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@amishshah
amishshah / ogg-containers.md
Last active Jan 20, 2020
A guide to the Ogg container format for demuxing opus audio
View ogg-containers.md

You take a stream/buffer of binary data. The start of your data is a "Page", which has a header followed by data.

Header

You need to read the following data from the header (see https://xiph.org/ogg/doc/framing.html for more detail)

  • capture_pattern - bytes 0 to 3, must read OggS
  • stream_structure_version - byte 4, must be 0
  • header_type_flag - byte 5, a bitflag that tells you metadata about the page (is it a new packet? is a packet continued here? is it the first/last page of the stream?)
  • absolute granule position - bytes 6 to 13, not needed unless you want seeking
  • stream serial number - bytes 14 to 17, a serial number given to each stream contained in the Ogg file. This is important for playing Ogg files that contain other streams, such as video or cover art. You need to identify and only bother parsing the Opus stream.
@spvkgn
spvkgn / opus-tools_static_build.sh
Last active Apr 7, 2020
Script to build a statically linked opus-tools
View opus-tools_static_build.sh
#!/bin/sh
# ==============================================================
# Script to build a statically linked version of opus-tools
#
# Release tarballs:
# http://downloads.xiph.org/releases/opus/
# http://downloads.xiph.org/releases/ogg/
# http://downloads.xiph.org/releases/flac/
#
@Jozo132
Jozo132 / float32encoding.js
Last active Jun 3, 2020
JavaScript (Node.js) IEEE 754 Single precision Floating-Point (32-bit) binary conversion from and to both Hex and Bin
View float32encoding.js
// Forked 'toFloat' from https://gist.github.com/laerciobernardo/498f7ba1c269208799498ea8805d8c30
// Forked 'toHex' from stackoverflow answer https://stackoverflow.com/a/47187116/10522253
// Modifyed by: Jozo132 (https://github.com/Jozo132)
const Float32ToHex = (float32) => {
const getHex = i => ('00' + i.toString(16)).slice(-2);
var view = new DataView(new ArrayBuffer(4))
view.setFloat32(0, float32);
return Array.apply(null, { length: 4 }).map((_, i) => getHex(view.getUint8(i))).join('');
}
@wernight
wernight / inotifyexec.py
Last active Jul 27, 2020
inotifywait helper that executes a command on file change (for Linux, put it in ~/bin/)
View inotifyexec.py
#!/usr/bin/env python
"""Use inotify to watch a directory and execute a command on file change.
Watch for any file change below current directory (using inotify via pyinotify)
and execute the given command on file change.
Just using inotify-tools `while inotifywait -r -e close_write .; do something; done`
has many issues which are fixed by this tools:
* If your editor creates a backup before writing the file, it'll trigger multiple times.
* If your directory structure is deep, it'll have to reinitialize inotify after each change.
@laerciobernardo
laerciobernardo / hexIEEEtoFloat.js
Last active Aug 10, 2020
Convert Hexadecimal IEEE754 to Float in Javascript
View hexIEEEtoFloat.js
var str = '0x41FC6733';
function parseFloat(str) {
var float = 0, sign, order, mantiss,exp,
int = 0, multi = 1;
if (/^0x/.exec(str)) {
int = parseInt(str,16);
}else{
for (var i = str.length -1; i >=0; i -= 1) {
if (str.charCodeAt(i)>255) {
@domenic
domenic / 1-service-worker.js
Last active Aug 12, 2020
Service worker stream transferring
View 1-service-worker.js
"use strict";
const worker = new Worker("worker.js");
self.onfetch = e => {
const transform = new TransformStream(); // creates an identity transform
e.respondWith(new Response(transform.readable));
// Give the worker the writable end. An identity transform stream will just shuffle
// bytes written there into transform.readable.
@mathisonian
mathisonian / index.md
Last active Sep 1, 2020
requiring npm modules in the browser console
View index.md

demo gif

The final result: require() any module on npm in your browser console with browserify

This article is written to explain how the above gif works in the chrome (and other) browser consoles. A quick disclaimer: this whole thing is a huge hack, it shouldn't be used for anything seriously, and there are probably much better ways of accomplishing the same.

Update: There are much better ways of accomplishing the same, and the script has been updated to use a much simpler method pulling directly from browserify-cdn. See this thread for details: https://github.com/mathisonian/requirify/issues/5

inspiration

@bayotop
bayotop / last-evet-id.md
Last active Sep 6, 2020
Sending arbitrary Last-Event-ID header values across origins using the EventSource API.
View last-evet-id.md

The EventSource API

The EventSource interface is used to receive server-sent events. It connects to a server over HTTP and receives events in text/event-stream format without closing the connection.

https://developer.mozilla.org/en-US/docs/Web/API/EventSource

Last-Event-ID

Setting an ID lets the browser keep track of the last event fired so that if, the connection to the server is dropped, a special HTTP header (Last-Event-ID) is set with the new request.

@littledan
littledan / anonymous-inline-modules.md
Last active Sep 8, 2020
Anonymous inline modules
View anonymous-inline-modules.md

Anonymous inline modules

Anonymous inline modules are syntax for the contents of a module, which can then be imported.

let inlineModule = module {
  export let y = 1;
};
let moduleExports = await import(inlineModule);
assert(moduleExports.y === 1);
@Vestride
Vestride / encoding-video.md
Last active Sep 18, 2020
Encoding video for the web
View encoding-video.md

Encoding Video

Installing

Install FFmpeg with homebrew. You'll need to install it with a couple flags for webm and the AAC audio codec.

brew install ffmpeg --with-libvpx --with-libvorbis --with-fdk-aac --with-opus
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