Posts

Showing posts from 2014

Current working directory of a process

Recently, I am dealing with a lot of automation scripts and running automation jobs. Sometimes, it is required for me to kill my jobs to give way to other processes. :(

Anyway, I need to continue my automation job after the "higher priority" processes completed. Thus, the working directory of my process is EXTREMEly important.

So, before killing the job, I have already gotten the pid. To get the working directory, use pwdx command with the pid will do.

pwdx <pid>
Example:

pwdx 1234
For further information or more ways to do this, check out this page: http://www.cyberciti.biz/tips/linux-report-current-working-directory-of-process.html


Usage of the 5 most important synthesis modules

Image
Hello there. I am Jonie Lim from Malaysia. This is the final assignment from Introduction to Music Production on Coursera. For this week, I am choosing the topic of explain the usage of the 5 most important synthesis modules.

Let me further break these 5 modules into 2 categories, the primary modulation and the secondary modulation. The oscillator, filter and amplifier are of primary modulation. They work directly on the sound that we will hear. The secondary modulation includes the LFO and envelope, which will modulate the primary modulation during the audio signal manipulations.

Primary modulation
Oscillator is also known as VCO, voltage controlled oscillator. The main functino of this module is to create the sound. It creates the sound with a timbre based on the waveform selected in the synthesizer. Sine wave is normally giving a single frequency range, triangle and square waveform will have the fundamental plus the odd harmonics, while sawtooth waveform will gives fundamental plus …

Flanger vs Phaser

Image
Hello there! I am Jonie Lim from Malaysia. This is the 5th week assignment for Introduction to Music Production on Coursera. This week topic is very tough for me, I'll try my best to explain how short delay effects, i.e. flanger and phaser function.

Firstly, as usual, let's listen to the original guitar sound which I have pre-recorded. Warning: I am not a good guitar player. :P



My workspace.


In order try to show the difference between the flanger and the phaser, I have the parameters set similarly.



Note that I have both set to the highest intensity to make sure the effect is significantly audible. Next, I set both speed to 0.5Hz. This is the low frequency used to modulate the signals. The flanger can have the feedback set to be inverted or normally here. Since the phaser cannot have it set inverted, thus I have both of them set to 50%, and the feedback of flanger is set towards normal feedback.

Next, let's look at some technical aspects of the 2 audio effects.

A flanger i…

Noise Gate

Image
Hi! I am Jonie Lim from Malaysia. In this week 4 assignment, I would like to dive in the noise gate plugin. I have a very simple "studio" setup, a MacBook, itself. I don't have a mic or special room to do recording, thus accoustic noise is my #1 concern in recording. In this blog post, I'll be using one of my previous recordings to demonstrate how to use the noise gate. I am using GarageBand 5 for this assignment.




This is the audio waveform from the small purple recording that is splited and copied out from the original recording. To hear the contrast, the effects or plugin that I have put on that track are removed.

This is the original recording sounds like. You hear a "click" sound at 0:04 going into 0:05, and also notice the significant noise right after the singing phrase.







Look at the audio waveform, the "click" sound is highlighted. To get rid of the noise and also the unintentional "click" sound, we can use a noise gate plugin to f…

Audio effects

Image
Hi! I am Jonie Lim from Malaysia. In this blog post, I would like to talk about the audio effects. This would be my 3rd week assignment for Introduction to Music Production.

Basically, there are 3 major categories of audio effects, which related to the 3 properties of sound. I am going to take a plugin for each category, and explain how these plugins work in GarageBand 5.

I have recorded a singing on 4 notes and export to mp3 with no audio effect being applied.


You can listen it here.



1. Dynamic Effects Dynamic effects play with the amplitude of the sound. One of the plugins that put manipulate amplitute of the sound is compressors. Basically, a compressor would "squeeze" an audio signal when it rises above a specific threshold level. In GarageBand, it would then take the setting of ratio for the strength of the compression, attack setting for when the compressor should react to the signal breaching the threshold, and then the gain setting to set the loudness of the effect t…

Add a software instrument and record MIDI using GarageBand

Image
Hi! I am Jonie Lim from Malaysia. This is my second week assignment for Introduction to Music Production on Coursera. I am choosing the topic to record a MIDI in DAW (Digital Audio Workstation). I am using GarageBand as my DAW. I am using GarageBand 5. Yes, it is a very old version, my Macbook is currently 5 years old. :P

Firstly, I am creating a test project in GarageBand. I set the Count In as the click and countoff (this is what I understand what it is). I also turned on the Metronome so I could follow the tempo of the project that I have set, which is 120.




Then, I created a new track selecting Software Instrument.


I have my MIDI controller connected to my Macbook. Got this MIDI controller last year when I have a chance to go to US. Haven't work out anything from it, yet. Thanks to this course, it help me to find ways to play with this! :D


I can select which software instrument to be used from the right menu on the right of GarageBand.


I selected the Planetarium from Synth Bas…

Type and Usage of Important Studio Cables

Image
Hi, I am Jonie Lim from Malaysia. This is an assignment from a course that I am currently taking in Coursera, Introduction to Music Production. I will be sharing about the type and usage of some of the studio cables that normally used. I wanted to do this in video format, but I guess I would do this better as a blog post.

In a more specific terminology, the word "cable" actually refer to the cord or wire that is used to connect an input device and an output device. However, what we are discussing here about the studio cables that are more focusing to the connectors that act like an interface between the cord/wire with the input/output devices.

There are 2 categories of type discussed here. One is balanced cable or unbalanced cable, the other category is analog or digital cable.



XLR cable


XLR cable normally used for professional audio applications, such as microphones. The end points of this cable has a male and female XLR connectors, which has three pins or three holes respec…

Disable ssh timeout on client site

I think this is the nth time I Google for it, and look for the right result that solve this problem. Never have the solution stick in my mind. Keeping this for my own reference. :)

Update /etc/ssh/ssh_config with this line :

ServerAliveInterval 300
Reference : How to disable SSH timeout

The reference said it works for Ubuntu (I personally tested) / Debian. I am setting this in CentOS, it works too. :)




CGI - Common Gateway Interface

What is the first thing come to your mind, when you see... CGI? Me -- Perl. But it's actually more than Perl. Here's some examples on CGI in different languages and some setups on Ubuntu to get the web server running.

To setup Apache2 in Ubuntu. This will install and run the Apache2 server :

sudo apt-get install apache2
By default, the cgi directory is setup at /usr/lib/cgi-bin. Just have your cgi scripts or executable put in this directory (make sure it's executable) and it can be access via http://localhost/cgi-bin/path. This can be modified at the config file. The default config file is at /etc/apache2/sites-available/default. The section of the file that related to this looked like this :

ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory>
The access and error log can be found at /var/log/apache2/.

OK…

RCS - Revision Control System

Image
I almost forgot about RCS! Keeping this for my future reference.

This revision control system required minimum setup. What I need is just simply to have RCS installed.

To install in Ubuntu :

sudo apt-get install rcs
To check-in your file :

ci filename
You will see a new file created in the same directory :

filename,v
And you'll wondering where your file is.

To keep your file "visible", add the -u switch.

ci -u filename
To make it more organized, create a RCS directory in your working directory, so the ,v file will be stored in RCS directory.

If you are using the ci without -u switch, you can use co command to checkout the file.

co filename
To check out and lock the file for edit, use the -l switch :

co -l filename
To do a diff with your changes and the last check-in version :

rcsdiff filename
To see the log and change summary of each check-in :

rlog filename
Some screenshots for the above mentioned commands.