make it cheaper to have the mpegtsmod loaded... We now do a quick

check to make sure there are TS packets, before scanning the first
2megs in an expensive iter loop to find out that there are none...
this makes things a lot faster...

[git-p4: depot-paths = "//depot/": change = 1126]

mpegtsmod.py

@@ -344,7 +344,27 @@ class MultiMPEGTS(FSObject, StorageFolder):
 		if doupdate:
 			StorageFolder.doUpdate(self)
 
+def findtsstream(fp, pktsz=188):
+	d = fp.read(200*pktsz)
+	i = 5
+	pos = 0
+	while i and pos < len(d) and pos != -1:
+		if d[pos] == 'G':
+			i -= 1
+			pos += pktsz
+		else:
+			i = 5
+			pos = d.find('G', pos + 1)
+
+	if i or pos == -1:
+		return False
+
+	return True
+
 def detectmpegts(path, fobj):
+	if not findtsstream(fobj):
+		return None, None
+
 	f = mpegts.TSPStream(_LimitedFile(path, size= 2*1024*1024))
 	tvct = mpegts.GetTVCT(f)