diff --git a/inc/lib/webm/ffmpeg.php b/inc/lib/webm/ffmpeg.php
index f9a50cf7..f62bfced 100644
--- a/inc/lib/webm/ffmpeg.php
+++ b/inc/lib/webm/ffmpeg.php
@@ -13,35 +13,92 @@ function get_webm_info($filename) {
 
 	exec("$ffprobe -v quiet -print_format json -show_format -show_streams $filename", $ffprobe_out);
 	$ffprobe_out = json_decode(implode("\n", $ffprobe_out), 1);
-	$webminfo['error'] = is_valid_webm($ffprobe_out);
+	$validcheck = is_valid_webm($ffprobe_out);
+	$webminfo['error'] = $validcheck['error'];
 	if(empty($webminfo['error'])) {
-		$webminfo['width'] = $ffprobe_out['streams'][0]['width'];
-		$webminfo['height'] = $ffprobe_out['streams'][0]['height'];
+		$trackmap = $validcheck['trackmap'];
+		$videoidx = $trackmap['videoat'][0];
+		$webminfo['width'] = $ffprobe_out['streams'][$videoidx]['width'];
+		$webminfo['height'] = $ffprobe_out['streams'][$videoidx]['height'];
 		$webminfo['duration'] = $ffprobe_out['format']['duration'];
 	}
 	return $webminfo;
 }
+
+function locate_webm_tracks($ffprobe_out) {
+    $streams     = $ffprobe_out['streams'];
+    $streamcount = count($streams);
+    $videoat     = array();
+    $audioat     = array();
+    $others      = array();
+
+    for ($k = 0; $k < $streamcount; $k++) {
+        $stream     = $streams[$k];
+        $codec_type = $stream['codec_type'];
+
+        if ($codec_type === 'video') {
+            $videoat[] = $k;
+        } elseif($codec_type === 'audio') {
+            $audioat[] = $k;
+        } else {
+            if (isset($others[$codec_type])) {
+                $others[$codec_type][] = $k;
+            } else {
+                $others[$codec_type] = [$k];
+            }
+        }
+    }
+
+    return array('videoat' => $videoat, 'audioat' => $audioat, 'others' => $others);
+/*
+var_dump example:
+array(3) {
+  ["videoat"]=>  array(1) {
+    [0]=>    int(0)
+  }
+  ["audioat"]=>  array(1) {
+    [0]=>    int(1)
+  }
+  ["others"]=>  array(1) {
+    ["data"]=>    array(2) {
+      [0]=>      int(2)
+      [1]=>      int(3)
+    }
+  }
+}
+ */
+}
+
 function is_valid_webm($ffprobe_out) {
 	global $board, $config;
 	if (empty($ffprobe_out))
-		return array('code' => 1, 'msg' => $config['error']['genwebmerror']);
+		return array('error' => array('code' => 1, 'msg' => $config['error']['genwebmerror']));
+	$trackmap = locate_webm_tracks($ffprobe_out);
+
+	// one video track
+	if (count($trackmap['videoat']) != 1)
+		return array('error' => array('code' => 2, 'msg' => $config['error']['invalidwebm']." [video track count]"));
+	$videoidx = $trackmap['videoat'][0];
+
 	$extension = pathinfo($ffprobe_out['format']['filename'], PATHINFO_EXTENSION);
 	if ($extension === 'webm' && !stristr($ffprobe_out['format']['format_name'], 'mp4')) {
 		if ($ffprobe_out['format']['format_name'] != 'matroska,webm')
-			return array('code' => 2, 'msg' => $config['error']['invalidwebm']."error 1");
+			return array('error' => array('code' => 2, 'msg' => $config['error']['invalidwebm']."error 1"));
 	} elseif ($extension === 'mp4' || stristr($ffprobe_out['format']['format_name'], 'mp4')) {
-		if ($ffprobe_out['streams'][0]['codec_name'] != 'h264' && $ffprobe_out['streams'][1]['codec_name'] != 'aac')
-			return array('code' => 2, 'msg' => $config['error']['invalidwebm']."error 2");
+		// if the video is not h264 or (there is audio but it's not aac)
+		if (($ffprobe_out['streams'][$videoidx]['codec_name'] != 'h264') || ((count($trackmap['audioat']) > 0) && ($ffprobe_out['streams'][$trackmap['audioat'][0]]['codec_name'] != 'aac')))
+			return array('error' => array('code' => 2, 'msg' => $config['error']['invalidwebm']." [h264/aac check]"));
 	} else {
-		return array('code' => 1, 'msg' => $config['error']['genwebmerror']."error 3");  
+		return array('error' => array('code' => 1, 'msg' => $config['error']['genwebmerror']."error 3"));
 	}
 	if ((count($ffprobe_out['streams']) > 1) && (!$config['webm']['allow_audio']))
-		return array('code' => 3, 'msg' => $config['error']['webmhasaudio']."error 4");
-	if ((empty($ffprobe_out['streams'][0]['width']) || (empty($ffprobe_out['streams'][0]['height']))) && !$config['webm']['allow_audio']) {
-		return array('code' => 2, 'msg' => $config['error']['invalidwebm']."error 5");
+		return array('error' => array('code' => 3, 'msg' => $config['error']['webmhasaudio']."error 4"));
+	if ((count($trackmap['audioat']) > 0) && !$config['webm']['allow_audio']) {
+		return array('error' => array('code' => 3, 'msg' => $config['error']['webmhasaudio']."error 5"));
 	}
 	if ($ffprobe_out['format']['duration'] > $config['webm']['max_length'])
-		return array('code' => 4, 'msg' => sprintf($config['error']['webmtoolong'], $config['webm']['max_length'])."error 6");
+		return array('error' => array('code' => 4, 'msg' => sprintf($config['error']['webmtoolong'], $config['webm']['max_length'])."error 6"));
+	return array('error' => array(), 'trackmap' => $trackmap);
 }
 function make_webm_thumbnail($filename, $thumbnail, $width, $height, $duration) {
 	global $board, $config;
@@ -65,4 +122,4 @@ function make_webm_thumbnail($filename, $thumbnail, $width, $height, $duration)
 		}
 	}
 	return $ret;
-}
+}
\ No newline at end of file