From: James Bunton <jamesbunton@delx.net.au>
Date: Fri, 2 Aug 2013 14:27:17 +0000 (+1000)
Subject: support for decoding YouTube's new video signature stuff
X-Git-Url: https://code.delx.au/youtube-cgi/commitdiff_plain/c8c1dd3e28a11753a9e49b6c377a0e332180b77d?ds=sidebyside

support for decoding YouTube's new video signature stuff
---

diff --git a/youtube.cgi b/youtube.cgi
index 2d3fcee..263259c 100755
--- a/youtube.cgi
+++ b/youtube.cgi
@@ -145,18 +145,39 @@ def get_player_config(doc):
 					convert_from_old_itag(player_config)
 					return player_config
 
+def decode_signature(js_url, s):
+	script = urlopen(js_url).read()
+	func_name = re.search(R"\b([a-z]+)\([a-z]+\.s\);", script).groups()[0]
+	p1 = script.find("function " + func_name)
+	p2 = script.find("}", p1)
+	func_block = script[p1:p2+1]
+
+	p = subprocess.Popen(
+		["js"],
+		stdin=subprocess.PIPE,
+		stdout=subprocess.PIPE
+	)
+	p.stdin.write(func_block + "\n")
+	p.stdin.write("console.log(%s('%s'));\n" % (func_name, s))
+	p.stdin.close()
+
+	signature = p.stdout.read().strip()
+	if p.wait() != 0:
+		raise Exception("js failed to execute: %d" % p.returncode)
+
+	return signature
+
 def get_best_video(player_config):
 	url_data_list = player_config["args"]["url_encoded_fmt_stream_map"].split(",")
+	js_url = player_config["assets"]["js"]
 
 	best_url = None
 	best_quality = None
 	best_extension = None
 	for url_data in url_data_list:
 		url_data = urlparse.parse_qs(url_data)
-		video_url = url_data["url"][0]
 		mimetype = url_data["type"][0].split(";")[0]
 		quality = url_data["quality"][0]
-		signature = url_data["sig"][0]
 
 		if quality not in QUALITIES:
 			continue
@@ -165,12 +186,20 @@ def get_best_video(player_config):
 
 		extension = MIMETYPES[mimetype]
 		quality = QUALITIES.get(quality, -1)
+
+		if best_quality is not None and quality < best_quality:
+			continue
+
+		video_url = url_data["url"][0]
+		if "sig" in url_data:
+			signature = url_data["sig"][0]
+		else:
+			signature = decode_signature(js_url, url_data["s"][0])
 		video_url = append_to_qs(video_url, {"signature": signature})
 
-		if best_quality is None or quality > best_quality:
-			best_url = video_url
-			best_quality = quality
-			best_extension = extension
+		best_url = video_url
+		best_quality = quality
+		best_extension = extension
 
 	return best_url, best_extension
 
@@ -327,7 +356,7 @@ def main():
 
 
 if __name__ == "__main__":
-	resource.setrlimit(resource.RLIMIT_AS, (MAX_MEMORY_BYTES, MAX_MEMORY_BYTES))
+###	resource.setrlimit(resource.RLIMIT_AS, (MAX_MEMORY_BYTES, MAX_MEMORY_BYTES))
 	if os.environ.has_key("SCRIPT_NAME"):
 		cgimain()
 	else: