Convert Midi to MP3 in Ubuntu

To convert a Midi File to Mp3 in Ubuntu, the easiest method I found (on ubuntuforums) uses the power of timidity:

 

sudo apt-get install timidity

to convert to mp3 either use ffmpeg

timidity My_midi_file.mid -Ow -o - | ffmpeg -i - -acodec libmp3lame -ab 64k my_converted_midi.mp3

or use lame

timidity my_midi_file.mid -Ow -o - | lame - -b 64 my_converted_midi.mp3

 

 

UBUNTU HOW TO REMOVE / REDUCE WHITE / BLANK MARGINS / SPACE ON PDF

In Ubuntu as an alternative to fineprint, page-crunch is suggested, but I don't find it useful, as multiple sheet printing is also available with the normal printing menu in ubuntu.

What is not available in page-crunche though is to put multiple sheets on one page and reduce the white space of each sheet.

Reduce the size of a Avi video

The easiest command I found, is using avconv. To install avconv in Ubuntu, open a terminal (Alt+Ctrl+t) and enter

sudo apt-get install libav-tools

To convert a video from .avi to .mp4, just use

avconv -i InputVideoName.avi outputVideoName.mp4

To change the size of the video you can add the -s flag, e.g.

avconv -i InputVideoName.avi -s 720x540 outputVideoName.mp4

 

Install Virtual Box on Host Lubuntu / Ubuntu. Problems with USB Port and Installation of Guest Addition on Guest Account of Virtualbox

To install virtualbox on the Host Ubuntu, better not use the version from the repository, i.e. do NOT

sudo apt-get install virtualbox 

but rather download and install it from the Oracle virtualbox website. Otherwise the USB port is not working, (see stackoverflow). I also encountered problems to install the Guest Addition, when installing virtualbox from the repository.

emacs Regular Expressions (regexp) Examples

||Symbols  Text a^2|| -> \norm{Symbols  Text a^2}

in Latex change I defined my own norm environment, using the \usepackage{amsmath} environment, by

\newcommand{\norm}[1]{\left\Vert#1\right\Vert}

Now I wanted to replace every pair || . || with \norm{.}, e.g.

||a^2 - b^2||^2

to

\norm{a^2 - b^2}^2
REGEXP

M-x query-replace-regexp

||\(.*?\)||

with

\\norm{\1}

The .* matches everything in a greedy way, that means a expression like

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