Madhav Kobal's Blog

This blog will be dedicated to Linux, Open Source and Technology news, affairs, how-tos and virtually EVERYTHING in these domains.

VLC 1.1.0 (Final) Has Been Released!

Posted by madhavkobal on 21/06/2010

Quietly, VLC 1.1.0 final (stable) was posted to the VLC git a few minutes ago. VLC 1.1.0 brings extensions support as well as GPU and DSP decoding among many other new features. Read on!

What’s new in VLC 1.1.0:

  • GPU and DSP decoding on selected platforms
  • New support for codecs, demuxers and muxers
  • Lua extensions and Lua content extensions (luaSD)
  • Improved interfaces
  • Video Output rework
  • Removal of lots of modules, rewrite of many
  • Improved performances, in CPU, RAM and I/O
  • New libVLC and bindings
  • New or improved ports on misc platforms
  • And many other features and bugs fixes

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Run your own Ubuntu Enterprise Cloud Guide

Posted by madhavkobal on 21/06/2010

Ubuntu Enterprise Cloud is the product, powered by Eucalyptus, that allows you to easily run your own Amazon-EC2-like private cloud. It’s a lot simpler than you’d think.
This is 3 parts tutorial you can use to Run your own Ubuntu Enterprise Cloud

Run your own Ubuntu Enterprise Cloud, part 1

Run your own Ubuntu Enterprise Cloud, part 2

Run your own Ubuntu Enterprise Cloud, part 3

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Element OS – Home Theatre OS

Posted by madhavkobal on 21/06/2010

Overview of Element

Bridging the divide between the internet and television…
Element is a free operating system for home theater PCs, media center computers, and set-top boxes. Featuring an innovative “across the room” interface designed to be connected to your HDTV for a digital media and internet experience from within the comforts of your own living room or lounge. Element comes loaded with the software needed to stream all forms of web content  and manage your own multimedia library and downloads.  We’ve included many popular open source applications, each adapted to our unique interface, such as the Firefox Web Browser, Pidgin Messenger, and XBMC Media Center, along with access to numerous on-line content services from Hulu, Cooliris, Boxee, Clicker, Amazon on Demand, Youtube XL, and more.

Our aim has been to design an environment that is simple and intuitive while not sacrificing aesthetics or the ability to customise your system. We’ve enhanced a traditional mouse/keyboard driven environment through our unique implementation of a ten-foot user interface, providing our users a streamlined multimedia and internet experience they can pick up the essentials of in minutes and enjoy from across the room on there HDTV. If you have an Android handset then you can conveniently use it as a remote or purchase any of the affordable handheld keyboard/trackpad remotes compatible with Element in our Hardware section.

Unlike similar home-theater systems (Roku, Popcorn, etc) that are based around a single media center app or framework, Element is a complete application platform. What this means is even though Element comes preloaded with XBMC for media management and Cooliris for streaming content, you can add any number of apps or services such as Boxee, Hulu Desktop, Moovida, and to name a few.  Our system isn’t just for running different types of media software either, Element provides a full fledged computing and internet experience with hundreds of applications available all morphed to fit in our ten-foot user interface, from web browsers, to word processors, movie editors, photo managers, and most anything else you can imagine. You could even use Element as a gaming console with many 3D and general games available. In total over 1500 applications and almost 500 games are currently installable with a single click through our partners AllMyApps Software Center and our own Addons/Extra section.

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YouTube Gains Online Editing Features

Posted by madhavkobal on 20/06/2010

Google recently announced a new feature found in YouTube’s TestLabs. The YouTube Video Editor is a trial feature that will allow YouTube video creators to edit their videos online without any additional software.

In its initial form, the video editor allows users to do the following: combine multiple videos to create a new longer video; trim the beginning and/or ending of videos; add soundtracks from YouTube’s AudioSwap library; and create new videos online with no uploading required.

There are definitely helpful features to have. I upload a lot of video to YouTube. Every now and then, a mistake makes its way into the final, posted video. In order to fix it, I have to delete or hide the existing video, edit it on my desktop, and re-upload the new version. While it’s mostly painless, there’s a big drawback: you lose all your views.

Since YouTube now allows for editing online, it might be possible to edit out mistakes without losing your page views.

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Visual File Diff with Vimdiff

Posted by madhavkobal on 19/06/2010

vimdiff utility gives a better visual feeling of differences between files as explained in this article.

1. Difference in whole line – Blue Color and Hyphens

If line X is available in one file and not available in another file, then file containing the line will be highlighted with blue color, and the file without that line will be displayed with hypens and in light green color as shown below.

Fig: Whole line difference in Vimdiff (click on image to enlarge)

2. Difference in partial line – Red Color

If only a part of the line is different between the two files, the line will be highlighted in rose color, and the partial difference will be highlighted with red color as shown below.

Fig: Partial line difference in Vimdiff (click on the image to enlarge)

3. Lines are same

If some lines of the two files are same, it will appear as it is ( i.e without any highlight ).

If many lines of the two files are same, it will be folded automatically, and shown as +N lines as shown below. To expand the fold press SPACE.

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Convert Linux man pages to PDF

Posted by madhavkobal on 19/06/2010

man is the system’s manual pager. Each page argument given to man is normally the name of a program,  utility  or  function. The manual page associated with each of these arguments is then found and displayed and these man pages are stored in some special format.

Now, suppose you need to convert these man pages to PDF files which are more readable and easy to print
Below simple command will convert any man pages to PDF file

man -t yast | ps2pdf – yast.pdf

Now you can view yast.pdf in your favorite PDF viewer.

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Editing PDFs in Linux

Posted by madhavkobal on 19/06/2010

It would be great if all PDF files could be easily manipulated without relying on bloated, proprietary, update-obsessive applications (I’m looking at you, Adobe).  But the fact that that’s not the case doesn’t mean Ubuntu users are out of luck when it comes to editing PDFs.  Here’s a look at some of the PDF editors available for Linux, and how well they work.

Short backstory: I recently found myself wanting to fill in some text fields in a PDF file that wasn’t designed to be editable.  Although Evince, Ubuntu’s built-in PDF reader, was able to open the file without a problem, it didn’t offer any functionality for adding or modifying text.  Neither did Acrobat Reader, which I also unfortunately have to have installed on my computer.

Not despairing, I fired up the Software Center to see what other applications were out there that might be able to do what I needed without making me resort to the command line.  Here’s an overview of what I found.


The first program I tried was the aptly named PDFedit.  It’s a Qt-based application, meaning that it required me to download a bunch of extra libraries, but it offers a wide range of functionality for modifying and adding both texts and graphics to a PDF file.  For my needs, which were limited to inserting text, it was adequate, although not ideal.

PDFedit screenshot

The add-text feature works well and supports a variety of different fonts, sizes and colors, but I found it difficult to specify exactly where I wanted to add the text.  The application also seemed buggy in that it froze for a few seconds every time I finished adding a new line of text.  And there was no undo feature, which would be nice to have.

For these reasons, it would be difficult to use PDFedit for inserting extensive lines of text to a document.  For other purposes, though, it’s a solid and relatively feature-rich application for modifying PDFs.


I found flpsed, a more obscure PDF editor, to be the application best suited to my particular needs.  Adding text is its only main feature, but it does it pretty well.  The arrow keys can be used to specify where exactly text should be entered, which was hugely helpful in keeping everything aligned.

flpsed screenshot

flpsed’s shortcomings include a lack of undo functionality, no way to specify the font of inserted text (only size and color can be changed) and no support for editing existing text in the imported file in any way.  Overall, the application is also very rough around the edges, with an interface reminiscent of 1999.  But for me, it got the job done with little hassle.


Another approach for editing PDFs, and the one on which I’ve traditionally relied in the past, is to use the GIMP.  Documents can be imported into GIMP and edited like any other image:

GIMP screenshot

The drawbacks to this strategy, however, are that edited files can’t be exported back to PDF–they can be saved only as images–and documents have to be imported page-by-page.  For my purposes, GIMP was far from ideal, but in other circumstances its ability to import PDF files can be very handy.


Sun offers a PDF Import Extension for OpenOffice, which I also tried out.  It was easy to install, but my PDF file was a little corrupted when I imported it into OpenOffice, with some parts of the text overlapping and others running off the page:

OpenOffice screenshot

The colliding text was disappointing, because otherwise this seems like it would have been a great way to do what I needed.  The extension developers do warn, however, that some documents work better than others; perhaps I was simply unlucky in having a document that didn’t agree with the importer.  And to the extension’s credit, I found that it was able to import other documents without issue, as shown below:

OpenOffice screenshot


The last application I tested was Xournal, which is designed primarily for notetaking on tablet computers and which supports annotating PDFs.  When it came to filling in text fields using the keyboard, Xournal was similar to PDFedit: I could easily select a font, size and color, but it was difficult to specify the exact position of the letters.  For light textual editing, Xournal would be useful, but it’s much better suited for annotating PDFs by hand with a stylus.

Xournal screenshot


In the end, I stuck with flpsed, which ended up working pretty well for my limited needs.  The most promising application that I encountered, however, was OpenOffice, which seems very capable of a variety of PDF-editing tasks as long as it’s able to import the file cleanly.

In the future, I’d love to see edit functionality incorporated into Evince so that Ubuntu would be able to modify PDF files out-of-the-box.  But I’ll be happy enough just to get the visa application that launched this blog post approved.

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Audio/Video/Image/Text/ISO Convert Nautilus Script

Posted by madhavkobal on 18/06/2010

Right-click on a file, and this script will decide what conversions are appropriate, ask some questions about what you want, and execute the proper command and options to convert it into something else.
Convert multimedia files from one format to another, change size if desired
Convert multimedia to audio-only files
Convert audio files from one format to another. Both multimedia and audio can specify numerous ffmpeg options
– these options are stored in user-configurable files, including one designed for user submissions
Convert images from one format to another, and/or change image resolution (and jpg compression)
Convert documents from one format to another
Convert text to a .jpg file (an image of your text) or a .wav file (a voice reading your text)
Convert multi-image files, like pdf or animated gif, into a series of frames
– pdf to gif creates animaged gif, animated gif to pdf creates multi-page pdf
Convert various “CD Image” files into standard .iso files
Batch processing to apply conversion choices to all selected files in a single operation
Originals are not overwritten. Generated files are named based on the source and conversion choices

Install Audio/Video/Image/Text/ISO Convert Nautilus Script in Ubuntu

Preparing your system

Open the terminal and run the following command

sudo aptitude install links elinks zenity

First you need to download this script from here and extract. Then do one or more of these with the file “avconvert”:

(1) move (or copy or link) it to ~/.gnome2/nautilus-scripts

(2) move (or copy or link) it to somewhere in $PATH (eg /usr/local/bin)

(3) do #2, then add it as a nautilus-action (set “paramater” to “%M”, check “multiple files”)

(4) add it to Gnome panel/launch-bar (drag/drop or right-click panel Add/Custom-Application)


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Using rdist to copy files to multiple hosts

Posted by madhavkobal on 18/06/2010

RDist is an open source program to maintain identical copies of files over multiple hosts. It preserves the owner, group, mode, and mtime of files if possible and can update programs that are executing.

Almost all versions of UNIX include RDist. However, most that do include a very old version sometimes referred to as “4.2BSD rdist”, “rdist classic”, or “rdist version 3”.

Major Features

This version of RDist does not need to be setuid “root” at all. Rdist now uses rsh(1c) (remote command) or ssh(1) program to make connections to remote hosts, instead of making the connection directly. This eliminates the need to be run as “root”. (Many thanks to Chris Siebenmann and John DiMarco who came up with an rsh version of rcmd() that makes this possible.)

One of the transports that can be used with RDist is SSH. When used with SSH (see the rdist(1) man page) RDist can perform secure and encrypted updates. If your SSH is compiled with SOCKS support, RDist can perform secure and encrypted updates through SOCKS compliant firewall systems.


View the INSTALL.html file which came with your distribution for instructions on how to build and install RDist.

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Convert a PDF file into a single Image using ImageMagick

Posted by madhavkobal on 18/06/2010

Don’t know when you might feel the necessity to convert a pdf into a .jpg or a .png file, but in case you have to, then ImageMagick will make this job really easy for you. ImageMagick is a great opensource command line utility for image manipulation.

Since, we are dealing with image conversion we will use the “convert” script, provided by ImageMagick.

[shredder12]$ convert file.pdf image.png

If the pdf file(file.pdf) has only one page then a single image.png file will be formed. In case of multiple pages, same number of image-[n].png files will be produced. For example, a three page pdf will result into three image files – image-0.png, image-1.png and image-2.png.

If you want to combine/stitch all these images together to form a single one, something similar to taking a snapshot of the whole pdf, then just run the following command.

[shredder12]$ convert image-* -append single_image.png

This will result in a single image file.

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