diff --git a/lib/vtt.js b/lib/vtt.js
index 66ab23f..6b7c56a 100644
--- a/lib/vtt.js
+++ b/lib/vtt.js
@@ -204,15 +204,18 @@
     }
   }
 
-  function parseCue(input, cue, regionList) {
+  function parseCue(input, cue, regionList, successCb, errCb) {
     // Remember the original input if we need to throw an error.
     var oInput = input;
     // 4.1 WebVTT timestamp
     function consumeTimeStamp() {
       var ts = parseTimeStamp(input);
       if (ts === null) {
-        throw new ParsingError(ParsingError.Errors.BadTimeStamp,
-                              "Malformed timestamp: " + oInput);
+        if (errCb) {
+          errCb(new ParsingError(ParsingError.Errors.BadTimeStamp,
+                                "Malformed timestamp: " + oInput));
+          return;
+        }
       }
       // Remove time stamp from input.
       input = input.replace(/^[^\sa-zA-Z-]+/, "");
@@ -270,15 +273,18 @@
       cue.lineAlign = settings.get("lineAlign", "start");
       cue.snapToLines = settings.get("snapToLines", true);
       cue.size = settings.get("size", 100);
-      cue.align = settings.get("align", "middle");
+      cue.align = settings.get("align", "center");
       cue.position = settings.get("position", "auto");
       cue.positionAlign = settings.get("positionAlign", {
         start: "start",
         left: "start",
         middle: "middle",
         end: "end",
-        right: "end"
+        right: "end",
+        center: "center"
       }, cue.align);
+
+      successCb();
     }
 
     function skipWhitespace() {
@@ -287,16 +293,23 @@
 
     // 4.1 WebVTT cue timings.
     skipWhitespace();
-    cue.startTime = consumeTimeStamp();   // (1) collect cue start time
+
+    var timestamp = consumeTimeStamp()
+    if (timestamp === undefined) return
+    cue.startTime = timestamp; // (1) collect cue start time
     skipWhitespace();
-    if (input.substr(0, 3) !== "-->") {     // (3) next characters must match "-->"
-      throw new ParsingError(ParsingError.Errors.BadTimeStamp,
+    if (input.substr(0, 3) !== "-->") {
+      // (3) next characters must match "-->"
+      errCb(new ParsingError(ParsingError.Errors.BadTimeStamp,
                              "Malformed time stamp (time stamps must be separated by '-->'): " +
-                             oInput);
+                             oInput));
+      return;
     }
     input = input.substr(3);
     skipWhitespace();
-    cue.endTime = consumeTimeStamp();     // (5) collect cue end time
+    var timestamp = consumeTimeStamp()
+    if (timestamp === undefined) return
+    cue.endTime = timestamp; // (5) collect cue end time
 
     // 4.1 WebVTT cue settings list.
     skipWhitespace();
@@ -1076,12 +1089,13 @@
     })();
   };
 
-  WebVTT.Parser = function(window, decoder) {
+  WebVTT.Parser = function(window, decoder, VTTCue) {
     this.window = window;
     this.state = "INITIAL";
     this.buffer = "";
     this.decoder = decoder || new TextDecoder("utf8");
     this.regionList = [];
+    this.VTTCue = VTTCue
   };
 
   WebVTT.Parser.prototype = {
@@ -1183,51 +1197,104 @@
         }
       }
 
-      // 3.2 WebVTT metadata header syntax
-      function parseHeader(input) {
-        parseOptions(input, function (k, v) {
+      // draft-pantos-http-live-streaming-20
+      // https://tools.ietf.org/html/draft-pantos-http-live-streaming-20#section-3.5
+      // 3.5 WebVTT
+      function parseTimestampMap(input) {
+        var settings = new Settings();
+
+        parseOptions(input, function(k, v) {
           switch (k) {
-          case "Region":
-            // 3.3 WebVTT region metadata header syntax
-            parseRegion(v);
-            break;
+            case "MPEGT":
+              settings.integer(k + 'S', v);
+              break;
+            case "LOCA":
+              settings.set(k + 'L', parseTimeStamp(v));
+              break;
           }
-        }, /:/);
+        }, /[^\d]:/, /,/);
+
+        self.ontimestampmap && self.ontimestampmap({
+          "MPEGTS": settings.get("MPEGTS"),
+          "LOCAL": settings.get("LOCAL")
+        });
+      }
+
+      // 3.2 WebVTT metadata header syntax
+      function parseHeader(input) {
+        if (input.match(/X-TIMESTAMP-MAP/)) {
+          // This line contains HLS X-TIMESTAMP-MAP metadata
+          parseOptions(input, function(k, v) {
+            switch (k) {
+              case "X-TIMESTAMP-MAP":
+                parseTimestampMap(v);
+                break;
+            }
+          }, /=/);
+        } else {
+          parseOptions(input, function (k, v) {
+            switch (k) {
+              case "Region":
+                // 3.3 WebVTT region metadata header syntax
+                parseRegion(v);
+                break;
+            }
+          }, /:/);
+        }
       }
 
       // 5.1 WebVTT file parsing.
-      try {
-        var line;
-        if (self.state === "INITIAL") {
-          // We can't start parsing until we have the first line.
-          if (!/\r\n|\n/.test(self.buffer)) {
-            return this;
-          }
 
-          line = collectNextLine();
+      function fail(e) {
 
-          var m = line.match(/^WEBVTT([ \t].*)?$/);
-          if (!m || !m[0]) {
-            throw new ParsingError(ParsingError.Errors.BadSignature);
-          }
+        self.reportOrThrowError(e);
 
-          self.state = "HEADER";
+        // If we are currently parsing a cue, report what we have.
+        if (self.state === "CUETEXT" && self.cue && self.oncue) {
+          self.oncue(self.cue);
         }
+        self.cue = null;
+        // Enter BADWEBVTT state if header was not parsed correctly otherwise
+        // another exception occurred so enter BADCUE state.
+        self.state = self.state === "INITIAL" ? "BADWEBVTT" : "BADCUE";
 
-        var alreadyCollectedLine = false;
-        while (self.buffer) {
-          // We can't parse a line until we have the full line.
-          if (!/\r\n|\n/.test(self.buffer)) {
-            return this;
-          }
+      }
 
-          if (!alreadyCollectedLine) {
-            line = collectNextLine();
-          } else {
-            alreadyCollectedLine = false;
-          }
+      var line;
+
+      if (self.state === "INITIAL") {
+        // We can't start parsing until we have the first line.
+        if (!/\r\n|\n/.test(self.buffer)) {
+          return this;
+        }
+
+        line = collectNextLine();
+
+        var m = line.match(/^WEBVTT([ \t].*)?$/);
+        if (!m || !m[0]) {
+            fail(new ParsingError(ParsingError.Errors.BadSignature))
+            return
+        }
 
-          switch (self.state) {
+        self.state = "HEADER";
+      }
+
+      var alreadyCollectedLine = false;
+
+      var lineparse = function() {
+        // We can't parse a line until we have the full line.
+        if (!self.buffer || !/\r\n|\n/.test(self.buffer)) {
+          self.flush()
+          return
+        }
+
+        if (!alreadyCollectedLine) {
+          line = collectNextLine();
+        } else {
+          alreadyCollectedLine = false;
+        }
+
+        switch (self.state) {
           case "HEADER":
             // 13-18 - Allow a header (metadata) under the WEBVTT line.
             if (/:/.test(line)) {
@@ -1236,45 +1303,59 @@
               // An empty line terminates the header and starts the body (cues).
               self.state = "ID";
             }
-            continue;
+            linebyline();
+            break;
           case "NOTE":
             // Ignore NOTE blocks.
             if (!line) {
               self.state = "ID";
             }
-            continue;
+            linebyline();
+            break;
           case "ID":
             // Check for the start of NOTE blocks.
             if (/^NOTE($|[ \t])/.test(line)) {
               self.state = "NOTE";
+              linebyline();
               break;
             }
             // 19-29 - Allow any number of line terminators, then initialize new cue values.
             if (!line) {
-              continue;
+              linebyline();
+              break;
             }
-            self.cue = new self.window.VTTCue(0, 0, "");
+            self.cue = new (self.VTTCue || self.window.VTTCue)(0, 0, "");
             self.state = "CUE";
             // 30-39 - Check if self line contains an optional identifier or timing data.
             if (line.indexOf("-->") === -1) {
               self.cue.id = line;
-              continue;
+              linebyline();
+              break;
             }
-            // Process line as start of a cue.
-            /*falls through*/
+          // Process line as start of a cue.
+          /*falls through*/
           case "CUE":
             // 40 - Collect cue timings and settings.
-            try {
-              parseCue(line, self.cue, self.regionList);
-            } catch (e) {
-              self.reportOrThrowError(e);
+
+            parseCue(line, self.cue, self.regionList, function successCb() {
+
+              self.state = "CUETEXT";
+
+              linebyline();
+
+            }, function errCb(err) {
+
+              self.reportOrThrowError(err);
+
               // In case of an error ignore rest of the cue.
               self.cue = null;
               self.state = "BADCUE";
-              continue;
-            }
-            self.state = "CUETEXT";
-            continue;
+
+              linebyline();
+
+            });
+
+            break;
           case "CUETEXT":
             var hasSubstring = line.indexOf("-->") !== -1;
             // 34 - If we have an empty line then report the cue.
@@ -1286,33 +1367,45 @@
               self.oncue && self.oncue(self.cue);
               self.cue = null;
               self.state = "ID";
-              continue;
-            }
+              linebyline();
+              break;
+          }
             if (self.cue.text) {
               self.cue.text += "\n";
             }
             self.cue.text += line;
-            continue;
-          case "BADCUE": // BADCUE
+            linebyline();
+            break;
+          case "BADCUE":
+            // BADCUE
             // 54-62 - Collect and discard the remaining cue.
             if (!line) {
               self.state = "ID";
             }
-            continue;
-          }
+            linebyline();
+            break;
         }
-      } catch (e) {
-        self.reportOrThrowError(e);
+      };
 
-        // If we are currently parsing a cue, report what we have.
-        if (self.state === "CUETEXT" && self.cue && self.oncue) {
-          self.oncue(self.cue);
+      var STACK_LIMIT = 1000;
+
+      var count = 0
+
+      function unwrapStack(fn) {
+        return function() {
+          count++
+          if (count < STACK_LIMIT) return fn()
+          setTimeout(function() {
+            count = 0
+            fn()
+          })
         }
-        self.cue = null;
-        // Enter BADWEBVTT state if header was not parsed correctly otherwise
-        // another exception occurred so enter BADCUE state.
-        self.state = self.state === "INITIAL" ? "BADWEBVTT" : "BADCUE";
       }
+
+      var linebyline = unwrapStack(lineparse)
+
+      linebyline();
+
       return this;
     },
     flush: function () {