From d8f81e41871b0638ecf15de4cc14b426ab98381a Mon Sep 17 00:00:00 2001
From: John-Mark Gurney <jmg@funkthat.com>
Date: Mon, 25 Feb 2008 01:41:36 -0800
Subject: [PATCH] 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 | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/mpegtsmod.py b/mpegtsmod.py
index 3ef734b..042ba35 100644
--- a/mpegtsmod.py
+++ b/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)