How to remove noise from audio using Audacity

Audacity is an open source audio editor, very powerful and free, available in Mac and other major platforms. I use it to record my short audio program.

No matter what microphone you use, no matter how quiet your room is, your audio always includes some background noise.

Screenshot 2015-03-31 09.22.04

Like this audio above, the selection should be blank, but you can see some wave, because my microphone, and my fan etc. Audiences will hear it loud and clear, and nobody will like it.

But we can use Noise Removal Effect built in Audacity to fix it.

First step, select some background noise like the picture above. Then click menu Effect -> Noise Removal, this dialog box will appear.

Screenshot 2015-03-31 09.29.59

Click the Get Noise Profile button, the dialog box will disappear.

Then select the whole audio or what segment you need, and click menu Effect -> Noise Removal again, then click Ok button, and then everything is done.

Screenshot 2015-03-31 09.35.26

Now you can see the same section as the first picture, but these is a very clear line now.

Is Chinese anti-corruption action actually an internal struggle among political leaders?

We cannot know exactly what is Xi Jinping’s thinking. I think:

  • Xi Jinping need to protect himself. From public information and some
    unofficial information. We now know there was a plan to replace Xi
    Jinping with Bo Xilai. Game of throne Chinese version, and the better
    version. So Xi Jinping need to wipe out the conspiracy and everyone
    behind this conspiracy.
  • Xi Jinping acts very like Mao Zedong. Mao likes absolute authority.
    Anti-corruption is a very effective way to obtain absolute authority.
    Zhou Yongkang, Xu Caihou and all the big tigers were a sort of club
    members of Jiang Zemin.
  • We like Anti-corruption, corruption already caused a lot of problems.
    But now, I am not persuaded the anti-corruption campaign will last
    forever. When all enemies in the party are wiped out, Will Xi Jinping
    carry on fighting corruption?

Actually, I think the most important thing is what’s next. After Xi Jinping get his absolute authority, what is he wants? What direction he wants China to go?

Which are some of the character traits that most developers have in common?

  • We really like computer. Computer is a stupid machine, computer cannot independently do anything, you must tell it what to do, and how to do it. But the computer is a loyalty friend, he never lies, never cheat, never be angry with you. You can always rely on him. He is never lazy.
  • We like self-study. If you want to get jobs done, you must learn a lot of things yourself. Every year new languages, new technologies, new tools, new libraries appear, if you don’t want to be dropped behind, you must learn a lot.
  • We enjoy challenges. Everything that kills me makes me feel alive.
  • We love efficiency.
  • We like good structure.
  • We hate bureaucracy.

What is the best profession in the world?

A programmer of course.

Low entry barriers: I know a lot of people learn how to program from other professions. When I lay in college, my major was mechanical engineering. Some talented programmers from Vietnamese major, from constructional engineering major, English major and so on. I learn how to program from 1992, when I was 13 years old. And I met some 13~17 years old very cool programmer, they are very clever kids and know a lot of stuff.

Low material needs: Computer was very expensive before. But now even in China, almost every citizen gets one or more computer in the house. You do not have the required any land, money, any materials, only use your mind, the computer and the internet connection, you can make money wherever you are.

Long career: If you want, you can keep your career as long as possible.

A lot of needs: The world is rapidly changing. Everything will be connected to the internet. There are a lot of needs of programmers.

How expensive is rent in Shanghai?

It depends on where you live and the type of the apartment. One bedroom apartment is called “一室” in Shanghai, and two bedrooms apartment is called “两室”, and so on. Normally one bedroom is more expensive counts by area. In my area, a very old one bedroom apartment costs 3000 RMB/month, but a new cozy two bedrooms apartment only costs 4800RMB/month. If you need more rational choices, you may want share apartment with others.

You can use “安居客” or “爱屋吉屋” look the price by the map (in Chinese).
Url of “安居客”: 上海地图租房

Url of “爱屋吉屋”:

And there is a website of “老外” (in English): Housing

What is Dato ( GraphLab )?

Dato is the new name of GraphLab, January 8, 2015, they announced it closed an $18.5 million Series B funding round, and change name from GraphLab to Dato.

They change name because:

“The new name [Dato] is meant to show that the company’s software can handle all sorts of machine learning tasks—not just graph analysis.”

Source: Dato Joins New Wave of Machine Learning Startups | WIRED

What is Dato ( GraphLab )

At first GraphLab mainly was designed to operate on a graph data structure much similar to Google’s system Pregel. But now GraphLab can handle other datas and problems.

How to install GraphLab Create on Mac OS X

GraphLab Create need Mac OS X 10.8+, and Python 2.7.x, and pip, and because demos in their document need iPython and iPython notebook, you may want install these first.

install iPython:

install iPython notebook:

install GraphLab Create:

And when I use some demos, I found these kind error informations:

You can fix it by, add blow to end of ~/.bash_profile file:

and reload ~/.bash_profile file:

Reading material of Deep learning

From this question of Quora:




Online courses:



Some collections: