Sal Rahman shovon

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

Live streaming with HTML5

This document contains collected notes regarding html5 live streaming approaches. I'm trying to understand how to build a system that enables streaming of live video to HTML5 clients. Following content is mainly centered around MPEG-DASH - modern way of dealing with given needs.

Approach 1

To prepare movie.avi from MPEG-DASH streaming we will execute following ffmpeg commands:

> ffmpeg -y -i movie.avi -an -c:v libx264 -x264opts 'keyint=24:min-keyint=24:no-scenecut' -b:v 1500k -maxrate 1500k -bufsize 3000k -vf "scale=-1:720" movie-720.mp4
> ffmpeg -y -i movie.avi -an -c:v libx264 -x264opts 'keyint=24:min-keyint=24:no-scenecut' -b:v 800k -maxrate 800k -bufsize 1600k -vf "scale=-1:540" movie-540.mp4
&gt; ffmpeg -y -i movie.avi -an -c:v libx264 -x264opts 'keyint=24:min-keyint=24:no-scenecut' -b:v 400k -maxrate 400k -bufsize 800k -vf "scale=-1:360" movie-360.mp4

QEMU arm64 cloud server emulation

This is basically a rehash of an original post on CNXSoft - all credit (particularly for the Virtio device arguments used below) belongs to the author of that piece.

Download the latest uefi1.img image. E.g. ubuntu-16.04-server-cloudimg-arm64-uefi1.img from https://cloud-images.ubuntu.com/releases/16.04/release/

Download the UEFI firmware image QEMU_EFI.fd from https://releases.linaro.org/components/kernel/uefi-linaro/latest/release/qemu64/

Determine your current username and get your current ssh public key:

Why imperative imports are slower than declarative imports

A lot of people misunderstood Top-level await is a footgun, including me. I thought the primary danger was that people would be able to put things like AJAX requests in their top-level await expressions, and that this was terrible because await strongly encourages sequential operations even though a lot of the asynchronous activity we're talking about should actually happen concurrently.

But that's not the worst of it. Imperative module loading is intrinsically bad for app startup performance, in ways that are quite subtle.

Consider an app like this:

// main.js

Edit — February 2019

This gist had a far larger impact than I imagined it would, and apparently people are still finding it, so a quick update:

TC39 is currently moving forward with a slightly different version of TLA, referred to as 'variant B', in which a module with TLA doesn't block sibling execution. This vastly reduces the danger of parallelizable work happening in serial and thereby delaying startup, which was the concern that motivated me to write this gist
In the wild, we're seeing (async main(){...}()) as a substitute for TLA. This completely eliminates the blocking problem (yay!) but it's less powerful, and harder to statically analyse (boo). In other words the lack of TLA is causing real problems
Therefore, a version of TLA that solves the original issue is a valuable addition to the language, and I'm in full support of the current proposal, which you can read here.

I'll leave the rest of this document unedited, for archaeological

	<?
	# MIT license, do whatever you want with it
	#
	# This is my invoice.php page which I use to make invoices that customers want,
	# with their address on it and which are easily printable. I love Stripe but
	# their invoices and receipts were too wild for my customers on Remote OK
	#

	require_once(__DIR__.'/../vendor/autoload.php');

	/*
	MIT License

	Copyright (c) 2020 Egor Nepomnyaschih

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is

	// memoizes ordinary functions
	const memoized = (fn, keymaker = JSON.stringify) => {
	const lookupTable = new Map();

	return function (...args) {
	const key = keymaker.call(this, args);

	return lookupTable[key] \|\| (lookupTable[key] = fn.apply(this, args));
	}
	};

	export class WeakCache<T extends object, U> {
	private readonly cacheItems: WeakDictionary<T, U>;

	constructor() {
	if (typeof WeakMap !== "undefined")
	this.cacheItems = new WeakMap<T, U>();
	else
	this.cacheItems = new Es5WeakMap();
	}

	variable "aws_region" {
	default = "eu-west-1"
	}

	variable "domain" {
	default = "my_domain"
	}

	provider "aws" {
	region = "${var.aws_region}"