Om4ar

ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

You can get the list of installed codecs with:

Download videos from egghead

Go to the egghead website, i.e. Building a React.js App

run

$.each($('h4 a'), function(index, video){
  console.log(video.href);
});

About

This is a git pre-push hook intended to help developers keep their PHP code base clean by performing a scan with PHP CodeSniffer whenever new code is pushed to the repository. When any coding standards violations are present the push is rejected, allowing the developer to fix the code before making it public.

To increase performance only the changed files are checked when new code is

#Use pprof debug docker daemon

Use pprof debug docker daemon
pprof debug entrypoint
Start docker daemon in debug mode
Run socat to make docker sock available via tcp port
Access debug url entrypoint

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

Concurrency in JavaScript

Javascript is a programming language with a peculiar twist. Its event driven model means that nothing blocks and everything runs concurrently. This is not to be confused with the same type of concurrency as running in parallel on multiple cores. Javascript is single threaded so each program runs on a single core yet every line of code executes without waiting for anything to return. This sounds weird but it's true. If you want to have any type of sequential ordering you can use events, callbacks, or as of late promises.

Here's how you could create custom error classes in Node.js using latest ES6 / ES2015 syntax.

I've tried to make it as lean and unobtrusive as possible.

Defining our own base class for errors

errors/AppError.js

	// https://codepen.io/hartzis/pen/VvNGZP
	class ImageUpload extends Component {
	constructor(props) {
	super(props);
	this.state = {
	file: '',
	imagePreviewUrl: ''
	};
	this._handleImageChange = this._handleImageChange.bind(this);
	this._handleSubmit = this._handleSubmit.bind(this);

	'use strict';

	// The purpose of this example is to show
	// how you can block the event loop with JavaScript.
	// There is 3 routes
	// / respond with Hello, World text
	// /block uses JavaScript while for 5 seconds
	// /non-block uses setTimeout for 5 seconds

	// Do the following

	<?php // /app/Http/Middleware/Cors.php

	namespace App\Http\Middleware;

	use Closure;

	class Cors {
	public function handle($request, Closure $next)
	{
	return $next($request)