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Friday, July 6, 2012

Testing your disks using dd utility and time.

You can execute copies a large block of data to and from disk.

This will minimize disk caching.

Next is one example if our test system has 1GB of RAM.

It is easy ( 1GB = 250,000 blocks ).

$ time sh -c "dd if=/dev/zero of=bigfile bs=8k count=250000 && sync"
250000+0 records in
250000+0 records out
2048000000 bytes (2.0 GB) copied, 37.0113 s, 55.3 MB/s

real 0m40.910s
user 0m0.172s
sys 0m12.641s

It's very hard to argue with this dd test.

Thursday, July 5, 2012

Using DIGITAL PEN CAMERA eheV1-USB-II with mplayer

It's not my camera, I take it just to try to make working on Linux OS.
This is the device.

The dmesg tell me about this camera:
uvcvideo: Found UVC 1.00 device USB2.0 Camera
If you want to see and not to take frames, then use :
mplayer tv:// driver=v4l2:width=640:height=480:device=/dev/video0 -vo null
You can try to take some frames. I use this:
mplayer tv:// -frames 10 -tv fps=20:driver=v4l2:width=640:height=480:device=/dev/video0 -vo jpeg
The result is ten frames.
On this image I draw one line to see how working default.

And using the zoom ...

Friday, June 15, 2012

Working with old video card and also old Ogre 3D engine and Blender 3D.

I make today a new tutorial about the trips and tricks with Ogre 3D engine using Blender 3D.
If you want to see this, you can go on the tutorials part from my site.
This is the just a result of my simple example.
The result is shown in next image sample.

Thursday, June 14, 2012

News: Programming with google-blocky

It's fun. You can try or your children.
Blockly is a web-based, graphical programming language. Users can drag blocks together to build an application. No typing required.

You can see more on google project.

Saturday, May 26, 2012

Show large image like thumbnails in firefox using greasemonkey

Today I focused on a problem you often encounter.

We have a web folder containing a series of large image files. We want to see the folder that contains but would be difficult to download all the images and then view them search to find a picture of us.

I installed Greasemonkey addon and I began to study how it works.

I don't have experience with javascript programming.

I still managed to make the script below:

// ==UserScript==
// @name        show-image
// @namespace   show-image
// @description show images from files
// @include     http://*
// @version     0.1
// ==/UserScript==
var elements = document.getElementsByTagName("a");
  for (var i=0; (anchor=elements[i]); i++) {
   src = anchor.getAttribute("href");
  if (src.indexOf('.gif') > -1 || src.indexOf('.jpg') > -1 || src.indexOf('.JPG') > -1 || src.indexOf('.jpeg') > -1)
  {
    img = document.createElement('img');
    img.setAttribute('src',src);
    img.style.width='10%';
    anchor.appendChild(img);
   }
  }

You can add to show the png file by adding in the if condition in the script :

src.indexOf('.png') > -1 || src.indexOf('.PNG') > -1

I hope to help you.

Monday, May 21, 2012

News: Working with python , opengl and ARB ...

Today I test a simple script that uses the OpenGL ARB "Architecture Review Board".
The script is very simple and can be found on my graphic-3d.blogspot.com.
I make this with Python 2.6.4 , pyopengl module.

Sunday, April 1, 2012

Fedora online defragmenter for ext4 filesystem

The tool is e4defrag.
The man page tells us: reduces fragmentation of extent based file.
The file targeted by e4defrag is created on ext4 filesystem made with "-O extent" option (see mke2fs(8)). The targeted file gets more contiguous blocks and improves the file access speed.
Let's try this tool.
You can try under root account this:
# e4defrag -test -cv /home/your_user/
The final result on my account is :
Total/best extents 170276/165520 Fragmentation ratio 0.03% Fragmentation score 0.24 [0-30 no problem: 31-55 a little bit fragmented: 55- needs defrag]
Also, you have to run e4defrag with the -test parameter for now, since it isn't a fully tested version.