diff --git a/actions/apimediaupload.php b/actions/apimediaupload.php
index fd1ff565c7..8a63706822 100644
--- a/actions/apimediaupload.php
+++ b/actions/apimediaupload.php
@@ -57,6 +57,11 @@ class ApiMediaUploadAction extends ApiAuthAction
     {
         parent::handle();
 
+        // fallback to xml for older clients etc
+        if (empty($this->format)) {
+            $this->format = 'xml';
+        }
+
         // Workaround for PHP returning empty $_POST and $_FILES when POST
         // length > post_max_size in php.ini
 
@@ -69,7 +74,7 @@ class ApiMediaUploadAction extends ApiAuthAction
             $msg = _m('The server was unable to handle that much POST data (%s byte) due to its current configuration.',
                       'The server was unable to handle that much POST data (%s bytes) due to its current configuration.',
                       intval($_SERVER['CONTENT_LENGTH']));
-            $this->clientError(sprintf($msg, $_SERVER['CONTENT_LENGTH']));
+            throw new ClientException(sprintf($msg, $_SERVER['CONTENT_LENGTH']));
         }
 
         // we could catch "NoUploadedMediaException" as "no media uploaded", but here we _always_ want an upload
@@ -77,6 +82,9 @@ class ApiMediaUploadAction extends ApiAuthAction
         
         // Thumbnails will be generated/cached on demand when accessed (such as with /attachment/:id/thumbnail)
 
+        if (!in_array($this->format, ['json', 'xml'])) {
+            throw new ClientException('This API call does not support the format '._ve($this->format));
+        }
         $this->showResponse($upload);
     }
 
@@ -88,19 +96,61 @@ class ApiMediaUploadAction extends ApiAuthAction
      *
      * @return void
      */
-    function showResponse(MediaFile $upload)
+    protected function showResponse(MediaFile $upload)
+    {
+        $this->initDocument($this->format);
+        switch ($this->format) {
+        case 'json':
+            return $this->showResponseJson($upload);
+        case 'xml':
+            return $this->showResponseXml($upload);
+        default:
+            throw new ClientException('This API call does not support the format '._ve($this->format));
+        }
+        $this->endDocument($this->format);
+    }
+
+    protected function showResponseJson(MediaFile $upload)
+    {
+        $enc = $upload->fileRecord->getEnclosure();
+
+        // note that we use media_id instead of mediaid which XML users might've gotten used to (nowadays we service media_id in both!)
+        $output = [
+                'media_id' => $upload->fileRecord->id,
+                'media_id_string' => (string)$upload->fileRecord->id,
+                'media_url' => $upload->shortUrl(),
+                'size' => $upload->fileRecord->size,
+                ];
+        if (common_get_mime_media($enc->mimetype) === 'image') {
+            $output['image'] = [
+                                'w' => $enc->width,
+                                'h' => $enc->height,
+                                'image_type' => $enc->mimetype,
+                                ];
+        }
+        print json_encode($output);
+    }
+
+    protected function showResponseXml(MediaFile $upload)
     {
-        $this->initDocument();
         $this->elementStart('rsp', array('stat' => 'ok', 'xmlns:atom'=>Activity::ATOM));
         $this->element('mediaid', null, $upload->fileRecord->id);
         $this->element('mediaurl', null, $upload->shortUrl());
+        $this->element('media_url', null, $upload->shortUrl());
+        $this->element('size', null, $upload->fileRecord->size);
 
         $enclosure = $upload->fileRecord->getEnclosure();
         $this->element('atom:link', array('rel'  => 'enclosure',
                                           'href' => $enclosure->url,
                                           'type' => $enclosure->mimetype));
+
+        // Twitter specific metadata expected in response since Twitter's Media upload API v1.1 (even though Twitter doesn't use XML)
+        $this->element('media_id', null, $upload->fileRecord->id);
+        $this->element('media_id_string', null, (string)$upload->fileRecord->id);
+        if (common_get_mime_media($enclosure->mimetype) === 'image') {
+            $this->element('image', ['w'=>$enclosure->width, 'h'=>$enclosure->height, 'image_type'=>$enclosure->mimetype]);
+        }
         $this->elementEnd('rsp');
-        $this->endDocument();
     }
 
     /**
@@ -110,15 +160,24 @@ class ApiMediaUploadAction extends ApiAuthAction
      */
     function clientError($msg, $code=400, $format=null)
     {
-        $this->initDocument();
-        $this->elementStart('rsp', array('stat' => 'fail'));
+        $this->initDocument($this->format);
+        switch ($this->format) {
+        case 'json':
+            $error = ['errors' => array()];
+            $error['errors'][] = ['message'=>$msg, 'code'=>131];
+            print json_encode($error);
+            break;
+        case 'xml':
+            $this->elementStart('rsp', array('stat' => 'fail'));
 
-        // @todo add in error code
-        $errAttr = array('msg' => $msg);
+            // @todo add in error code
+            $errAttr = array('msg' => $msg);
 
-        $this->element('err', $errAttr, null);
-        $this->elementEnd('rsp');
-        $this->endDocument();
+            $this->element('err', $errAttr, null);
+            $this->elementEnd('rsp');
+            break;
+        }
+        $this->endDocument($this->format);
         exit;
     }
 }
diff --git a/classes/File.php b/classes/File.php
index beb1f8f324..776db48985 100644
--- a/classes/File.php
+++ b/classes/File.php
@@ -369,8 +369,10 @@ class File extends Managed_DataObject
         }
 
         $enclosure = (object) array();
-        foreach (array('title', 'url', 'date', 'modified', 'size', 'mimetype') as $key) {
-            $enclosure->$key = $this->$key;
+        foreach (array('title', 'url', 'date', 'modified', 'size', 'mimetype', 'width', 'height') as $key) {
+            if ($this->$key !== '') {
+                $enclosure->$key = $this->$key;
+            }
         }
 
         $needMoreMetadataMimetypes = array(null, 'application/xhtml+xml', 'text/html');
diff --git a/lib/router.php b/lib/router.php
index a339585434..f66d928bcd 100644
--- a/lib/router.php
+++ b/lib/router.php
@@ -764,6 +764,13 @@ class Router
                 'api/statuses/update_with_media.json',
                 array('action' => 'ApiMediaUpload')
             );
+            // Twitter Media upload API v1.1
+            $m->connect(
+                'api/media/upload.:format',
+                array('action' => 'ApiMediaUpload',
+                      'format' => '(xml|json)',
+                      )
+            );
 
             // search
             $m->connect('api/search.atom', array('action' => 'ApiSearchAtom'));
diff --git a/plugins/Oembed/OembedPlugin.php b/plugins/Oembed/OembedPlugin.php
index 4adf6d35c1..23ee6148ea 100644
--- a/plugins/Oembed/OembedPlugin.php
+++ b/plugins/Oembed/OembedPlugin.php
@@ -179,8 +179,8 @@ class OembedPlugin extends Plugin
             return true;
         }
 
-        foreach (array('mimetype', 'url', 'title', 'modified') as $key) {
-            if (!empty($oembed->{$key})) {
+        foreach (array('mimetype', 'url', 'title', 'modified', 'width', 'height') as $key) {
+            if (isset($oembed->{$key}) && !empty($oembed->{$key})) {
                 $enclosure->{$key} = $oembed->{$key};
             }
         }