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  Capture video stream with WebRTC

WebRTC(Web Real-Time Communication) is an API supporting real time audio and video communication through a browser. It is now a recommended W3C standard. This post is to show you how to capture video stream and screenshot with WebRTC. Capture video stream To play video stream from the video camera, we first need to put a video tag in our code: <video id="video"></video> The main function to get the video stream is the navigator.getUserMedia, as of now only few of the browsers support...

   WebRTC,Video,Screenshot     2013-10-24 21:04:41

  noConflict mechanism in jQuery

Many JavaScript frameworks like to use $ as function or variable name, jQuery is one of them. In jQuery, $ is just a reference to window.jQuery, so even if $ is deleted, window.jQuery will still be available to ensure the whole library can work normally. jQuery API design takes fully consideration of multiple frameworks conflicts, we can use jQuery.noConflict function to easily handle control. jQuery.noConflict accepts one optional boolean parameter[1] to determine whether to hand jQuery object ...

   jQuery,noConflict,$     2013-03-14 19:40:36

  A mini guide to HTTP referer

In HTTP header, there is a field named Referer which is to provide the referrer of the current accessed page. In this post, we will introduce the usage of HTTP referer field. On the web, when a user visits a webpage, s/he must be from some place. This place is usually referred a s referer. This information is very important to some website operators and server owners as they want to know where they get the traffic from and this helps them provide better service for potential targeted users. In t...

   HTML,HTTP REFERER,REFERRERPOLICY     2019-06-29 02:23:25

  A trap about PHP random number

The method to get random number in PHP is very simple, we only need to use rand() function. int rand ( int $min , int $max ) One function call can return the random number in a specified range. But in fact, the random number in computer is actually pseudorandomness, generally to increase the randomness, we may set a random seed before calling rand(). void srand ([ int $seed ] ) According to other language features, we should pass a time value as a parameter to the srand() function, generally...

   PHP,rand,srand,mt_rand     2013-06-07 09:10:10

  PHP advisory file lock : flock

When we process a file in PHP, we may often need to acquire a lock so that other scripts cannot edit the same file at the same time. There is a flock() function in PHP which can help us lock the file we want to process. But there is one issue we should take care. Recently, ffb encountered one issue while he was trying to lock a file handle. The codes are below: $filename = "/tmp/lock.txt";      $fp = fopen($filename, "r+");   if (!$fp...

   flock(),advisory locking,PHP     2013-04-23 11:42:48

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  A C++ program puzzle

Recently I came across a question asked by wang2191195 on a Chinese IT forum CSDN which asks about a C++ program puzzle. He has a code snippet which cannot be compiled. The code is:#include <cstdlib> #include <iostream> using namespace std; class Base{ public: virtual void func(){ cout << "Base::func()" << endl; } virtual int func( int num ){ cout << "Base::func( int " << num << " )" << endl; return 0; ...

   C++,Puzzle,Hide,Overload     2012-05-13 02:31:26

  Using OpenID connect in asp.net for login via Facebook

This post is shared by asp.net development India experts to explain OpenID support and OAuth providers support in asp.net. Through this article, you will learn the best way to use OpenId in asp.net development for login through different accounts including Facebook. Read this article and discover how experts of asp.net do it. Web pages of Asp.Net have support for OpenID and OAuth providers. These providers allow users to log in to the web application with their credentials from Microsoft, Google...

   ASP.NET ,DEVELOPMENT,INDIA     2016-11-07 05:09:58

  Highly efficient PHP code writing

Next are some tips for writing highly efficient PHP codes. They are described below: 0. Use single quote to replace double quote, this will be better since PHP will serach for variables in double quoted strings. Note, only echo can do this; 1. If we can define methods of a class as static, then do it. It will increase access speed by 4 times; 2. $row["id"] is 7 times faster than $row[id]; 3. echo is faster than print, and also use echo's multiple parameter format such as echo $str1,$str2 inst...

   PHP,Code writing,High efficient,Tips     2011-07-23 12:35:50

  Java AbstractMethodError explained and demonstrated

According to Oracle Java API documentation, AbstractMethodError is a kind of runtime error where the application is having some incompatible changes which leads to a missing implementation of an abstract method. Below is the official description. Thrown when an application tries to call an abstract method. Normally, this error is caught by the compiler; this error can only occur at run time if the definition of some class has incompatibly changed since the currently executing method was last co...

   JAVA,ABSTRACTMETHODERROR     2016-07-22 22:03:20

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