MKVToolnix recently released its 5.3.0 verison with following changes:

1. Several fields have been added to mkvmerge’s verbose identification output.
2. File type identification and a segfault have been fixed for DTS files.
3. File type detection for (E)AC3 files has been improved.
4. mkvextract’s “timecodes_v2″ mode uses the same track IDs as mkvmerge’s identification mode outputs again.
5. An invalid memory access with certain broken Matroska files has been fixed.
6. mkvmerge can read input files as if they were part of a single huge file.
7. mkvmerge can extract and use the audio encoder delay information stored in MP4 files as written by iTunes

To Install MKVToolNix in Ubuntu:

First to import public GPG key with this command:

wget -O - http://www.bunkus.org/gpg-pub-moritzbunkus.txt | sudo apt-key add -

Then edit the source by:

gksudo gedit /etc/apt/sources.list

11.10 oneiric add following lines (other releases replace oneiric):

deb http://www.bunkus.org/ubuntu/oneiric/ ./
deb-src http://www.bunkus.org/ubuntu/oneiric/ ./

Now update and install MKVToolNix by:

sudo apt-get update
sudo apt-get install mkvtoolnix mkvtoolnix-gui

Ubuntu – How to Install MKVToolNix (Matroska tools) in Linux is a post from: WhileIf Blog

We are not going to cover each one of these in this article, but I will show you a few use cases.

When including other scripts, it is a good idea to utilize the __FILE__ constant (or also __DIR__ , as of PHP 5.3):

// this is relative to the loaded script's path
// it may cause problems when running scripts from different directories
require_once('config/database.php');

// this is always relative to this file's path
// no matter where it was included from
require_once(dirname(__FILE__) . '/config/database.php');

Using __LINE__ makes debugging easier. You can track down the line numbers:

// some code
// ...
my_debug("some debug message", __LINE__);
/* prints
Line 4: some debug message
*/

// some more code
// ...
my_debug("another debug message", __LINE__);
/* prints
Line 11: another debug message
*/

function my_debug($msg, $line) {
echo "Line $line: $msg\n";
}

PHP – Magic Constants is a post from: WhileIf Blog

PHP has a garbage collector and a pretty complex memory manager.

The amount of memory being used by your script. can go up and down during the execution of a script. To get the current memory usage, we can use the memory_get_usage() function, and to get the highest amount of memory used at any point, we can use the memory_get_peak_usage() function.

echo "Initial: ".memory_get_usage()." bytes \n";
/* prints
Initial: 361400 bytes
*/

// let's use up some memory
for ($i = 0; $i < 100000; $i++) {
$array []= md5($i);
}

// let's remove half of the array
for ($i = 0; $i < 100000; $i++) {
unset($array[$i]);
}

echo "Final: ".memory_get_usage()." bytes \n";
/* prints
Final: 885912 bytes
*/

echo "Peak: ".memory_get_peak_usage()." bytes \n";
/* prints
Peak: 13687072 bytes
*/

PHP – Memory Usage Information is a post from: WhileIf Blog

// generate unique string
echo md5(time() . mt_rand(1,1000000));

There is actually a PHP function named uniqid() that is meant to be used for this.

// generate unique string
echo uniqid();
/* prints
4bd64c947233e
*/

// generate another unique string
echo uniqid();
/* prints
4bd67c9412340
*/

You may notice that even though the strings are unique, they seem similar for the first several characters. This is because the generated string is related to the server time. This actually has a nice side effect, as every new generated id comes later in alphabetical order, so they can be sorted.

To reduce the chances of getting a duplicate, you can pass a prefix, or the second parameter to increase entropy:

// with prefix
echo uniqid('foo_');
/* prints
foo_4bd67d6cd8b8f
*/

// with more entropy
echo uniqid('',true);
/* prints
4bd67d6cd8b926.12135106
*/

// both
echo uniqid('bar_',true);
/* prints
bar_4bd67da367b650.43684647
*/

This function will generate shorter strings than md5(), which will also save you some space.

PHP – Generating Unique ID’s is a post from: WhileIf Blog

First, here is an example with just optional arguments:

// function with 2 optional arguments
function foo($arg1 = '', $arg2 = '') {

echo "arg1: $arg1\n";
echo "arg2: $arg2\n";

}
foo('hello','world');
/* prints:
arg1: hello
arg2: world
*/

foo();
/* prints:
arg1:
arg2:
*/

Now, let’s see how we can build a function that accepts any number of arguments. This time we are going to utilize func_get_args():

// yes, the argument list can be empty
function foo() {

// returns an array of all passed arguments
$args = func_get_args();

foreach ($args as $k => $v) {
echo "arg".($k+1).": $v\n";
}

}

foo();
/* prints nothing */

foo('hello');
/* prints
arg1: hello
*/

foo('hello', 'world', 'again');
/* prints
arg1: hello
arg2: world
arg3: again
*/

PHP – Functions with Arbitrary Number of Arguments is a post from: WhileIf Blog

function genRandomString() {
$length = 10;
$characters = ’0123456789abcdefghijklmnopqrstuvwxyz’;
$string = ”;

for ($p = 0; $p < $length; $p++) {
$string .= $characters[mt_rand(0, strlen($characters))];
}

return $string;
}

PHP – Random string with numbers and letters is a post from: WhileIf Blog

var anchor = document.getElementById('someAnchor');
//anchor.id
// anchor.href
// anchor.title
// .etc

The only problem is that this doesn’t seem to work when you reference the DOM elements with jQuery, right? Well of course not.

// Fails
var id = $('#someAnchor').id;

So, should you need to access the href attribute (or any other native property or method for that matter), you have a handful of options.

// OPTION 1 - Use jQuery
var id = $('#someAnchor').attr('id');

// OPTION 2 - Access the DOM element
var id = $('#someAnchor')[0].id;

// OPTION 3 - Use jQuery's get method
var id = $('#someAnchor').get(0).id;

// OPTION 3b - Don't pass an index to get
anchorsArray = $('.someAnchors').get();
var thirdId = anchorsArray[2].id;

JQuery – Accessing Native Properties and Methods is a post from: WhileIf Blog

jQuery makes this ridiculously simple, by setting a header from within the $.ajax method.

 // Set header so the called script knows that it's an XMLHttpRequest
 // Only send the header if it's not a remote XHR
 if ( !remote ) {
 xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
 }
 

With this header set, we can now use PHP (or any other language) to check for this header, and proceed accordingly. For this, we check the value of $_SERVER['HTTP_X_REQUESTED_WITH'].

JQuery – Detect AJAX Requests with PHP is a post from: WhileIf Blog

Before

    $('')
      .attr({
        id : 'someId',
        className : 'someClass',
        href : 'somePath.html'
      });

After

    $('', {
        id : 'someId',
        className : 'someClass',
        href : 'somePath.html'
    });

Not only does this save a few characters, but it also makes for cleaner code. In addition to element attributes, we can even pass jQuery specific attributes and events, like click or text.

JQuery – Passing an Attribute Object is a post from: WhileIf Blog

Before

$('#someElement').hover(function() {
// mouseover
}, function() {
// mouseout
});

Now

 $('#someElement').hover(function() {
 // the toggle() method can be used here, if applicable
 });
 

Note that this isn’t an old vs. new deal. Many times, you’ll still need to pass two functions to hover, and that’s perfectly acceptable. However, if you only need to toggle some element (or something like that), passing a single anonymous function will save a handful of characters or so!

JQuery – A Single Hover Function is a post from: WhileIf Blog