+
+    def _extract_cf_auth(self, webpage):
+        policy = self._search_regex(r'InfoQConstants\.scp\s*=\s*\'([^\']+)\'', webpage, 'policy')
+        signature = self._search_regex(r'InfoQConstants\.scs\s*=\s*\'([^\']+)\'', webpage, 'signature')
+        key_pair_id = self._search_regex(r'InfoQConstants\.sck\s*=\s*\'([^\']+)\'', webpage, 'key-pair-id')
+        return {
+            'Policy': policy,
+            'Signature': signature,
+            'Key-Pair-Id': key_pair_id,
+        }
+
+    def _extract_http_video(self, webpage):
+        http_video_url = self._search_regex(r'P\.s\s*=\s*\'([^\']+)\'', webpage, 'video URL')
+        http_video_url = update_url_query(http_video_url, self._extract_cf_auth(webpage))
+        return [{
+            'format_id': 'http_video',
+            'url': http_video_url,
+        }]
+
+    def _extract_http_audio(self, webpage, video_id):
+        fields = self._hidden_inputs(webpage)
+        http_audio_url = fields.get('filename')
+        if not http_audio_url:
+            return []
+
+        # base URL is found in the Location header in the response returned by
+        # GET https://www.infoq.com/mp3download.action?filename=... when logged in.
+        http_audio_url = compat_urlparse.urljoin('http://res.infoq.com/downloads/mp3downloads/', http_audio_url)
+        http_audio_url = update_url_query(http_audio_url, self._extract_cf_auth(webpage))
+
+        # audio file seem to be missing some times even if there is a download link
+        # so probe URL to make sure
+        if not self._is_valid_url(http_audio_url, video_id):
+            return []
+
+        return [{
+            'format_id': 'http_audio',
+            'url': http_audio_url,
+            'vcodec': 'none',
+        }]
+
+    def _real_extract(self, url):
+        video_id = self._match_id(url)
+        webpage = self._download_webpage(url, video_id)
+
+        video_title = self._html_search_regex(r'<title>(.*?)</title>', webpage, 'title')
+        video_description = self._html_search_meta('description', webpage, 'description')
+
+        if '/cn/' in url:
+            # for China videos, HTTP video URL exists but always fails with 403
+            formats = self._extract_bokecc_formats(webpage, video_id)
+        else:
+            formats = (
+                self._extract_rtmp_video(webpage)
+                + self._extract_http_video(webpage)
+                + self._extract_http_audio(webpage, video_id))
+