Merge pull request #251 from videojs/hlse-perf

Optimize decryption

@@ -637,6 +637,8 @@ videojs.Hls.prototype.loadSegment = function(segmentUri, offset) {
     responseType: 'arraybuffer',
     withCredentials: settings.withCredentials
   }, function(error, url) {
+    var segmentInfo;
+
     // the segment request is no longer outstanding
     tech.segmentXhr_ = null;
 
@@ -669,12 +671,26 @@ videojs.Hls.prototype.loadSegment = function(segmentUri, offset) {
     // if the segment is the start of a timestamp discontinuity,
     // we have to wait until the sourcebuffer is empty before
     // aborting the source buffer processing
-    tech.segmentBuffer_.push({
+    segmentInfo = {
+      // the segment's mediaIndex at the time it was received
       mediaIndex: tech.mediaIndex,
+      // the segment's playlist
       playlist: tech.playlists.media(),
+      // optionally, a time offset to seek to within the segment
       offset: offset,
-      bytes: new Uint8Array(this.response)
-    });
+      // unencrypted bytes of the segment
+      bytes: null,
+      // when a key is defined for this segment, the encrypted bytes
+      encryptedBytes: null,
+      // optionally, the decrypter that is unencrypting the segment
+      decrypter: null
+    };
+    if (segmentInfo.playlist.segments[segmentInfo.mediaIndex].key) {
+      segmentInfo.encryptedBytes = new Uint8Array(this.response);
+    } else {
+      segmentInfo.bytes = new Uint8Array(this.response);
+    }
+    tech.segmentBuffer_.push(segmentInfo);
     player.trigger('progress');
     tech.drainBuffer();
 
@@ -689,12 +705,15 @@ videojs.Hls.prototype.loadSegment = function(segmentUri, offset) {
 videojs.Hls.prototype.drainBuffer = function(event) {
   var
     i = 0,
+    segmentInfo,
     mediaIndex,
     playlist,
     offset,
     tags,
     bytes,
     segment,
+    decrypter,
+    segIv,
 
     ptsTime,
     segmentOffset,
@@ -704,28 +723,45 @@ videojs.Hls.prototype.drainBuffer = function(event) {
     return;
   }
 
-  mediaIndex = segmentBuffer[0].mediaIndex;
-  playlist = segmentBuffer[0].playlist;
-  offset = segmentBuffer[0].offset;
-  bytes = segmentBuffer[0].bytes;
+  segmentInfo = segmentBuffer[0];
+
+  mediaIndex = segmentInfo.mediaIndex;
+  playlist = segmentInfo.playlist;
+  offset = segmentInfo.offset;
+  bytes = segmentInfo.bytes;
   segment = playlist.segments[mediaIndex];
 
-  if (segment.key) {
+  if (segment.key && !bytes) {
+
     // this is an encrypted segment
     // if the key download failed, we want to skip this segment
     // but if the key hasn't downloaded yet, we want to try again later
     if (keyFailed(segment.key)) {
       return segmentBuffer.shift();
     } else if (!segment.key.bytes) {
+
       // trigger a key request if one is not already in-flight
       return this.fetchKeys_();
+
+    } else if (segmentInfo.decrypter) {
+
+      // decryption is in progress, try again later
+      return;
+
     } else {
       // if the media sequence is greater than 2^32, the IV will be incorrect
       // assuming 10s segments, that would be about 1300 years
-      var segIv = segment.key.iv || new Uint32Array([0, 0, 0, mediaIndex + playlist.mediaSequence]);
-      bytes = videojs.Hls.decrypt(bytes,
-                                  segment.key.bytes,
-                                  segIv);
+      segIv = segment.key.iv || new Uint32Array([0, 0, 0, mediaIndex + playlist.mediaSequence]);
+
+      // create a decrypter to incrementally decrypt the segment
+      decrypter = new videojs.Hls.Decrypter(segmentInfo.encryptedBytes,
+                                            segment.key.bytes,
+                                            segIv,
+                                            function(err, bytes) {
+                                              segmentInfo.bytes = bytes;
+                                            });
+      segmentInfo.decrypter = decrypter;
+      return;
     }
   }
 

-(function(window, videojs, undefined) {
+(function(window, videojs, unpad, undefined) {
   'use strict';
   /*
     ======== A Handy Little QUnit Reference ========
@@ -46,7 +46,7 @@ test('decrypts a single AES-128 with PKCS7 block', function() {
       0x82, 0xa8, 0xf0, 0x67]);
 
   deepEqual('howdy folks',
-            stringFromBytes(videojs.Hls.decrypt(encrypted, key, initVector)),
+            stringFromBytes(unpad(videojs.Hls.decrypt(encrypted, key, initVector))),
             'decrypted with a byte array key');
 });
 
@@ -68,8 +68,100 @@ test('decrypts multiple AES-128 blocks with CBC', function() {
     ]);
 
   deepEqual('0123456789abcdef01234',
-            stringFromBytes(videojs.Hls.decrypt(encrypted, key, initVector)),
+            stringFromBytes(unpad(videojs.Hls.decrypt(encrypted, key, initVector))),
             'decrypted multiple blocks');
 });
 
-})(window, window.videojs);
+var clock;
+
+module('Incremental Processing', {
+  setup: function() {
+    clock = sinon.useFakeTimers();
+  },
+  teardown: function() {
+    clock.restore();
+  }
+});
+
+test('executes a callback after a timeout', function() {
+  var asyncStream = new videojs.Hls.AsyncStream(),
+      calls = '';
+  asyncStream.push(function() {
+    calls += 'a';
+  });
+
+  clock.tick(asyncStream.delay);
+  equal(calls, 'a', 'invoked the callback once');
+  clock.tick(asyncStream.delay);
+  equal(calls, 'a', 'only invoked the callback once');
+});
+
+test('executes callback in series', function() {
+  var asyncStream = new videojs.Hls.AsyncStream(),
+      calls = '';
+  asyncStream.push(function() {
+    calls += 'a';
+  });
+  asyncStream.push(function() {
+    calls += 'b';
+  });
+
+  clock.tick(asyncStream.delay);
+  equal(calls, 'a', 'invoked the first callback');
+  clock.tick(asyncStream.delay);
+  equal(calls, 'ab', 'invoked the second');
+});
+
+var decrypter;
+
+module('Incremental Decryption', {
+  setup: function() {
+    clock = sinon.useFakeTimers();
+  },
+  teardown: function() {
+    clock.restore();
+  }
+});
+
+test('asynchronously decrypts a 4-word block', function() {
+  var
+    key =  new Uint32Array([0, 0, 0, 0]),
+    initVector = key,
+    // the string "howdy folks" encrypted
+    encrypted = new Uint8Array([
+      0xce, 0x90, 0x97, 0xd0,
+      0x08, 0x46, 0x4d, 0x18,
+      0x4f, 0xae, 0x01, 0x1c,
+      0x82, 0xa8, 0xf0, 0x67]),
+    decrypted;
+
+  decrypter = new videojs.Hls.Decrypter(encrypted, key, initVector, function(error, result) {
+    decrypted = result;
+  });
+  ok(!decrypted, 'asynchronously decrypts');
+
+  clock.tick(decrypter.asyncStream_.delay * 2);
+
+  ok(decrypted, 'completed decryption');
+  deepEqual('howdy folks',
+            stringFromBytes(decrypted),
+            'decrypts and unpads the result');
+});
+
+test('breaks up input greater than the step value', function() {
+  var encrypted = new Int32Array(videojs.Hls.Decrypter.STEP + 4),
+      done = false,
+      decrypter = new videojs.Hls.Decrypter(encrypted,
+                                            new Uint32Array(4),
+                                            new Uint32Array(4),
+                                            function() {
+                                              done = true;
+                                            });
+  clock.tick(decrypter.asyncStream_.delay * 2);
+  ok(!done, 'not finished after two ticks');
+
+  clock.tick(decrypter.asyncStream_.delay);
+  ok(done, 'finished after the last chunk is decrypted');
+});
+
+})(window, window.videojs, window.pkcs7.unpad);

@@ -152,10 +152,8 @@ module('HLS', {
 
     oldNativeHlsSupport = videojs.Hls.supportsNativeHls;
 
-    oldDecrypt = videojs.Hls.decrypt;
-    videojs.Hls.decrypt = function() {
-      return new Uint8Array([0]);
-    };
+    oldDecrypt = videojs.Hls.Decrypter;
+    videojs.Hls.Decrypter = function() {};
 
     // fake XHRs
     xhr = sinon.useFakeXMLHttpRequest();
@@ -173,7 +171,7 @@ module('HLS', {
     videojs.MediaSource.open = oldMediaSourceOpen;
     videojs.Hls.SegmentParser = oldSegmentParser;
     videojs.Hls.supportsNativeHls = oldNativeHlsSupport;
-    videojs.Hls.decrypt = oldDecrypt;
+    videojs.Hls.Decrypter = oldDecrypt;
     videojs.SourceBuffer = oldSourceBuffer;
     window.setTimeout = oldSetTimeout;
     window.clearTimeout = oldClearTimeout;
@@ -1904,6 +1902,10 @@ test('a new key XHR is created when a the segment is received', function() {
                            '#EXT-X-ENDLIST\n');
   standardXHRResponse(requests.shift()); // segment 1
   standardXHRResponse(requests.shift()); // key 1
+  // "finish" decrypting segment 1
+  player.hls.segmentBuffer_[0].bytes = new Uint8Array(16);
+  player.hls.checkBuffer_();
+
   standardXHRResponse(requests.shift()); // segment 2
 
   strictEqual(requests.length, 1, 'a key XHR is created');
@@ -2009,6 +2011,9 @@ test('skip segments if key requests fail more than once', function() {
   // key for second segment
   requests[0].response = new Uint32Array([0,0,0,0]).buffer;
   requests.shift().respond(200, null, '');
+  // "finish" decryption
+  player.hls.segmentBuffer_[0].bytes = new Uint8Array(16);
+  player.hls.checkBuffer_();
 
   equal(bytes.length, 2, 'bytes from the second ts segment should be added');
   equal(bytes[1], 1, 'the bytes from the second segment are added and not the first');
@@ -2033,9 +2038,8 @@ test('the key is supplied to the decrypter in the correct format', function() {
                          'http://media.example.com/fileSequence52-B.ts\n');
 
 
-  videojs.Hls.decrypt = function(bytes, key) {
+  videojs.Hls.Decrypter = function(encrypted, key) {
     keys.push(key);
-    return new Uint8Array([0]);
   };
 
   standardXHRResponse(requests.shift()); // segment
@@ -2043,7 +2047,7 @@ test('the key is supplied to the decrypter in the correct format', function() {
   requests[0].respond(200, null, '');
   requests.shift(); // key
 
-  equal(keys.length, 1, 'only one call to decrypt was made');
+  equal(keys.length, 1, 'only one Decrypter was constructed');
   deepEqual(keys[0],
             new Uint32Array([0, 0x01000000, 0x02000000, 0x03000000]),
             'passed the specified segment key');
@@ -2068,9 +2072,8 @@ test('supplies the media sequence of current segment as the IV by default, if no
                          'http://media.example.com/fileSequence52-B.ts\n');
 
 
-  videojs.Hls.decrypt = function(bytes, key, iv) {
+  videojs.Hls.Decrypter = function(encrypted, key, iv) {
     ivs.push(iv);
-    return new Uint8Array([0]);
   };
 
   requests[0].response = new Uint32Array([0,0,0,0]).buffer;
@@ -2078,7 +2081,7 @@ test('supplies the media sequence of current segment as the IV by default, if no
   requests.shift();
   standardXHRResponse(requests.pop());
 
-  equal(ivs.length, 1, 'only one call to decrypt was made');
+  equal(ivs.length, 1, 'only one Decrypter was constructed');
   deepEqual(ivs[0],
         new Uint32Array([0, 0, 0, 5]),
         'the IV for the segment is the media sequence');