Saturday, April 25, 2015

Convert .MP4 to .AVI - Linux

$ sudo apt-get install mencoder

$ mencoder source_movie.mp4 -channels 6 -ovc xvid -xvidencopts fixed_quant=4 -vf harddup -oac pcm -o dest_movie.avi

Wednesday, April 8, 2015

simple python http server - BaseHTTPServer vs apache

http://stackoverflow.com/questions/5693741/whats-difference-between-a-simple-webserver-and-apache-server

Question

What's difference between a simple webserver and Apache server?

Answer @ ninjagecko
Or in other words, if i want to use python to implement a server which can be put into use of business, what also should i do?
There are already python-based web servers, such as CherryPy (which I think is intended to be a web server solution on the same stack level as Apache; it is more python-based though, and Apache has been around a lot longer).

If you wish to write a lightweight extremely simple webserver from scratch, there is probably nothing wrong with using BaseHTTPServer, other than perhaps a few outstanding design issues (I hear race conditions might permanently clog a socket until a thread dies).

Though I would not recommend it (alone) for business, some of the big boys use BaseHTTPServer with a bit of extra machinery: http://www.cherrypy.org/browser/trunk/cherrypy/_cphttpserver.py?rev=583

To elaborate, Apache is the industry standard. It has a plethora of configuration options, a security team, vulnerability mailing lists I think, etc. It supports modules (e.g. mod_python). Python-based web servers also support python-based modules (maybe they might allow you access to non-python things) via something called a WSGI stack; a WSGI application can run on any python-based web server (and Apache too, which also has a modwsgi); I think they are narrower in scope than Apache modules.

Apache module examples: http://httpd.apache.org/docs/2.0/mod/
WSGI examples (not a valid comparison): http://wsgi.org/wsgi/Middleware_and_Utilities

I might code my own webserver if I'm doing something extremely lightweight, or if I needed massive control over webserver internals that the module interfaces could not provide, or if I was doing a personal project. I would not code my own server for a business unless I had significant experience with how real-world web servers worked. This is especially important from a security vulnerability point-of-view.

For example, I once wrote a web-based music player. I used a BaseHTTPServer to serve music out of a sandbox I had written to ensure that people couldn't access arbitrary files. Threading was a nightmare. (I recall a bug where you needed to pass special arguments to Popen since threading caused an implicit fork which would cause hangs on dangling file descriptors.) There were other various issues. The code needed to be refactored a lot. It can be very worthwhile for a personal project, but is a significant undertaking and not worth it for a business that just needs a website.

I know two startups who have been content using Pylons (using Paste) or Turbogears (using CherryPy) in the past, if you're looking for a lightweight python web server stack. Their default template systems are lacking though. The choice between Apache and a leaner more python-based web server may also depend on the skillset of your co-developers.