's see if there is libreoffice or openoffice on this machine
-			if($isShellExecEnabled && ($isLibreOfficeAvailable || $isOpenOfficeAvailable || is_string(\OC_Config::getValue('preview_libreoffice_path', null)))) {
-				require_once('office-cl.php');
-			}
-		}
-	}
-}
diff --git a/lib/private/preview/provider.php b/lib/private/preview/provider.php
index f544c2c4b1..10e23efa20 100644
--- a/lib/private/preview/provider.php
+++ b/lib/private/preview/provider.php
@@ -5,18 +5,21 @@ abstract class Provider {
 	private $options;
 
 	public function __construct($options) {
-		$this->options=$options;
+		$this->options = $options;
 	}
 
+	/**
+	 * @return string Regex with the mimetypes that are supported by this provider
+	 */
 	abstract public function getMimeType();
 
 	/**
 	 * Check if a preview can be generated for $path
 	 *
-	 * @param string $path
+	 * @param \OC\Files\FileInfo $file
 	 * @return bool
 	 */
-	public function isAvailable($path) {
+	public function isAvailable($file) {
 		return true;
 	}
 
@@ -32,5 +35,4 @@ abstract class Provider {
 	 *		OC_Image object of the preview
 	 */
 	abstract public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview);
-
 }
diff --git a/lib/private/preview/svg.php b/lib/private/preview/svg.php
index 0b5dbc9716..6ddf893966 100644
--- a/lib/private/preview/svg.php
+++ b/lib/private/preview/svg.php
@@ -9,12 +9,6 @@ namespace OC\Preview;
 
 use Imagick;
 
-if (extension_loaded('imagick')) {
-
-	$checkImagick = new Imagick();
-
-	if(count($checkImagick->queryFormats('SVG')) === 1) {
-
 		class SVG extends Provider {
 
 			public function getMimeType() {
@@ -50,9 +44,4 @@ if (extension_loaded('imagick')) {
 				//check if image object is valid
 				return $image->valid() ? $image : false;
 			}
-
 		}
-
-		\OC\Preview::registerProvider('OC\Preview\SVG');
-	}
-}
diff --git a/lib/private/preview/txt.php b/lib/private/preview/txt.php
index 7f01b980c0..ff612e2509 100644
--- a/lib/private/preview/txt.php
+++ b/lib/private/preview/txt.php
@@ -8,28 +8,22 @@
 namespace OC\Preview;
 
 class TXT extends Provider {
-
+	/**
+	 * {@inheritDoc}
+	 */
 	public function getMimeType() {
 		return '/text\/plain/';
 	}
 
 	/**
-	 * Check if a preview can be generated for $path
-	 *
-	 * @param \OC\Files\FileInfo $file
-	 * @return bool
+	 * {@inheritDoc}
 	 */
 	public function isAvailable($file) {
 		return $file->getSize() > 5;
 	}
 
 	/**
-	 * @param string $path
-	 * @param int $maxX
-	 * @param int $maxY
-	 * @param boolean $scalingup
-	 * @param \OC\Files\View $fileview
-	 * @return bool|\OC_Image
+	 * {@inheritDoc}
 	 */
 	public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
 
@@ -80,14 +74,9 @@ class TXT extends Provider {
 	}
 }
 
-\OC\Preview::registerProvider('OC\Preview\TXT');
-
 class MarkDown extends TXT {
-
 	public function getMimeType() {
 		return '/text\/(x-)?markdown/';
 	}
 
 }
-
-\OC\Preview::registerProvider('OC\Preview\MarkDown');