diff --git a/src/Code/Converters/TtmlConverter.php b/src/Code/Converters/TtmlConverter.php
index 7f3acb1..190100a 100644
--- a/src/Code/Converters/TtmlConverter.php
+++ b/src/Code/Converters/TtmlConverter.php
@@ -75,14 +75,25 @@ public function fileContentToInternalFormat($file_content)
     public function internalFormatToFileContent(array $internal_format)
     {
         $file_content = '<?xml version="1.0" encoding="utf-8"?>
-<tt xmlns="http://www.w3.org/ns/ttml" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/ns/ttml#style" xml:lang="en" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
+<tt xmlns="http://www.w3.org/ns/ttml" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/ns/ttml#styling" xml:lang="en" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
   <head>
     <metadata>
       <ttm:title></ttm:title>
     </metadata>
     <styling>
-      <style id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16" tts:fontFamily="sansSerif" tts:color="white" />
+      <style xml:id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16px" tts:fontFamily="sansSerif" tts:color="white" />
     </styling>
+    <layout>
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="start" xml:id="topLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="start" xml:id="centerLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="start" xml:id="bottomLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="center" xml:id="topCenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="center" xml:id="centerСenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="center" xml:id="bottomCenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="end" xml:id="topRight" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="end" xml:id="centerRight" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="end" xml:id="bottomRight" />
+    </layout>
   </head>
   <body style="s0">
     <div>
@@ -93,7 +104,7 @@ public function internalFormatToFileContent(array $internal_format)
             $end = static::internalTimeToTtml($block['end']);
             $lines = implode("<br />", $block['lines']);
 
-            $file_content .= "      <p begin=\"{$start}s\" id=\"p{$k}\" end=\"{$end}s\">{$lines}</p>\n";
+            $file_content .= "      <p begin=\"{$start}s\" xml:id=\"p{$k}\" end=\"{$end}s\">{$lines}</p>\n";
         }
 
         $file_content .= '    </div>
@@ -132,7 +143,7 @@ public static function ttmlTimeToInternal($ttml_time, $frame_rate = null)
 
     protected static function internalTimeToTtml($internal_time)
     {
-        return number_format($internal_time, 1, '.', '');
+        return round($internal_time, 3);
     }
 
     protected static function framesPerSecond($dom)
diff --git a/tests/files/ttml.ttml b/tests/files/ttml.ttml
index 1c790ec..aa9984b 100644
--- a/tests/files/ttml.ttml
+++ b/tests/files/ttml.ttml
@@ -1,17 +1,28 @@
 <?xml version="1.0" encoding="utf-8"?>
-<tt xmlns="http://www.w3.org/ns/ttml" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/ns/ttml#style" xml:lang="en" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
+<tt xmlns="http://www.w3.org/ns/ttml" xmlns:ttp="http://www.w3.org/ns/ttml#parameter" ttp:timeBase="media" xmlns:tts="http://www.w3.org/ns/ttml#styling" xml:lang="en" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
   <head>
     <metadata>
       <ttm:title></ttm:title>
     </metadata>
     <styling>
-      <style id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16" tts:fontFamily="sansSerif" tts:color="white" />
+      <style xml:id="s0" tts:backgroundColor="black" tts:fontStyle="normal" tts:fontSize="16px" tts:fontFamily="sansSerif" tts:color="white" />
     </styling>
+    <layout>
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="start" xml:id="topLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="start" xml:id="centerLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="start" xml:id="bottomLeft" />
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="center" xml:id="topCenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="center" xml:id="centerСenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="center" xml:id="bottomCenter" />
+      <region tts:extent="80% 40%" tts:origin="10% 10%" tts:displayAlign="before" tts:textAlign="end" xml:id="topRight" />
+      <region tts:extent="80% 40%" tts:origin="10% 30%" tts:displayAlign="center" tts:textAlign="end" xml:id="centerRight" />
+      <region tts:extent="80% 40%" tts:origin="10% 50%" tts:displayAlign="after" tts:textAlign="end" xml:id="bottomRight" />
+    </layout>
   </head>
   <body style="s0">
     <div>
-      <p begin="137.4s" id="p0" end="140.4s">Senator, we're making<br />our final approach into Coruscant.</p>
-      <p begin="3740.5s" id="p1" end="3742.5s">Very good, Lieutenant.</p>
+      <p begin="137.4s" xml:id="p0" end="140.4s">Senator, we're making<br />our final approach into Coruscant.</p>
+      <p begin="3740.5s" xml:id="p1" end="3742.5s">Very good, Lieutenant.</p>
     </div>
   </body>
 </tt>
\ No newline at end of file
diff --git a/tests/formats/TtmlTest.php b/tests/formats/TtmlTest.php
index 7f3ccc8..765c48b 100644
--- a/tests/formats/TtmlTest.php
+++ b/tests/formats/TtmlTest.php
@@ -85,6 +85,13 @@ public function testTimeParseWithFpsAndMultiplierGiven()
         $this->assertInternalFormatsEqual($expected, $actual);
     }
 
+    public function testOutputsAccurateTimestamp()
+    {
+        $actual = (new Subtitles())->add(0.3, 8.456, 'test')->content('ttml');
+        $this->assertStringContainsString('"0.3s"', $actual);
+        $this->assertStringContainsString('"8.456s"', $actual);
+    }
+
     /**
      * @dataProvider timeFormatProvider
      */
